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A study on the use of ICP-OES for the determination of nonmetals in organic solution Hauser, Peter Christian 1984

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A STUDY ON THE USE OF ICP-OES FOR THE DETERMINATION OF NONMETALS IN ORGANIC SOLUTION by PETER C H R I S T I A N  HAUSER  Chem. H T L . W i n t e r t h u r P o l y t e c h n i c  1980  A THESIS SUBMITTED I N P A R T I A L F U L F I L L M E N T THE R E Q U I R E M E N T S FOR THE DEGREE OF MASTER  OF  SCIENCE  in THE F A C U L T Y OF GRADUATE (Department  We  accept to  this  STUDIES  of Chemistry)  thesis  as  conforming  t h e rejj,u3_T"e^-_atandard  THE U N I V E R S I T Y OF B R I T I S H COLUMBIA November ®  Peter Christian  1984 Hauser,  1984  _c -  OF  In p r e s e n t i n g  t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of  requirements f o r an advanced degree at the  the  University  o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make it  f r e e l y a v a i l a b l e f o r reference  and  study.  I  further  agree t h a t p e r m i s s i o n f o r e x t e n s i v e copying of t h i s t h e s i s f o r s c h o l a r l y purposes may  be granted by the head o f  department or by h i s or her  representatives.  my  It is  understood t h a t copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain  s h a l l not be allowed without my  permission.  Department of The  U n i v e r s i t y of B r i t i s h  1956  Main M a l l  Vancouver, Canada V6T 1Y3  E-6  (3/81)  Columbia  written  ABSTRACT  The  a p p l i c a t i o n of  Emission total  Spectrometry  oxygen,  been  studied.  nonmetals been by  have  and  Near-infrared been  used  respect  with  to  an  the  interference  was  Spatially  resolved  have  c o l l e c t e d as  been The  the  nonmetal b o i l i n g  nonmetal chamber  because was  aerosol  series  of  The working  the  aerosol  atomic part  of  an  stream  to  the  of  the  curves  and  by  of  solution of  the  has  three  in  xylene  have  the  first  time  of  atomization  these  with  potential  environment.  emission  profiles  investigations. were  compounds effect  plasma.  plasma  studied and  excitation  enrichment  been  coupled  been  molecular  the  to  utility  for  have  redistribution  have  limits  intensities  leading  compounds  of  and  emission  a  lines  inductively  complex  point  Optical  determination  in organic  determined  completeness the  Plasma  sample.  organic  from  the  detection  c h a r a c t e r i s t i c s of  used  to  emission  and  Oxygen  Coupled  sulphur  ICP-OES i n a nongaseous  when  the  (ICP-OES)  nitrogen  established.  The  on  Inductively  of  found  to  depend  containing in  the  volatile  Response  the  nebulizer solutes  factors  in  for  a  determined.  method testing  was  shown  certified  by  establishing standards  for  sulphur.  OR. MICHAEL BLADES  CHEMISTRY DEPT. UNIV. OF BRITISH COLUMBIA  i i  T A B L E OF  CONTENTS  PAGE  ABSTRACT TABLE  i i  OF CONTENTS  LIST  OF  TABLES  LIST  OF  FIGURES  i i i vi v i i  CHAPTER  I  INTRODUCTION 1.1  OBJECTIVE  1.2  THE  1.3  APPLICATIONS  1.4  FUNDAMENTALS  1 1  INDUCTIVELY  1.4.1  AEROSOL  1.4.2  TORCH  COUPLED  PLASMA  TO  ORGANIC  SAMPLES  OF  ORGANIC  SAMPLE  PRODUCTION  3 AND  NONMETALS  INTRODUCTION  8 11 12 15  1.4.3 PLASMA  16  1.4.4  SPECTRUM  20  1.4.5  SUMMARY  21  i i i  II  EXPERIMENTAL  23  2.1  INSTRUMENTATION  23  2.2  TORCH  27  2.3 A C Q U I S I T I O N  III  RESULTS  AND  OF  EMISSION PROFILES  DISCUSSION  3.1  NEAR-IR  3.2  P H Y S I C A L APPEARANCE  3.3  COMPLETENESS 3.3.1 3.3.2  OXYGEN,  AND  OF T H E  SULPHUR  LINES  31  *XYLENE-PLASMA*  37  ATOMIZATION  E M I S S I O N FROM EMISSION C  2  39  DIATOMIC MOLECULES  41  PROFILES  44  AND  47  CN C I AND  3.4  31  NITROGEN  OF  3.3.3  29  SI  53  CONCLUSIONS  58  OPTIMIZATION  59  3.4.1  ENTRAINMENT  OF  3.4.2  E X C L U S I O N OF A I R  3.4.3  AMBIENT  3.4.4  OPERATING  3.4.5  CONTROLLEED  3.4.6  CONCLUSIONS  OXYGEN  AIR  AND  59 59 NITROGEN  CONDITIONS SAMPLE  AND  VIEWING  DELIVERY  64 REGION  66 71 71  iv  3.5  IV  A N A L Y T I C A L PERFORMANCE  74  3.5.1  74  RESPONSE  FROM  D I F F E R E N T COMPOUNDS  V O L A T I L E SOLUTES  74  NONVOLATILE  SOLUTES  79  3.5.2  AMOUNTS  OF  OXYGEN  3.5.3  SIGNAL  3.5.4  DRIFTS  3.5.5  DETECTION  3.5.6  WORKING  3.5.7  CERTIFIED  CONCLUSION  BIBLIOGRAPHY  TO  AMBIENT  AND  NITROGEN  BACKGROUND RATIOS  82 82 82  LIMITS  84  CURVES O I L STANDARDS  87 FOR  SULPHUR  91  96  99  v  LIST OF TABLES  PAGE I  Organic  II  D i s s o c i a t i o n and  III  Sample  Volatile  V  Nonvolatile  VI  Detection  VII  NBS  VIII  NBS:  Dilutions  IX  NBS:  Standard  Solutes  P r o f i l e s  40 46 75  Solutes  80  Limits  86  Samples  NBS:  11  Ionization Energies  E x pe r i m e n t a 1 C o n d i t i o n s f o r  IV  X  Introduction  91 92 Additions  Background  Shifts  93 94  vi  LIST  OF  FIGURES PAGE  1 Block 2 The  Diagram  o f an  Inductively  3  Block  Diagram  4  ICP T o r c h  ICP-Spectrometer  Coupled of  5  Plasma  the  7  Instrumentation  24 28  5 Asymmetric  Abel  Inversion  30  6  Emission  Spectrum  a t 777  nm  (Oxygen)  33  7  Emission  Spectrum  a t 865  nm  (Nitrogen)  34  8  Emission  Spectrum  a t 820  nm  (Nitrogen)  35  9  Emission  Spectra  10 T h e  I C P when  11  Emission  12  Emission  a t 920  (Sulphur)  36  Xylene aspirated  Spectrum  a t 515  Spectrum  13 E x c i t a t i o n  nm  Temperature  14 C2 E m i s s i o n  Profiles  15  (C2  nm  a t 415  38  nm  Swan  Band)  (CN V i o l e t  Plots  ,  Band)  42 43 45 48  CN  Emission  Profiles  (1)  49  16 CN  Emission  Profiles  (2)  50  17 CN  Emission  Profiles  (3)  51  18 CN  Emission  Profiles  / Pyridine  CI E m i s s i o n  Profiles  (1)  54  20 C I E m i s s i o n  Profiles  (2)  55  21  SI E m i s s i o n  Profiles  (1)  56  22  SI E m i s s i o n  Profiles  (2)  57  19  added  52  vii  23  01  Emission  24  Sealing  25  Torch  26  C  27  of  Profiles Torch  60  Extension  ,...61  Extensions  63  Emission  P r o f i l e s with  Extension  65  01  Emission  Intensity  vs.  Viewing  Height  68  28  SI  Emission  Intensity  vs.  Viewing  Height  69  29  Lateral  30  Emission  31  01  32  Working  Curves  f o r Oxygen  89  33  Working  Curves  f o r Sulphur  90  2  SI  Emission  Intensity  Emission  Profiles vs.  Intensity  Boiling vs.  Time  70 Point when  of  the  recycled  Solute  76 78  viii  CHAPTER  I  INTRODUCTION  1.1  OBJECTIVE The  inductively  popular  as  an  excitation  spectroscopy. geological, samples.  coupled also  vast  plasma  this  of  a p p l i c a t i o n  lack  in  used  f o r the  of these  and  emission  spectroscopy  been  f o r the important  However, slow  environmental involve  inductively  (ICP-OES)  could  the development  because of organic  lines  f o r some  elements  analytical  of  f o r the determination  the introduction emission  analysis  principle,  method  very  atomic  applications  In  solutions.  i n the usual  analytical  metals.  has  of strong  particular sulphur)  with  (ICP) has become  b i o l o g i c a l  and r a p i d  i n organic  encountered  source  majority  optical  be a s i m p l e  plasma  i s widely  solutions  nonmetals  the  I t  i n d u s t r i a l ,  The  aqueous  coupled  oxygen,  region  of  of of  problems  s o l v e n t s and nonmetals ( i n nitrogen  (200-700  nm)  and  of the  spectrum. The  problems  introduction torch  and  have  been  associated diverse.  instabilities  encountered.  The  brought  degree  the  of  of  Soot  the  observation  with  of  organic  deposits  plasma  itself  molecular  atomization  on  into  solvent the  plasma  have  been  emission  has  question  and  1  nebulizers  have  not been  well  characterized  for  organic  solvents. Most sensitive region about  nonmetals resonant  (100 200  purging  to  eliminate  groups  emission  lines  requires  evacuation  of the o p t i c a l absorption  by  analytical  ICP-spectrometers 1 8 0 nm  resonant at  lines  1 7 0 nm  evacuated lines  or purged.  and  have  been  ( 7 0 0 - 950  normally  have used  accessible  below  vacuum-ultraviolet) the monochromator) oxygen.  Also,  light  below  200 nm.  Most  successfully  down  operate  so s u l p h u r ,  which  and p o s s i b l y n i t r o g e n on an i n s t r u m e n t  has  strong  with  which  of the  appropriately blazed  lines c a n be  resonant  g r a t i n g s and  and  Also,  organic  aspects  introduction into  well.  been  use w i t h  the different  reported  nm)  of wavelengths  (hence  for stable  production  introduction  easily  torch  fairly  their  vacuum-ultraviolet  (including  can  have  necessary.  and  described  region  not  a  are  developed  nonmetals  i n the  VII  For the measurement  ( 1 3 0 nm)  detectors  been  aerosol been  a t 1 8 0 nm,  and  appreciable  purged,  c a n be d e t e r m i n e d  Recently, has  becomes  when  of oxygen  special  VI  atmospheric  by  about  quartz  path  absorption  to  V,  200 nm). T h e d e t e c t i o n  nm  or  of  solvents  of  organic  the plasma  ICP e m i s s i o n  lines  have  of the  i n the f a r red to near-infrared  applications  described.  for analytical f o r conventional  This  atomic  with  gaseous  spectral  sample  region i s  spectroscopy  but i s  spectrometers.  2  This  thesis  feasibility a n  of  determining  ICP-optical  infrared  emission  emission  solutions xylene.  of  The  method where  crucial  the  in  catalyst  ICP-OES  included  has  monitoring  1.2  THE  [1] very  three  INDUCTIVELY  The atomic  gained  first  use  spectroscopy  and  Fassel  popular  precision,  [2]  process,  sources  have  been  microwave-induced (CMP),  of  an  was  but  because  with  those  near  consisted 0,  and  N  or  S  elements  application  selective recently,  of in  petroleum  nitrogen  these  potential  element  is act is  detection but  has  not  source  for  20  PLASMA  ICP  years of  ICP  excitation  independently  ago.  Since  like  dc  then  detection  versatility arc-  the  (MIP) has  by  i t has  and  been  become  limits, to  high older  spark-emission, Other  direct-current  and  Greenfield  compared  x-ray-fluorescence.  developed, plasma  an  i t s good  and  and  the  as  reported  methods  absorption  liquids  i n the  sulphur  much a t t e n t i o n  COUPLED  accuracy  atomic  plasma  where  matrix  utility  Another  the  employing  containing  of  into  nonmetals.  because  spectroscopic  in organic  test  potential  poisoners.  these  The  compounds  refining  had  i n v e s t i g a t i o n  spectrometer  1iquid-chromatography, with  an  nonmetals  lines.  organic  industry,  as  presents  plasma  plasma,  the  the c a p a c i t i v e l y - c o u p l e d most  exploited.  The  basic  spectrometer generator plasma. which  plasma  gas  pneumatic  based  on  a  the  and  tube  one  exit  PMT  can  be a  determined  grating  to  contain number can  of  be  simultaneous  a  line  either  so  to  of  have  window  i s measured,  to  of  a  as  detectors  a not  set  changes  and  the  a  the  introduced  of  by  cross-  normally  one  with  rotating  fixed of  line.  used  elements  monochromator.  i n continuum  The  which  f l e x i b i l i t y  is to  favourable  intensity  the  readers  elements  elements  in  of  a  contain  r e p o s i t i o n e d each  be  is  element  Direct  Its  can  few  or  as  determination  one  number  be  allows,  scanning just  matching  wavelength.  simultaneously.  of  box,  only  achieved  the  determination  plasma  achieved  that  with  window. T h i s  the  monochromators  corresponds  arrays  the  power  is usually  Adaption  new  sustain  spectrometer  is easily  PMTs  in  to  concentric  reading  the  radio  usually  each  flexibility  spectral  are  PMTs,  because  spectral  frequency  The  Scanning  different  of  determination  small  in  a time.  determined  Photodiode  the  a  1.  input  combination,  at  read  PMTs  for  Samples  (PMT).  emission  located  readout  element  a number  limited, the  -  different  units  I C P - o p t i c a l  necessary  n e b u l i z e r s . The  photomultiplier  of  Figure  produced  grating  slit  an  is  rates.  are  of  energy  itself  flow  which  in  the  contains  of  aerosols  shown  supplies  also  flow  are  The  control  components  time  required. observe cases,  while  a the  retaining  Also, the  is  because  analytical  background  4  Monochromator  T  Radiofrequency Generator  ICP  1  Sample Introduction  Readout  i  Sample  Figure  1.  Block  Diagram  o f an  ICP  spectrometer.  5  intensity  c a n be  However,  these  application A  i n atomic  two  essential  the  picture.  and  flow, c o i l  parts,  three  torch  i s made  gas f l o w .  the intermediate  and  i s not always  axially  through  aerosol)  energy  addition  required.  The sample  aerosol  from  the central  zone  were  observed  zone,  a c c e p t e d . Two argon-ICP  uses  a t 10  initial  versions  the  and  mm  and a t o m i c  auxiliary  of the i s  region  i s  by d i f f u s i o n a n d t h e  ionized  above  as  i t travels  emission  intensity  the load  coil  zone  and  normal  et a l .  [3]  torch  torch  the central (or  The t e r m s ,  small  load  introduced  and  energy  analytical  and a r e  generally  o f t h e ICP a r e i n use. The low  a relatively  gas  the plasma  species.  radiation  tube.  frequency  t o r o i d a l  analyte  t o 20  by K o i r t y o h a n n  into  channel  excited  ionic  coined  to l i f t  i n  quartz  at the  the radio  tube  The  i s the main  melting  t h e plasma. The s t r o n g e s t  from  plasma,  i s formed  serves  through  originates  concentric  to prevent  Energy  2.  are included  gas f l o w  from  i s atomized,  normally  three  plasma  sample  is  commercial  and t h e n e b u l i z e r  The p l a s m a  shaped  of  coil,  a r e employed:  the nebulizer  into  made.  i n Figure  tube  channel.  transferred  i s given  from  The a u x i l i a r y gas f l o w  off  y e t found  and l o a d  gas f l o w s  induction  current.  not  the intermediate  and a t o r o i d a l by  and c o r r e c t i o n s  spectroscopy.  The t o r c h  nebulizer  have  of t h e ICP i t s e l f  the outer,  Accordingly  recognized  detectors  diagram  tubes:  easily  and low f l o w  power  rates  6  Tail Plume  Normal Analytical Zone Initial Radiation Zone Induction Region Preheating Zone  Torch Gas Flows  Figure  {  Plasma Auxiliary Nebulizer  2. T h e  Inductively  Outer \ Intermediate > tubes Nebulizer J  Coupled  Plasma.  7  of  argon.  and  Radio  f r e q u e n c i e s between  the r f input  power  i s between  nitrogen/argon-ICPs  use l a r g e r  the  consists  plasma  between two  4 a n d 27 MHz  types  work the  gas f l o w  of  reported  of  have  been  coupled  reviewed  first  i n o i l were  xylene  i n 1972  a  thorough  more  for a  trace  metals  element  using  an  i n  been  a  organic  oils  metals  mobile  AND  Fassel  an of  [14,15],  phase  power  rates  and are The The  Ar-ICP  and  with  this  are concerned stated  otherwise.  and i t s a p p l i c a t i o n s  NONMETALS  f o r an  limits  i n engine  into  with  detector  flow  power  G r e e n f i e l d and  variety  High  used  [4-10].  i n 1976  reported  selective  a low  specifically  SAMPLES  investigation  kW.  are  characteristics.  [11].Detection  few  [12] and  and  t h e use of ICP-OES  given.  in lubricating  an  on  i n 1968  metals  subsequently  with  spectroscopy  ORGANIC  report  and  curves  where  2.5  MHz  b e t w e e n 4 a n d 7 kW.  different  done  plasma  TO  appeared  working  input  repeatedly  matrix Ni  was  except  APPLICATIONS  The  quite  and  torches  t o p u b l i c a t i o n s made  t h e ICP  Inductively  show  0.5  50  of nitrogen. Frequencies  and power  herein  references  type  1.3  ICPs  27 a n d  organic  f o r A l , Fe  Smith  presented  o i ldiluted  et a l . [13]  with  presented  the d e t e r m i n a t i o n  of  wear  ICP. The  determination  petroleum  products  The  use o f an  chromatography  was  reported  first  has  ICP-OES  in liquid  by  of  as  when  Gast  et  8  al.  in  1979  [17,18]. and  [16]  In  these  and  later  studies  e m i s s i o n , from  by  Hausler  and  organometallic  metals  only  Taylor  in  1981  were  used  silicon)  was  compounds  (exception  detected. Several determined  of  the  i n aqueous  demonstrated compounds  C,  H,  I , P,  nitrogen are  could  185  nm path  helium  to  emission [20],  not  ICP-OES  and  important  determined, wavelength  because region.  spectrometer  the  lines  the  They  plasma  absorption  f o r 0,  N and  coworkers far  red  to  used  these  effluents  [24,25].  and  selective  GC-effluents  using  the  by  0,  C,  F,  of  for  nitrogen  atomic  elements  oxygen  Heine,  was  used  strong  region  Br,  CI,  lines  detection  organic  the  no  molecular  also  have  and lines  Babis  and  between  120  used  and  s p e c t r o m e t e r purged  near-infrared  f o r N,  oxygen  spectral  in a series  lines  of  to  Denton  elements  vacuum  from  been  [ 1 9 ] . They  measured  [20]. A  detection  of  nm  and  have  v o l a t i l e  the  avoid  Element  660  by  of  examine  sensitive  found.  vapours and  in this  Windsor  analysis  S i . The be  and  nonmetals  to  F r y and  surveyed  as  190  and  proceeded  optical  and  S  available  Denton and  elemental  between  accessible  solutions,  introduced  wavelengths B,  easily  or  in  oxygen.  S and nine  region Br,  S,  CI  (700 C  element  -  and  with  Strong  were  papers  the  found  [21-29] 950 H  nm) were  s e l e c t i v e  gas-chromatographic  even  emission  elemental  analysis  spectroscopy  has  9  received  much  specificity plasmas their of  of  have  lower  t h e GC  then  attention, the  better  the  elements  latter  ones  Wallace of  methyl were  have  [31,32]  been  detection  limit  nitrogen  in  a  instrument.  The  to  [33], Both  100  also  ppm  been  detection  determined  vacuum-ultraviolet  d e t e r m i n a t i o n of in  the  and  sulphur,  in  were Three  limit  174.3 was  successfully  with  lines  the  the  two  solvents.  Hausler line  reported  s u l p h u r and i n aqueous  on  Bureau  xylene  around [32]  in  Of  (National  diluted  nm  only  organic  NBS  f o r sulphur. the  nonmetals  literature.  in  sulphur  elements,  lines  temperatures  been  instrument. Wallace  using  rate  s p e c t r o s c o p y has  purged  xylene  flow  a l . [30].  which  mg/1  because  for  (MIBK).  0.05  gas  higher  ketone  of  induced-  ICPs  the  the  detection  determined  o i l samples  on  matches  s e l e c t i v e  nitrogen  determined  isobutyl  tested  the  then  possess  appeared  oxygen,  have  Standards)  to  et  increases  microwave  useful  emission  Carnahan  solvents  more  MIPs  plasma  data  However,  Element  references  organic three  helium  by  J.W.  be  such  consumption  Ar-ICP.  by  Few  to  gas  and  chromatography reviewed  method.  proven  inert  because  180  or nm  reported  a  determined a  to range  purged from  nitrogen solutions  5  have using  [34,35].  10  1.4  FUNDAMENTALS  If  ICP-OES  nonmetals to  be  in  the  a  in  i s to  be  sample. However, sample  as  aqueous  solutions.  production,  the  listed  in Table  of  current  of  measured the  through  The  will  then  c r i t i c a l plasma, be  Aerosol  intensity of  a  the  the  exerted  usual  aspects and  the  on  of  aerosol  spectrum, in  an  system case  of  below  has  analyte  nebulizer-ICP  in  of  the  are light  literature.  Organic in  determination  emission  discussed  TABLE  Step  the  concentration  severe  torch,the I and  INTRODUCTION  interference effects  i t passes more  SAMPLE  successful for the  function  potentially  the  ORGANIC  organics,  simple  organic are  OF  Sample  I Introduction  Analysis  Critical  Aspect  Production  Sample D e l i v e r y Rate Nebulizer Efficiency  Torch  Soot  Deposition  Plasma  Vapour-Effect Plasma Temperature Incomplete Atomization E n t r a i n m e n t of A i r  Spectrum  Spectral Overlap with M o l e c u l a r Band Emission  11  1.4.1 AEROSOL PRODUCTION The  two  concentric w o r k on a  more  (or  the  high  nebulizer Meinhard)  less  chambers certain  are  entering  analysis  and  fraction  of  plasma,  The  VENTURI  the  radius  R  to  the  spray  the  are  the  nebulizer.  Both  is shattered droplets  distribution.  loading  effects  A  large  therefore  chamber  through  nebulized  sample  part lost the  by a  Nebulizer  larger  is  nebulizer  with  droplets  desolvation.  nebulizer  than in  the  of  the  for  the  drain.  which  a  The  reaches  efficiency.  RATE:  transport effect or  and  to  the  nebulizer  governed  by  a s p i r a t i o n  of  the  solvent ^,  and  the  driving  these  produce  avoid  the  length  pressure  variables  the  V  is  the  rate  8  Of  of l i q u i d  size  to  used  cross-flow  remove  originally  defines  d e l i v e r y  viscosity  the  leaves  gas  to  incomplete  DELIVERY  Sample  the  defined  cutoff-diameter  sample  the  of  designed  and  SAMPLE  stream  well  plasma  the  and  frequently  same p r i n c i p l e . A f l o w  velocity of  types  usually  assured  POISEUILLE  Q  i s of  defined the  by  equation. by  capillary  the L  of  P:  L  viscosity  and  possibly  the  12  pressure  difference  delivery  rates  pressure To  free  delivery  to  control  opposed  The  No  size  and vary.  the nebulizer and  therefore Also,  gas f l o w  assure  the rate.  constant  are diluted  with  an  ( s e e e.g. [ 1 3 ] ) . T h e l i m i t a t i o n s s e t by  equation  can a l s o  of sample  aspiration  be o v e r c o m e  by u s i n g  to the nebulizer  a  pump  (force-fed  as  ) ( s e e e.g. [ 3 6 , 3 2 ] ) .  EFFICIENCY: droplet  size  b u t an  concentric  operation  been  0  = 585  empirical  i s usually  thoroughly  d  i s available  o r i g i n a l l y  nebulizers  the aerosol  and t h e e m i s s i o n  model  equation,  carburetor  the f i n e r  efficiency  theoretical  TANASAWA  d i s t r i b u t i o n i s an i m p o r t a n t  since  distribution,  recently  on  o i l samples  the flow  nebulizer exact  intensities  viscous  be c o n s i d e r e d ,  the  depends  dependent  possible  to free  NEBULIZER  to  emission  solvent  POISEUILLE  sample  aspiration  rates,  appropriate the  and  difference  make  are  used  i n  examined  + 597  i s , the  to predict  be.  droplet  the  NUKIYAMA-  to  describe  designed  atomic  higher  intensity will  formula,  quoted.  parameter  I t s validity for spectroscopy  by G u s t a v s s o n  term  has  [37,38].  do = mean d r o p l e t d i a m e t e r ( m) , x> = v e l o c i t y o f g a s ( m / s ) 0* = s u r f a c e t e n s i o n ( d y n e / c m ) , = v i s c o s i t y (poise) f = density of the l i q u i d (g/ml) Q-^ = v o l u m e f l o w l i q u i d , Q = volume f l o w gas  13  cr /'and y u are  liquid  /  distribution given  varies  serves  to  Browner from  change  have  theoretical equation  [40],  effect  on  i s to  outside  Both, larger  in  'solvent  the  used  the  of  intensity  22,  water atomic  the  plasma rate  8,  6,  a  and  heating  size for  a  nebulizer  controlled 1.5  %  respectively  [41].  spectroscopy  have  to  compared i s higher.  Reviews been  on  A  reach  cause  [17],  To  used  a  from  the  Therefore used.  by  the  cause plasma  and the  the term  Nebulizer  were  reported  nitrobenzene  aerosol  compiled  and  different  water  xylene, of  can  have  rate  have  analysis  efficiency,  to  that  will  distant  been  aspiration  f o r benzene,  an  [17].  and  has  based  Taylor  [36].  effects'  published  signal  chamber  and  evaporation  efficiency  box  ICP-OES  Cresser  have  during  and  solvents  droplets  temperature  chamber  efficiency) in  a l .  analytical  spray  organic  enhancement for  chamber  spray  the  solvents  Hausler  cooled  from  predict  et  of  observed  locate  to  nebulizer  problem,  delivery  efficiencies  series  of  the  transport  emission  Boorn  a  drift  amounts  (higher  and  and  water  in  are  distribution.  equation  evaporation,  jacketed  plasma  on  solvent  an  spray  this  be  therefore  samples  size  Obviously  resultant  approach  of  original  [39],  data  overcome  and  the  presented  instabilities  to  different  evaporation  droplets  the  as  and  nebulizer. Moreover,  an  properties  production  Cresser  [38]  14  and  Browner  and B o o r n  [39,40].  1.4.2 TORCH The  design  organic  aerosols  reported tubes and  of the torch  are introduced  carbon  like  of the torch  Boumans  torch  design  [45],  The  has proven  and  deposits  when  MIBK  following  on t h e r i m s  have  aerosols  summarizes  critical  t h e ICP. F a s s e l  or xylene  Lux-Steiner  f o r organic  into  t o be  was  inner  aspirated [13], an  overcome  the  eta l .  o f t h e two  described to  when  main  optimized  this  problem  features  found  desirable:  (1)  A  Tulip that  (2) (3)  The  In  This the  tube  Tapered  of  rims  as ease  of inner  tube,  of i g n i t i o n  tube  Greenfield  provided  tube  and t h e r e f o r e  a  tube. slightly  tube.  long,  penetration  good  of  allow.  et a l . [46] suggested,  possesses  for efficient  diameter  would  located  the rim of the intermediate  the nebulizer  outer  and i n t e r m e d i a t e  the nebulizer  addition,  plasma  intermediate  as l a r g e  rim of  below  top  shaped  of  narrow  that  the  channel.  the aerosol  into  stability.  15  1.4.3 PLASMA VAPOUR  EFFECT  Boorn  AND  and  investigation itself  [36].  a  on  found, stable  t h e o r e t i c a l  solvent  factor  rate  d i d not cause  after  one  for  hour  metals  solvent  defined  efficiency  considerations.  causes  some  spatially  concluded,  that  significant pose  and  highly  a  50  the  vapour  no d i f f i c u l t i e s v o l a t i l e  without  Boumans of  resolved  MHz  with  respect  on t h e  by  torch  intensities i n  transport  solvent  vapour  i n the plasma.  data e f f e c t  In contrast,  solvents  high  they  also  was  more  power A r / N -  to the vapour  (e.g. acetone)  effect, can  be  any p r o b l e m s [ 4 7 ] .  and L u x - S t e i n e r low  loading  rate  intensities  that  emission  maximum  possible  line  expected  argued,  The  which the  The  deposits  of the temperature  low i n the plasma.  ICPs  introduced  lowering  They  rate  correlated  with  and found  than  t h e ICP  factor.  droplets.  measured  i n different solvents lower  strongly  the highest  They  on  aspiration  of the rate  carbon  extensive  solvents  evaporation  as  appreciable  solvents  From  was  aerosol  of operation.  an  t h e maximum  operation  v o l a t i l e  loading  of organic  that  from  was  which  published  i s a measure  evaporates  aspiration  have  the e f f e c t s  with  evaporation  TEMPERATURE:  Browner  They  compatible with  PLASMA  power  ICP  [45] undertook with  metals  a detailed i n MIBK  to  study find  16  optimum  analytical  respect  to flow  conditions  rates,  r f input  power,  h e i g h t . They  and  kW  f o r MIBK  aspiration  produced  conditions  to those  with  aspiration  1.4  similar  study  ketone  (DIBK)  kW.  A  diisooctyl difference xylene the in  t o an  plasma,  type  of aerosol  r f input  noise  power  ratios  aspect,  being  metals  in oils.  an  and  of about  xylene  the  ICP i s quenched  plasma.  0.5 kW These  i n p a r t i c u l a r  take  The  by  Therefore  p l a c e . Boumans  cannot a  major  'aqueous  plasma,  to refer  f o r an  this  power  plasma;  showed  higher  for that  boiling  of xylene  [ 3 6 ] , so  be a t t r i b u t e d  and L u x - S t e i n e r  one and  temperatures  factors  organic  of  generally are  studies  close  to  spatially  i n a xylene  with  to  increase signal  acquired  latter  further  the  clarify  t h e same  evaporation  of the plasma  that  to the aqueous  solvents  are very  using  temperatures  yields  0.8 a n d  f o r the determination  compared  three  even  water  alone.  [49] have  that  excitation  optimizing  To f u r t h e r  1.4  a l . [48]  t h e need  when  used  between  be u s e d  temperatures  plasma  than  must  water.  on  found,  points  effect  kW  with  r a t e and  between  again  (the terms  was  0.5  power  et  etc. will  solvent  They  the  quenching  plasma'  Caughlin  a common  i n the xylene  increase  plasma  about  information  xylene  lower  suggested  feed  similar  Miyazaki  (S/N) f o r m e t a l s .  Blades  resolved  by  introduced)  by  an i n p u t  water  aqueous  organic  that  limits)  sample  viewing 1.8  found  (detection  that  and the  to the vapour  quenching  suggested,  effect that the  17  presence the  of  organic  carrier  gas  increases requires  and  the  transport  the  thermal  higher  conditions  solvent  input  [45].  excitation  temperature  to  be  the  generally  organic highly  volatile  INCOMPLETE  and  diatomic  were  plots  CI  height  peak  at  only  nitrogen  found by  about  low  Truitt  in  to  higher load.  for  for  vapour  plasma  and  organic  that  solvents  and  causes,  the  the  plasma  can  power  when  effect  so  excitation  considered,  Whatever  given  constituents  similar  be  organic a  the  achieve  has  an  the  in and  [36]  detected  have  when  fragments  detected  along  lowest  are  Browner  observed  solvents.  to  of  of  be  limits  expected analysing  the  use  of  number  of  liquids.  species  height  molecular  sample  and  molecular  presented  of  enthalphy  ATOMIZATION:  Boorn  CC1)  presence  i t  lower  samples  increased  power  efficiencies also  to  conductivity  Also  therefore  leads  of  by  their  and  C  mm  (5mm)  containing the  plasma.  Robinson  f o r CI,  C  2  steadily  whereas the  CN  loadcoil.  solvent, Similar  with  CN,  emission  intensities  above  were  intensity  central axis  15  CH,  2  emission  measured  listed  organics  (C ,  the  2  also  an  aspirated.  The  OH,  and  NH,  bands. as  a  and  CN  NO  They  also  function for  from  increased  first  For  pyridine,  had  CN  peak  been  introduced  of  several  decreased  intense  studies  solvents  CS,  a  the to the was  conducted as  vapours  18  [50]. Emission the  determination The  presence  atomization diatomic  level  degree  matrix  when  power.  only  oxygen  a  flow  Northway is  the  (11.1  organic  might  rise the  molecule.  to  poor  nonmetals Also,  strength  the  molecular and  investigated this  from  and t h e i r  They  found at  structural  and p o s s i b l y  that  an  with  sample equal  ratio  cause  also  CO  volumes  power  the when  as  effect r f  of 0  2  height)  ratio  high  a n d CO  power  operating  are  not  2  k W.  i s not  conditions  favourable.  investigation  highest  as  o f 2:1  i s indicated for  input  other  for their the  i n t r o d u c t i o n . The  the t h e o r e t i c a l  interference when  potential  p l o t t e d as a f u n c t i o n of  input  viewing  and F r y chose molecule  from  to the  not at a l l  for different  f o r gaseous  intensities  rates,  vary  give  that  effect.  determinations  sufficient (gas  a  complex  at least  could  F r y [21] have  achieved  Therefore  achieved), This  indicates  fragmentation  o f d i f f e r e n c e s i n bond  compared  input  (although  emission  effect  emission  were  was  and  species  measuring  interference  interference  rf  of  because  Northway  gas  molecular  plasma.  of atomization  structures  oxygen  of these  the  are part  b a n d o f NH h a s b e e n u s e d f o r  of nitrogen [51].  i s obviously  i n  sensitivity, which  a molecular  i s not complete  locations  a  from  because i t  dissociation  energy  eV).  19  ENTRAINMENT When poses  OF  determining  a major  exposed  to  presented  to and  nitrogen  tubing.  oxygen,  height  explained  by  atmospheric  N> 2  when the  and  co-workers  of viewing  to  height  They  [24]. of  the  also  shown  carbon  extended of  CO2 a n d 0  also  argon  i n the tank  lack  have  [22] e m i s s i o n  gases  and  the plasma i s  [24] and n i t r o g e n  contamination  sulphur  Fry  t h e u s e o f an  to impurities  contamination  because  suggested  F r y e t a l . have  viewing  a i r .  as a f u n c t i o n and  and n i t r o g e n ,  problem,  of oxygen  atmospheric  attributed  of  surrounding  entrainment  exclude  oxygen  interference  plots  intensities this  AIR:  illustrate  extended  torch  reported  oxygen  gas  which  and l e a k a g e  that  emission  decayed torches  less were  quenching  of  was  into  the  intensities  rapidly  used. the  with  This  was  plasma  by  [24,28,52],  2  1.4.4 SPECTRUM Band spectral  emission  interference.  molecular  emission  atmospheric extension  from  gases.  to reduce  due  organics  Even to  Wallace some  CN e m i s s i o n . N a t u r a l l y , when  molecules  can cause  aqueous  molecules  plasmas formed  [53] suggested interferences  molecular  are introduced  and  considerable exhibit with  some  entrained  t h e use of a  caused  emission spectral  by NO, i s more  torch OH  and  severe  overlaps  more  20  numerous. such  Boorn  potential  investigated  and  Browner  [36]  i n t e r f e r e n c e s and  by  Xu  et  al.  have this  listed  aspect  a  number  has  also  of  been  [54].  1 . 4 . 5 SUMMARY The  l i t e r a t u r e  conclusions. could at  not  the  be  Samples  aerosol  matched  cooled  to  minimize  used.  The  degree  box. rf  of  should  by  A  input  power  should  be  the  nonmetal  chosen  lines  molecular The in  most  band  be  three  and  the  to  set  examined  to  the for  should  build  xylene spectral  in  must  be the  interference  found. be  be  up  maximize  solution be  place  matrices  aerosols  high  should  for  heat  potential  a i r must  lines  lines  reported  essentially  Secondly,  NIR  by  e f f e c t i v e  entrained  taking  chamber  organic  this  properties  to  the  A survey  carried plasma  out and  overlaps  of to the  with  emission.  study  established  An  intense had  caused  for  f o l l o w i n g  therefore  spray  torch  from  the  The  the  effects  and  special  and  to  physical  the  step,  instabilities  examined.  reported  led  of  dilution.  interference  find  because  atomization,  be  has  different  production  be  plasma  with  compared,  should  the  review  the  i n the  steps.  following chapters  First,  completeness  i n t e r f e r e n c e from  of air  analytical atomization was  was  done  lines  were  examined.  investigated  and  21  operating the of  conditions  method different  working  was  tested  optimized. Finally, by  comparing  composition,  curves  and  by  feasibility  the response  establishing  analysing  the  from  detection  certified  of  samples  limits  and  samples.  22  CHAPTER  II  EXPERIMENTAL  2.1  INSTRUMENTATION A  Figure  block 3.  diagram  The  ICP  manufactured consisted  of  by a  an  automatic  power  assembly.  A  GN  used  was  used  employed  was  the  conventional  build  up  cooled water  SC-5037).  in  the  using  0.35  a coil  m  To  of  was  was  blazed  formed  at  plano-convex focal  length.  the  Kresson  MHz,  2.5  were  and  a PT-2500  barrel  spray  Acton  a t 500  nm  was  entrance  fused  silica  The  imaging  slit  lens  The  of  Free  spray  type  of 50  distance  sample chamber  (Plasma-Therm due  to  was  heat water  tubing.  The  °C.  with used.  APCS1  Inc.,  monochromator  MA)  an  (Plasma-Therm  plastic  a p p r o x i m a t e l y 10  source  torch  chamber  wrapped  unit  plasma  instabilities  the  in  frequency  network,  mentioned.  tightly  radio  introduction.  minimize box  kW  matching  nebulizer  Czerny-Turner  Schoeffe1-McPherson, grooves/mm  N.J. T h e  concentric  plasma  temperature A  Inc.,  f o r sample  except  given  available  system glass  i s  commercially  automatic  concentric  model  a  27.18  control  was  Inc.,  instrumentation  Plasma-Therm  uptake of  was  AMN-2500E  5601)  the  HFP-2500E,  generator,  model  of  a An  the  (Model  grating image  of  270,  with the  1200 plasma  monochromator  mm  diameter  and  was  adjusted  to  by  150  a mm  provide  Sample Nebulizer and Spray Chamber  A r - Supply  I  Translation Stage  Rf- Generator  IC P  T Lens  i  Monochromator  Oscilloscope  I  <  Monitor  Figure  3.  Printer  Block  Diagram  Digital Plotter  of  the  Floppy-Disc Drive  Instrumentation.  24  an  image  magnification  by  moving  wide  and  long  pass  the  lens  wavelengths  (Opticon,  interferences.  railbed. array the  The  A l l  were  simultaneous wide was  at  900  been  The  50 was  ms  and  10  Ref.  Analog  to  achieved  Interactive output which  was was  on  digital by  with  a AI13  ms  an  of  mm.  so  from  12-bit  total  to  of  the  analog  to  an  Apple  control array  the  plane  light  which  for  was  38  be  nm  from  board  has  counters  varied  a  array  board  this  of  sensing  photodiode  circuit  and  photodiode  evaluation  i t could  off  optical  focal  of  A  order  provided  the  as  between  array  output  signal  (Kikisui,  Model  5650).  array  analog  digital  (Bata-Cynwyd,  with  the  the  i n c r e m e n t s . The  conversion  used  exit  integrated  cut  an  element  capability  that  to  lens  on  the  of  aperture.  ICP,  This  oscilloscope  acquired  acquisition  in  RC-1024SA  9316  Structures  also  1024  lOO^tm  multiple  aligned  a  altered  was  used  prevent  and  was  an  a s p e c t r a l window  an  [55],  by  elements,  2.5  adding  s i n 50  displayed  to  dimensions  of  mm  was  slit  R G 6 3 ) was  mounted  by  1  E l e c t r o n i c readout  by  in  to  nm  i n t e g r a t i o n time  increased  described  The  readout  accomplished  Reticon.  used  mm  nm.  630  height  entrance  model  mounted  RL-1024S)  25.5  viewing  The  three  detector  monochromator.  area  than  were  (Reticon  The  restricted  shorter  monochromator  1.  vertically.  i t s height filter  of  II  converter  PA). plus  The  was from  digitized  microcomputer,  operation  evaluation  readout  board  of,  and  data  (including  25  integration 6502  machine  (signal  was  data  were  or  Apple a  language  done  The  monitor,  driven  A  region to  Further  Basic.  converter  data  subtraction, Spectra  by a  processing  Abel  inversion  and  processed  f l o p p y d i s c s and d i s p l a y e d on  on a d i g i t a l  box  was  plotter  mounted  by a s t e p p e r  City,  PA)  motor  which  stage  of  thus  of the plasma.  the microcomputer  on  (WATANABE  a  axis  WX 4 6 7 1 )  I n c . model  4979,  movement  i n increments  o f 0.0127  of  the  observation  The t r a n s l a t i o n  so t h a t  translation  horizontal  movements enabled  linear  (Daedal  allowed  to the optical  combination  translation  to analog  (OKIDATA 9 2 ) .  perpendicular mm.  background  i n Applesoft  plasma  Harrison  program.  s t o r e d o n 5 1/4 i n c h  printer  stage  and t h e d i g i t a l  averaging,  etc.)  the  time)  stage  i t s movements  lens  and the  o f any was  could  desired  interfaced be  software  controlled. A Bay,  piston  pump  NY) w a s  delivery  used  was  (model  NH-SY,  i n experiments  employed.  of a i r contained  solvent  downstream  The  argon  chemicals was  used An  were  supply  from  were  Inc.,  Oyster  controlled damped  sample  by  a  i n a syringe connected  few  to the  t h e pump.  was o f w e l d i n g  generally  Metering  where  Pulses  m i l l i l i t r e s line  Fluid  used.  A  grade  mixture  and r e a g e n t of xylene  grade  isomers  as the s o l v e n t . r f i n p u t power  o f 2 kW w a s u s e d  throughout  the study  26  and  the  and  2  the  viewing  2.2  TORCH  plasma  l/min  The from  height  in  Steiner rates  Figure  [45].  of to  well  be  via  given.  It  % a  in  power  as  found  et of  aspiration  rate  of  Plasma  by  l/min  rate  and  al.  to  carbon 0.1  and  of T1.0.  one  h o u r . The  Using  their  Lux-  aspiration the  torch Xu  et  plasma  on  the  same  for via torch  at  a  when the  torch  was  rates  [36]  [54]  into  least  flow  and  compares al.  aspirated  Browner  acetone  and  aerosol  tolerated  deposits  features  extinguished  data  the  the  of  on  was  No  with  ml/min  are  our  water  torch  Boorn  dimensions  high  authors.  plasma  operated  shop  Boumans  buildup  nebulizer. our  by  criteria  mixed  glass  extinction  soot  Ar  UBC  some of  tolerate  other  MHz  that  Model  to  the  The  aerosols  both  was  a period  Therm  12  gas f l o w  at  shows  without  to  27  when  free  for  torch  Using  acetone  Xu  nebulizer  designed  used  their  water  r a t e s were  tubing.  organic  was  operation  nebulizer  The  concentric  was  flow  constructed  solvents  those  1  plasma  4.  tubes.  that  than  acetone  It  The  quartz  r e s i s t a n t  with  reported  a  was  for  organic  intermediate  rf  torch  desirable  gas  varied.  precision-bore  found  more  auxiliary  respectively.  quartz  provided  and  and  70  % and  reported  c o n t r o l l e d a  cross-flow  they  working  used  was  conditions  27  and  criteria,  delivery  rate  it as  was  found  h i g h as  0.4  that  our  ml/min  assembly  tolerated  acetone.  T  F i g u r e 4. I C P T o r c h Dimensions: A 2 0 . 3 7 mm, B 17.39 mm, C E 1.48 mm, F 20 mm, G 20 mm, H 43 mm, L 1 mm, M 3 mm.  15.86 mm, D 5 I 20 mm, K 25  mm, mm,  2.3 ACQUISITION OF EMISSION PROFILES After emission The mm 100  translation each  to  allow  stands  position  xn.  calculate position are in 100  radii  5  the  this to  (r) l e f t  Abel  measured  represent and  100  of  of  lateral the  as  the  plasma.  sum  of  emission  as  lateral  a  [56]  The  from  the  The  in  Figure  intensity  was  d i s t a n c e s . The  0.1905  then of  radii  used  so  5. at to  radial hereby  intensities  emission  at  intensities  function  data.  of  of  manner.  intensities  illustrated  calculated  right  increments  the  Inversion  profiles  following  emission  lateral  intensities  the  in  width  plasma  height,  i n the  represented  observed  emission  equivalent Figure  of  Asymmetric  from  the  profiles  f o r the  moved  measurement  across  depth  viewing  acquired  was  the  lateral the  desired  were  stage  locations  through  the  intensity  obtained  Ixn  choosing  intensities  Irn on  centre.  29  Figure  5.  Asymmetric  Abel  Inversion.  30  CHAPTER RESULTS  3.1  NEAR-IR  The were  used  for  the  our  work  as  most  overlaps of the  0.75  nm  the  a survey  these  lines  molecular  was  employed  agreement was  the  [ 2 1 ] . An  However,  the  plasma  oxygen  weak. T h e  Fry  most  intense  emission  01  et  A  these  are  components  01  and  to  potential  mm  1 %  find  spectral  gas  flow  from  the  that line  oxygen  i s not with  rate  top  thus  be  the  of  of  777.2 atomic  i n xylene  resolved the  described  spectral  could  gaseous  out,  found  lines,  of  to  Since  studies.  line  system  free  opposed  emission of  7 7 7 . 2 nm  experimental  10  lines  sulphur.  nebulizer of  NIR  and  on  [21,22,28]  analytical  carried  a l . i t was  7 7 7 . 5 nm  lines  check  spectrum  The  777.4 a n d the  for  as  was  height  with  i n F i g . 6.  by  lines to  of  nitrogen  species.  coil  For  selection  and  LINES  his colleagues  oxygen,  a viewing  provided  for  of  sensitive  nearby  other  of  SULPHUR  and  f o r the  and  provided  AND  Fry  l/min  line  oxygen  guide  DISCUSSION  involved nebulizing xylene  with  load In  a  determination  sampling, the  AND  OXYGEN, N I T R O G E N  p u b l i c a t i o n s of  III  from  resolution  i n Chapter  overlaps used  is  from  as  a  II. the  group  determinations.  nitrogen, 868.0 nm  a l l lines line  was  were most  found  to  be  intense, again  comparatively in  agreement  31  with  Fry  et  overlap  with  dynamic times. nm  to  are  a l . the  range Fig.  880  The  the  the  The  immediate  821.6  nm  the  nm  line  nm  Arl line  line  at  long  NI  spectrum triplet  figure.  NI  As  line  nitrogen. region  however,  866.7  NI  868  in  of  practice,  emission  821.6  determinations in  the  i s an  identified  In  intense  of  7  nm.  overlap  [22].  plot  the  the  of  of  this  line  i s about  half  as  the  nm  range  of  used  Arl  848 line  partial  analytical  emission  i s provided  intense  the  from  this  for  the  wing  integration  nearby  result  was  A  in  line  restricted  array  and a  a  as  spectrum in Fig.  8.  868.0  nm  the  line. For again  sulphur,  in  agreement  quantitative 905 is  nm  and  932  partially  a  input  nm  i s given  overlapped system,  spectrum It  with  from  should power,  be  pure  high  960  was  observed  adopted  was for  molecular  not  in Figure  as  shown  xylene that  band  significant  emission  No  9.  Arl  and  under flow  under  rate  nm  922.8  the  line  and  nm  line  with  our  subtraction visible.  low  effect  of  the  working  low  875  this  to band  conditions  interference  analytical  rf  viewing  about  the  the  for  between  line  from  spectral of  used  c o n d i t i o n s of  (stretching  any  SI  922.5  the  intense,  spectrum  The  this  most was  i n F i g . 9,  makes  other  with  found  emission  [57]. However,  analysis.  band  An  nebulizer  C^-Phillips  was  [28],  the  noted,  the  emission  Fry  with  but  height, nm)  line  determinations.  experimental of  921.3  lines  from was  32  found.  F i g u r e 6. E m i s s i o n S p e c t r u m a t 777 nm. A e r o s o l : X y l e n e 1 % 0 a d d e d a s I s o p r o p a n o l . I n t e g r a t i o n t i m e : 750 ms. D a r k c u r r e n t was s u b t r a c t e d .  with  33  a CN  o  oo  vD  00  CN  00  00  00  1-1  5  <  A  O  •  CO vO • •  00 00 00 vO \D vO 00 00 00  z z z  0>  CN  CO  00  en  M  z  •  O roo  vO  A  CN  •  r-H  CT\  •  rH  r-» oo  r-» oo  M  H  z z z  L a 848  880  WAVELENGTH  (NM)  F i g u r e 7. E m i s s i o n s p e c t r u m a t 865 nm. Aerosol: 1 % N added as t r i e t h y l a m i n e . I n t e g r a t i o n t i m e : Darkcurrent was subtracted.  Xylene 1.5 s.  with  34  833  803  WAVELENGTH  (NM)  F i g u r e 8. E m i s s i o n s p e c t r u m a t 820 nm. Aerosol: Xylene 1 % N a d d e d a s t r i e t h y l a m i n e . I n t e g r a t i o n t i m e 1.5 s. Darkcurrent subtracted.  with  35  m  vo O  oo cr\ i n  vD r-» 00 CJ> O O O O  o> »  1^ »  *  Lil  905  WAVELENGTH  c: T  332  (NM)  F i g u r e 9. E m i s s i o n s p e c t r a a t 9 2 0 nm. I n t . t i m e 750 ms. A: A e r o s o l : Xylene with 1 % S added as diphenyld i s u l f i d e . Darkcurrent subtracted. B: Aerosol: Xylene. Darkcurrent subtracted. C: S p e c t r u m B s u b t r a c t e d f r o m A, s h o w i n g t h e p a r t i a l l y overlapped S I 9 2 2 . 8 nm l i n e .  36  3.2  PHYSICAL  When the  APPEARANCE  xylene  appearance  to  the  or  of  aqueous  schematically  the  in  Q>2 S w a n  band  the  plasma,  on  at  organic  plasma  changes  515  An  above  core  with  nebulizer  flow  rate  more  volatile  than  xylene,  of  this  nebulizer load  green  gas  coil  for  emission  is  emission  due  This on  flow  visible  stretches  the  0.8  to  the  to the  this  tip  green  emission  core rate  Intense  is  up  in  and  was of  1/min.  when  violet  rim  above  outside  system  plasma  The  15  becomes  bottom  of  in  the  xylene, coil  mm  is  of  increases which  rim,  nm  to  length  plasma  415  due  also  load  at  the  and  and  For  the  at  the  channel  torch  of  compared depicted  solvents,  and  the  i s  tube.  aspirated.  1/min  aspirated,  emission  around  central  Above  CN  green  torch  the  just 0.4  plasma  nebulizer  are  the  the  the  is  dramatically  visible  also  on  a l l along  solvent  organic  10. nm  sides  just  "XYLENE-PLASMA"  other  Figure  the  channel of  any  THE  plasma.  the  aerosol  OF  are the  for  above  a  the  no  green  but  violet  observed.  more  intense  top.  37  Violet  Green  Figure  10.  The  ICP  when x y l e n e  is  aspirated.  38  3.3 COMPLETENESS OF ATOMIZATION Atomization obviously with the  not complete.  nonmetal  sought  a  Both  aspects,  region  spatial  emission  from  have  that  might  energies The some  Table  other  The  when  this  higher  molecules  from  of these  than  detected  likely  their  ionization  i s  complete. and  of  and Ar  Several  the  might  molecules charged  ionization energies.  emission  [36]  are l i s t e d  some  i s  data  i n the plasma.  the dissociation  dissociation  the  h a s t o be  neutral  present  were  emission  data  by t h e i r  the  was  are present  because  i s  originates  to p o s i t i v e l y  t o be  energy  element  atoms.  emission  i s unlikely  species  with  which  of emission  molecules  tool  interpreting  i s  either  of atomization,  f o r the temperature  by i o n i z a t i o n  i f ,  are present  available  Spatial  ICP  interfere  i n the  atomization  Molecules  a measure  diatomic  nonmetal  and t h e c o r r e s p o n d i n g  by e m i s s i o n .  are generally  not  emission  molecules  obvious  of view.  However,  II along  energies.  The  disappearance  be c a u s e d  does  the  particular  atomic  where  t o be c o n s i d e r e d  with  molecules.  that  of the completeness  molecules  be d e t e c t e d  Further,  of  i . e . which  point  correlated  particular  i n the plasma  examined. from  this  i n  f o r i s not incorporated  dependance  therefore  points  of a  or i f the observed  from  molecules  However,  (i.e. atomization  complete),  and  organic  the determination  present  not  of  in  ionization  included  for  39  comparison.  TABLE  Dissociation  Molecule  and  Ionization  Dissociation Energy (eV)  (Ar)  II  Energies  f o r some  Molecules  Ionization Energy (eV)  15.8  [58]  CO  11.1  [21]  14.0  [59]  N  9.8  [22]  15.6  [59]  CN  8.2  [59]  CS  7.6  [60]  c  6.5  [60]  NO  6.5  [60]  °2  5.1  [21]  12.2  [59]  OH  4.4  [60]  CH  3.5  [47]  11.1  [59]  2  2  40  3.3.1  E M I S S I O N FROM D I A T O M I C  The nm  was  a c c e s s i b l e s p e c t r a l range searched  several  f o r molecular  viewing  background already violet  band,  band  a t 415  nm  OH  and  molecules  region  (200  insensitive for  their  searching  -  400  compared  f o r CS  nm)  bands  nm  and  11  and  pure  a n d OH  which  investigations. Therefore,  other  [36],  CH, 1,3-  isopropanol  were  r e s p e c t i v e l y ) . These explanation  CH a t 4 3 0 nm)  the  violet  %  but another  (except  CN  bands  12. T h e  (50  the  the  t h e CN  and  at  i n the  emission  detected  and  where  t o t h e PMT  structure  and Browner  be  absent,  bands  t o 1000  but besides  molecular  by B o o r n not  been  a l l these  band  Swan  a t 515  to xylene  have  and  i n Figures  could  added  might  be, t h a t  band  200 nm  ripp1e-structure  identifiable  reported  NO,  when  Phillips  Swan  2  about  spectral regions,  a r e shown  propanedithio1  a  C  species  aspirated  2  no s t r o n g The  diatomic  C  from  emission  Faint  i n many  mentioned  found.  could  heights.  occured  were  CS,  MOLECULES  PDA  Boorn this  i s  l i ein  r e l a t i v e l y  and Browner data  i s not  used very  conclusive.  41  CM m  ON  m  i—i  m  525  490  WpVELENGTh  F i g u r e 11. C Swan b a n d a t I n t e g r a t i o n t i m e : 750 ms. 2  515  nm,  C NM3  Aerosol:  Xylene  42  WAVELENGTH  F i g u r e 12. CN V i o l e t I n t e g r a t i o n t i m e : 50  band ms.  at  415  nm.  (NM)  Aerosol:  Xyl  3.3.2 EMISSION PROFILES Excitation plasma 13  by  Blades  because  a  distribution the  and  in  power  obtained  the  main the  can  induction  region, with  the  more  be  zone  increasing  pronounced  be  and  than  the at  the  but  1.25  an  axial  i s high  at  the  for  profiles.  in  Figure  the  discussion for  2  the not  was  there  should  not  1.75  kW  region. low  the  axial  in  the  toroidal  be  plasma.  toroidal  of  kW,  work,  a  trends  xylene  this  and  profiles  the  temperature  Data  In  indicated lower  of  needed  Caughlin,  for  reproduced  throughout  Temperature  but  are  distinguished:  height.  lower  height.  acquired,  and  temperature  generally  with  used  acquired  picture  will  d i f f e r e n c e to  regions  [49]  presented  Blades  substantial  Caughlin  ICP  level  by  profiles  q u a l i t a t i v e  subsequently  input  is  temperature  region  a Two  above  In  the  toroidal  heights  and  decreases  region  region  below can  the  be  10  temperature  but mm  increases were  expected  to  not be  heights.  44  7000  7000  E00O  E000  5000  5000  cr  cr  a. s: LU  LU  4000  4000  SOOO  3000 8  6  4  2  •ISTRNCE  0  2  FROM  4  6  PXIS  8  (MM)  8  6  4  2  DISTPNCE  0  2  FROM  4  E  PXIS  S  (MM)  7000  EOOO  5000 LU ££  I— cr LU  a. z: LU  4000  iii 3000 8  E  4  2  DISTPNCE  0  2  FROM  4  E  PXIS  8  (MM)  F i g u r e 13. F e l E x c i t a t i o n T e m p e r a t u r e p r o f i l e s o f t h e ICP when x y l e n e i s a s p i r a t e d , a : 1.75 kW, b : 1.25 kW. ( i ) 10mm, ( i i ) 15 mm a n d ( i i i ) 20 mm f r o m t h e l o a d coil. Taken from B l a d e s and C a u g h l i n [ 4 9 ] ,  The torch The  following  rim,  which  nebulizer  that  the  torch  rim  was  gas  t i p of  profiles  flow  the  and  located rate  green  that  C  were  a l l acquired  above  4 - 5  mm  load  was  adjusted  core  2  above  was  influence  the  the coil.  to  0.70  1/min,  visible  2 mm  above  could  show  up  so the  in  the  for  the  measurements. The  wavelengths  acquisition III.  A l l  the  the  by  were  subtracting  The  viewing  its  that  are  Species  C  2  Conditions  with  for  nm  for  the  indicated  Wavelength  516.5  are  intensity  TABLE Experimental  times  used  provided  in  variations  close  to  the  Table  in  the  analyte  value.  heights,  point,  profiles  corrected  measuring  and  reference  integration  presented  profiles  background line  of  and  the  top in  of  the  the  loadcoil  as  profiles.  III Acquisition PDA  of  the  Integration  Profiles Time  50  ms  (Fig.  14)  250  ms  (Fig.  26)  CN  421.6  nm  250  ms  CI  907.8  nm  150  ms  SI  921.3  nm  1500  ms  01  777.5  nm  1000  ms  46  C  2  AND  Lateral  CN  EMISSION  emission  Emission  from  C  profiles  agree  PROFILES  profiles  is limited  2  with  the  of  to  C  2  the  visually  are  given  central  in  Figure  channel  observed  and  extent  14. the  of  C  2  emission. The some  plots  CN  probably argon  in  the  is  due  supply.  layers from  of  the  width  of  xylene  CN  central to  ICP  CN  plasma  originate  the from  emission must  at  be  larger 10  central the  at  15, low  16  %)  caused  by  heights. causes at  (Figure  the  formed  emission  channel  sample  is  and  17)  heights,  impurities in  a i r . This  (approximately in  (Figures  channel  nitrogen  which  surrounding the  emission  Strong  the  intensities must  of  on  extends  high low  which  xylene  nitrogen  Adding  show  the  and outer  entrained across  pyridine CN  the to  emission  heights,  which  18).  47  CZ  5MM L  C2 7MM <_  CO  10  10  > I— cr _J LU  or 10  0  E  4  2  DISTANCE  0  2  FROM  4  G  RXIS  B  1  0  (MM)  A 10  8  6  DISTPNCE  C2 9MM l_  > t— cr _i LU  10  8  E  4  DISTANCE  Figure  2  0  2  FROM  4  G  RXIS  14. L a t e r a l  8  10  (MM)  C  2  4  emission  profiles.  2  . 0  2  FROM  4  E  RXIS  8  (MM)  10  CN 5MM  CN 7MM  co to  co co  UJ  >  i— cr _i  UJ  10  8  6  4  2  in 0  DISTANCE  FROM  CN  10  8  G  4  DISTANCE  Figure  2  2  4  6  PXIS  8  10  (MM)  A  10  8  6  4  2  DISTANCE  9MM  0  2  FROM  A 0  2  FROM  4  E  AXIS  8  10  (MM)  CN 11MM  4  G  PXIS  15. R a d i a l  8  10  (MM)  CN  10  8  E  4  DISTANCE  emission p r o f i l e s (1)  2  0  2  FROM  4  S  AXIS  8  (MM)  10  CN  CN 15MM  20MM  CO  co  > I— cr _i UJ  m  T-lJjftHI«10  8  E  4  DISTANCE  Figure  2  0  2  FROM  4  S  AXIS  16. R a d i a l  8  10  (MM)  CN e m i s s i o n  10  8  6  4  2  DISTANCE  profiles  (2)  0  2  FROM  4  6  AXIS  8  (MM)  10  CN  Figure  35MM  17. R a d i a l  CN  CN  emission  profiles  (3)  40MM  CN  5MM P  CN  7MM P  co CO  >  -A10  8  6  4  2  DISTANCE  11 0  FROM  CN  10  8  6  4  DISTANCE  2  2  4  t— cr _i LU DC  6  AXIS  8  10  10  (MM)  8  6  4  DISTANCE  9MM P  0  2  FROM  4  2  0  2  FROM  4  6  AXIS  8  10  (MM)  CN 11MM P  6  AXIS  8  10  (MM)  F i g u r e 1 8 . R a d i a l CN e m i s s i o n 10 % p y r i d i n e a d d e d .  10  8  6  4  DISTANCE  profiles  2  0  2  FROM  when  4  6  AXIS  8  (MM)  10  The SI  are  show  o f CI e m i s s i o n  i n Figures emission  a l l heights. weak  SI EMISSION PROFILES  profiles  emission  xylene) at  C I AND  i n Figures  19 a n d 20 a n d o f  21 a n d 22 ( 2 0 % d i m e t h y l s u l f o x i d e i n  from  the t o r o i d a l  In the c e n t r a l  low i n the plasma  channel,  and i n c r e a s e  region  of the  emission with  plasma  intensities  height.  53  RELATIVE EMISSION INTENSITY  Figure  20.  Radial  CI  emission  profiles  (2)  SI  5MM  SI  in in  7MM  in in  10  8  6  4  2  0  DISTANCE  2  FROM  SI  4  6  AXIS  8  10  10  (MM)  8  6  4  2  DISTANCE  0  FROM  SI  9MM  2  4  6  AXIS  8  10  (MM)  11MM  in in  in in  LU UJ  cr LU  10  8  6  4  DISTANCE  Figure  21.  2  0  2  FROM  4  6  AXIS  Radial  8  10  (MM)  SI  emission  10  8  6  4  2  DISTANCE  profiles  0  2  FROM  4  6  PXIS  8  10  (MM)  (1)  56  SI  Figure  22.  15MM  Radial  SI  SI  emission  profiles  20MM  (2)  57  3.3.3.  CONCLUSIONS  Emission sample,  C  central agrees of  C  and  2  with  channel  height  this  where  profiles  low  intensities  the  extent  height  suggests,  height  rate,  height.  molecule  the This  core  CN w i t h  a  i n the central  that  atomization i s  presumably  as t h e l e n g t h  low i n  of the green  i n the aerosol  of atomic  emission  low i n the c e n t r a l  channel.  depends  The  on t h e  of the visible  C  2  of molecular  emission.  that  the sample  the aerosol The  central  fact,  originates  The o c c u r a n c e  independent  diffuses  a t low h e i g h t s ,  i s not complete,  from  interference  comply  region very  well  of  with  emission  of the plasma  rapidly  sideways  channel.  that  channel  o f CI and SI showing  channel,  CI and SI i n t h e low t o r o i d a l  indicates, from  extent  the strong  i s achieved,  gas flow  increasing  o f 8.2 e V , d i s a p p e a r e d  a certain this  with  from the  changes. The  from  that  originating  was o b s e r v e d  observed  The f a c t  energy  above  nebulizer  pyridine,  the visually  above  complete  species  but disappeared  emission.  2  molecular  CN f r o m  channel  dissociation  core  from  from  the toroidal incomplete  of viewing  where  most  atomization  of the atomic  region,  implies,  atomization  in  the  emission that  i s small  an and  height.  58  3.4 OPTIMIZATION  3.4.1 ENTRAINMENT OF AIR 01 Figure  emission 23.  profiles  Oxygen  plasma,  right  height,  more  travelled  is  at  observed  the  and  torch  more  further  taken  four  at  the  rim  oxygen  towards  at  the  outer  (5  has  heights  mm).  are  given  layers  of  With  been  in the  increasing  entrained  and  has  centre.  3.4.2 EXCLUSION OF AIR A by  first  simply  the  placing  torch.  efficient rapidly the  It for  with  and  the  exclude how  very  any  the  extension With  It  that  this  piece  found  that  exclusion  of  deposits  of  entrainment  quartz  this  a i r and  when lines  of  "add-on"  extensions  found  carefully  oxygen.  that to  Figure  extensions  the 24  were  i n F i g . 24  extension  such  i n place  a  torch  is a  the  also  in  straight plasma  not  Different tested  to  could  be  to  bore  had  to  completely  drawing the  very making  extension  schematic  of  was  then  order  to  top  xylene,  carbon  torch  made  blackened  were of  connected is a  on  impossible.  deposition  was  device  aspirating  analyte  the  tube  crude  of  was  shown  eliminate  short  whether  prevented. sealed  a  carbon  sizes  determine  to  was  observation  shapes  be  attempt  showing  torch. quartz  The tube.  changes i t s  59  Figure  23.  Radial  01  emission  profiles.  -5 o o o  —4  2 J  •3  Figure 24. T o r c h a n d c o n n e c t o r s h o w n w i t h s t r a i g h t tube extension i n cross sectional view. 1. S t r a i g h t tube e x t e n s i o n . 2. T o r c h . 3. C o n n e c t o r ( T e f l o n ) w i t h r u b b e r 0r i n g s . 4. L o a d C o i l . 5. P l a s m a a s d e p i c t e d b y i t s e n v e l o p e of green Co e m i s s i o n . 6. Torch holder. 7. Bore f o r a d d i t i o n a l s n e a t h i n g a r g o n ( s e e t e x t ) . D i m e n s i o n s : A: 25.5 mm B: 22 mm C: 150 mm D: 2 0 . 3 7 mm.  61  appearance. cm  high  The v i s i b l e  persists  up  extension.  Green  restricted  to below  the  extension.  Although extension, did  not change  alters  very  blacken  spread tube.  25a  When  C  i s no  2  i s no  longer  i t se x c i t a t i o n An e x a c t ,  longer  observed. with  the  characteristics  spatially  because  above  extensions  the  resolved extension  very  rapidly.  the plasma  wall  of  from  as e x t e n s i o n  coil  the  were  carbon coating  tried  the plasma  t o be gases. carbon  tends  within  to  a few  deposits the entire  are depicted as i n F i g s .  badly  and  oxygen  t h e t o p as i n F i g . 25c  arrived  got  by  blackened  a t , was  and t o i s o l a t e  the extension  of  the extension  but the wall  finally  found  the buildup  to f l i c k e r  Narrowing  efficient,  The s o l u t i o n tube  which  was  atmospheric  eventually  the wall  i s not complete.  of  the load  formation,  and downwards,  a n d 25b c a u s e s  to  xylene,  cm  i n i t i a l  of Fig.24  exclusion  susceptible  25. R e m o v i n g  straight  by  3 - 4  the top of the  i t sappearance  extension  three  The d i f f e r e n t  the  that  f o r the  the extension  from  changes  tube  made  the  emission  aspirating  After  exclusion  CN  i s not possible  i s very  upwards  Fig.  beyond  about  characteristics.  a t about  minutes.  in  however,  effective  deposits.  1 cm  only  the torch r i m but extends to the topof  found  straight  However,it  normally  caused  significantly.  optical  The  emission  plasma  i t was  evaluation,  to about  Violet  the  tailplume  to use  the plasma  introducing  argon  62  A  C  \  /  torch D: 70 mm  extensions. E : 38 mm  -B-  Figure 25. Cross D i m e n s i o n s : A: 22 F : 150 mm G: 33 mm  s e c t i o n a l view mm B: 25.5 mm C:45 H: 45 mm  of mm  63  (approximately connector  This  extension  free  problems  i n  sputtering  into  arrangement  of carbon  be  found. that  present.  extension  build  up  since  found  to  be  a  was  s e t up  keeps  also  other  major  when  half  precursor  of  C2  where n o t  to the wall  molecule,  No  f o r this  profiles  the s e n s i t i v i t y  dicarbon  of the  occasional  The r e a s o n  close  and  xylene.  at locations  o f C2  i n the  torch  aspirating  radial  C2  hole  between  although  shows  showing  a  the lower  observed.  The p r e s e n c e  an  gap  occured,  F i g 26.  explains  through  the  deposits  operation  with  normally the  tangentially  of the plasma  not  acquired  1/min)  ( s e e F i g . 24)  extension.  could  2  of i t to  of  soot  acetylene, i s  f o r the formation  of  soot  [60].  3 . 4 . 3 AMBIENT OXYGEN AND NITROGEN Oxygen pure argon prevented, in  and n i t r o g e n e m i s s i o n  plasma, so  the argon  different even  when  those  tanks  entrainment  elements  tanks. were  These used.  through  with  molecular  the solvent  contamination  must  I t was  be  present  were also  contains  sieves  f o r several  effectively,  observed  so  even  of atmospheric  amounts  of s p e c t r o s c o p i c grade,  Treatment  was  oxygen  gases  to that  that  reduce  this  vary  this  as  xylene,  i n some  ( 3 A) a n d b u b b l i n g hours  was  as i m p u r i t i e s  found  found,  i nthe  form.  nitrogen oxygen  contribution  i s  64  C2  5MM  C2  EX  15MM  C2  10MM  EX  EX  CO CO  10  8  6  4  DISTANCE  2  0  2  FROM  4  G  B  AXIS  F i g u r e 26. R a d i a l C extension i n place.  10  (MM)  2  emission  profiles  with  straight  tube  65  small  compared  i t s e l f .  to  the  Therefore  determinations nitrogen  amount  found  a l l xylene  was  treated  emission  could  used  that be  i n the  way.  pure  for No  argon  the  subsequent  increase  detected  plasma  when  in  ambient  xylene  was  height  were  aspirated.  3 . 4 . 4  OPERATING  Rf  input  optimized in -  Rf  the  for  input  gas  maximum  flow  VIEWING  rates  intensity  original  Plasma  at  the  2  and the  REGION  and  with  viewing  the  adopted  extension  of the  12  green  C  gas  interdependent.  2  flow  found  i t was  to  left  at  flow  rates did  significantly  and  and  viewing  area:  rate  rate  Emission of  the  gas  p r o f i l e s  not  were  left  Because  core i n the n e b u l i z e r channel  2  flow  center  Both  1/min. rate  flow  nebulizer  i n t e n s i t y  were  therefore  flow:  intensity  and  argon  nebulizer  several  intensities  power,  argon  emission  argon  the  load  auxiliary  nebulizer  along  Emission  kW.  original  Nebulizer  tip  power:  strongly with  influence  -  power,  AND  place.  increase  -  CONDITIONS  i t  and  was  intensities plasma  were  rises  expected,  viewing  height  versus  flow  rates.  Vertical  are  given  in  Figure  27.  the  would  be  height  acquired  oxygen  with  that  viewing  therefore  the  for  emission The  peak  66  intensity rates peak 28)  exept  shows  that the  highest  nitrogen element  emission  the  o f 0.5 l / m i n plot  intensity  that  found  rate.  the best  f o ra l l f l o w gave  (Fig.  somewhat  higher  A quick  survey  viewing  i n the region  maximum  f o r sulphur  for a  and n e b u l i z e r gas f l o w  i s also  the radial most  from  intensity  height f o r  o f a f e w mm  profiles  nonmetal  emission  the central  channel,  intensity  observation slight  rate  A similar  emission  suggested,  that  originate  h e i g h t o f 3 mm  above  coil.  Because suggest,  A flow  intensity.  height  load  at a viewing  0.4 l / m i n .  emission  viewing for  was f o u n d  were  obtained  o f f the central  d i p a t 5 mm  was  found,  (section  a t low h e i g h t s lateral  was  does not  profiles  ( F i g 29) t o c h e c k  axis  desirable.  and o b s e r v a t i o n  was  o f SI whether Only  a  made a t  centre.  67  I  1  1  1  I  0  3  6  9  12  I  15  I  I  18 21  I  I  24 27  I  30  Height Above Loadcoil (mm)  F i g u r e 27. O x y g e n e m i s s i o n i n t e n s i t i e s a l o n g t h e c e n t r a l a x i s when x y l e n e m i x e d w i t h o c t a n o l (1 % o x y g e n ) a s p i r a t e d . Straight tube e x t e n s i o n i n p l a c e . Four d i f f e r e n t nebulizer gas f l o w r a t e s were e m p l o y e d . • - 0.4 l / m i n A - 0.5 l / m i n • - 0.6 l / m i n x0.7 l/min  68  Height Above Load Coil (mm) F i g u r e 28. S u l p h u r e m i s s i o n i n t e n s i t i e s a l o n g t h e c e n t r a l a x i s when d i p h e n y l d i s u l f i d e i n x y l e n e (1 % sulphur) a s p i r a t e d . F i v e d i f f e r e n t n e b u l i z e r f l o w r a t e s were employed. A0.4 l / m i n 0 ~ 0.5 l / m i n 0.6 l/min ^ - 0.7 l / m i n A ' - 0.8 l/min  69  Figure  29.  Lateral  SI  emission  profiles.  70  3.4.5.  CONTROLLED  The  use  nebulizer  of  of  the to  increase  (and  (up  a f t e r  rates  5  was  controlled  promises  to  3  also  than  feed  rate.  was  time  a  sample  to  memory  to  free  of  rates  samples of  intensities  ml/min) the  tend  the  reduce  delivery  optimization  Signal  found,  the  an  to  to  properties  delivery  due  flow  sample  e f f i c i e n c y ) independent  rate.  min)  sample  inconsistent  allows  with  nebulizers  greater  This  to  changing  (approximately  concentric  sample  physical  flow  strongly  It  control  nebulizer  gas  rates  chamber.  due  v i s c o s i t y ) and  nebulizer  s i g n a l  to  attempted.  effects  rate  delivery  DELIVERY  pump  d i f f e r e n t  (especially delivery  a  was  interference because  SAMPLE  that get  not  to  reach  effects  the  stable  very  long  in  generally  when For  high  a  the  capillary  rate.  found  relatively  became  damaged  uptake  At  were  from  spray  tips  force-fed  these  of at  reasons  employed.  3.4.6. C O N C L U S I O N S The  torch  viewing spatial to and  extension  height  for  dependance  oxygen of  and  us to  entrainment  d i s t i n g u i s h ambient argon  allowed  oxygen  and  to  establish  evaluate of  an  the  extent  atmospheric  nitrogen  in  optimal  the  gases  and and  solvent  supply.  Compromise  operating  conditions  adopted  for  the  71  determination kW,  plasma  rate  2  The  6  torch  done  where  C  core  2  flow  above  gas  the  torch  The  the  oxygen  extension,  i n t e r f e r e n c e from  mostly  were  from  the  sulphur,  neutral  high  attempted  as  found  agrees energy  low  in  as  with  lines  the  usually  oxygen  was  2  the  mm  the  and below  could  best  be  viewing  torch  intensities height  shown  data  above  rim,  atmosphere.  viewing  region,  emission  of  the  high  ionization  0,  or  has the  viewing  height  caused  by  decreasing  emission  well  their  Therefore,  the  0.5  nitrogen  below  flow to  was  the  2  in  of  two  originating  s e c t i o n  presented  [ 6 2 ] , An  the  for  other  explanation  is  follows.  Ionization  S  found  peak  toroidal  and  gas  2 mm  which  because  i s no  the  was  power  set  line  and  loadcoil, of  input  was  about  coil  there  that  rate  sulphur  elements  fact  to  rf  auxiliary  flow  load  Determination the  and  extends  rate.  above  were:  l/min,  these  nonmetals  N  12  nebulizer  3 mm  rim.  elements  for  The  for  mm  without  height  The  lines  three  flow.rate  for this  measured nitrogen  the  visible  coil  the  gas  l/min.  l/min. load  of  been  energies, detected  decrease above  nonmetals  the  of  and for  nonmetal  height  of  gradual  i o n i z a t i o n ,  fraction  of  the  is  unlikely,  no the  of  emission  from  Ar-ICP  [21,22,28].  emission  intensity  peak  intensity  but  must  nonmetal  because  being  be  ionic  with  cannot due  excited.  to  be a  This  72  agrees most  with  of the nonmetal  temperature The two  optimal  more  toroidal level  more  fraction  decreases  best  viewing  oxygen  because  higher  fraction  of  originates,  height  i t can  each  line.  decreases  present  as w e l l . height the lower  of sulphur  the  i s probably other.  where  excitation  which  to  into  does  with  species  explain  state  the hot  i s presumably  state i n the  height which  as  i s higher level  by  increasing  the upper  steadily  f o r sulphur upper  With  The t e m p e r a t u r e  analyte  This  determined  diffuses  get e x c i t e d  emission  of  region,  height.  of the a n a l y t e  where IR  i n the t o r o i d a l  counteract  r e g i o n however  the  excited the  which  of the near  toroidal  with  viewing  and  region  that  emission  decreases  mechanisms  height  that  the fact,  and  so  gets  well,  why  than  for  therefore  excited.  73  3.5  ANALYTICAL  3.5.1  R E S P O N S E FROM D I F F E R E N T  Whether on  the nonmetal  the sample  response same  of a  amount  compound. %  PERFORMANCE  nonmetal the  of  solutes  lower  than  compounds higher,  nonmetal  were  containing 200°C,  was  the  a l l of which  contained  the  i n form  1 % oxygen, prepared  on  the b o i l i n g  a  different  3 % nitrogen  and  had  the found  that  boiling  point  emission  or 1  respective  the v o l a t i l i t y  e x h i b i t e d . The n o n m e t a l  the lower  of  I t was  nonmetal,  a dependence  dependent  comparing  measured.  the  was  by  but  thus  intensity  intensity  investigated  containing  i n xylene emission  was  of s o l u t i o n s  the  Solutions  sulphur  emission  composition series  COMPOUNDS  when  points  of  these  intensity  of the nonmetal  was  parent  compound.  VOLATILE  Table  IV  containing response the of  SOLUTES  gives  the  a  l i s t  nonmetals  of  which  f a c t o r s . I n F i g . 30  nonmetals the parent  are plotted compound.  logarithmic,  therefore  decrease  50°C  of  i n  were  v o l a t i l e tested  the emission  as a  function  Note, this  the  that  effect  b o i l i n g  and  of the b o i l i n g  i s very  their  intensities  the i n t e n s i t y  point  solutes  point  scale i s  pronounced,  causes  of  roughly  a a  74  TABLE Volatile  Compound  Oxygen 01 02 03 04 05 06 07 08  containing  Nl N2 N3 N4 N5 N6  51 52 53 54  compounds as  containing  compounds  Di-n-hexylamine N,N-Dimethylacetamide Cyclohexylamine Pyridine Isobutyronitrile Triethylamine  Sulphur  containing  Solutes  B.P. (°C)  Dimethylsulfoxide 2-0ctanol 2-0ctanone Acetic Acid Anhydride Isopropanol Methyl-ethy1-ketone Methanol Acetone  Nitrogen  IV  compounds  Dimethylsulfoxide 1,3-Propanedithiol Sulphur-I-chloride Tetrahydrothiophene  1 % 0 in  Relative Response  xylene  189 177 170 139 82 80 65 56  as 3 % N i n  1.5 1.4 1.8 3.3 36 21 71 43  xylene 1 .5 1 .5 2 .8 4 .6 8 .3 9 .8  192 165 134 115 107 89  as  1 % S in  189 169 138 119  xylene 1.14 1.07 1.8 2.6  F i g u r e 30. N o n m e t a l e m i s s i o n i n t e n s i t y a s a boiling p o i n t o f t h e s o l u t e s . Compounds and p o i n t s see T a b l e IV.  function boiling  of  the  76  fivefold  increase  Whether chamber,  was  effluent  from  nebulizer ml/min the  was  then  tested  the  (2-octanol  °C  and  oxygen time  the  acetone  each.  in  Fig  The  -  177  -  56  higher  intensities  whereas  the  relatively is  the  cause  compound while likely  high  of  waste  vapour.  dependent  on  points  Fig.  besides  in  the  properties are  the  for  30  do  boiling must  and  not  point f a l l  points an  which  of  °C, to  3  methanol  -  yield  %  decayed but  The  1  versus  compounds  gave  rapidly,  remained  at  redistribution  nonmetal  stream  parent  to  the  torch  substance.  The  most  is  that  droplets  the and  evaporates,  the  on  smooth  is  volatile reach of  curves.  Because  the  course  compound. However,  solutes,  influence.  was  intensities  lower  of  the  rate  the  boiling  Therefore,  effect  into  differing  xylene  then  started  waste  through  boiling  aerosol  amount  The  cycled  82  emission  that  the  exert  to  loses  from  was  -  aerosol  this  boiling  ml  the  for  The  added  interference. in  nebulizer  manner.  widely  longer.  effluent  plasma  10  lower  ones  the  delivery  isopropanol  the  in  reintroduced  The  with  oxygen  enriched  evaporate  was  about  first  this  compounds as  of  that  explanation  following  were  volatile  becomes  the  of  °C,  at  effect  system.  °C)  levels  an  the  compounds  show  less  by  chamber  pump  plots  31  in  volume  Four  intensity.  caused  spray  total  assembly.  points 65  a  emission  this  using  and  in  the  Therefore,  other  compound  the  standards  of  77  0  10  20  Time (min)  F i g u r e 31. D e c a y o f o x y g e n e m i s s i o n i n t e n s i t i e s when s a m p l e r e c y c l e d from the spray chamber d r a i n o u t l e t back trough n e b u l i z e r . 1 % oxygen i n x y l e n e . % - methanol •-isopropanol A -acetone • - 2-octanol.  78  different  molecular  percentages different  of  amounts  The  vapour  but  also  on  the  the  depends  amount  contains  varying  molecular  of  of  SOLUTES  Compounds  boiling  gives Again, %  a  list  the  sulphur  some  with  detectable a  of  capillary  of  and  accordingly  added  the  the nature the  points  to  xylene.  boiling of  the  in  point  volatile  plasma  again  higher  Problems  1 %  as  vapour  dependence  they  with  200°C  effect.  which  oxygen,  occurred  because  concentric  than  enhancement  n o n v o l a t i l e compounds  solids, the  on  the nonmetal  volatility  i n xylene.  of  were  reaching  solutions contained  the  only  and  different  structure. N O N V O L A T I L E  show  contain  element  not  sample  amounts  they  substances  concentration  The  the  nonmetal  of  pressure  species.  of  the  structure  were  d i d not Table  tested.  3 % nitrogen the  tended  V  or 1  s o l u t i o n s of to  clog  the  nebulizer.  79  TABLE V Nonvolatile Compound  Oxygen  B.P. (°C)  containing  compounds as  Nitrobenzene 3-Phenyl-l-propanol Phenol 8-Hydroxyquinoline N-Methy1-N-nitroso-p-toluenesulfonamide  Nitrogen  containing  compounds  Nitrobenzene Diphenylamine Bipyridine Azobenzene N-Methy1-N-nitroso-p-toluenesulfonamide  Sulphur  Solutes  containing  compounds  Diphenyld'isulf ide Diphenylsulfoxide N-Methy1-N-nitroso-p-toluenesulfonamide  Relative Response  1 % 0 i n xylene 210 235 solid solid  0.96+/-0.07 0.97+/-0.07 0.96+/-0.07 1.05+/-0.07  solid  1.04+/-0.07  as 3 % N  i n xylene  210 solid solid solid  1.1+/-0.1 0.9+/-0.1 1.0+/-0.1 0.9+/-0.1  solid  1.0+/-0.1  as I I S i n x y l e n e solid solid  1.00+/-0.02 0.99+/-0.02  solid  1.01+/-0.02  80  Note, of  these  f a l l the  on  that  i n F i g . 30  nonvolatile the zero  volatiles  nonvolatile It  was  determined, switchover samples.  droplets  long  those  would  emission appear  of the l o g scale. are  given  intensities  as u n i t y , i . e .  The i n t e n s i t i e s  as  multiples  of  of the  response. found,  that  the time of  because  nonvolatile a  i s much  when  observation  only  with  one a s s u m e s  from  times  stable  shorter  i s consistent  effect  This  when  to reach  samples  switchover  system,  line  are flushed  droplets.  standards  therefore  This  volatility  the nonmetal  that  explains  experienced volatile  signal than  for  with  compounds  vapour less the  were  after  the above  the nebulizer also  samples  the  volatile  described and  rapidly  small than  particularly  t h e pump  delivery  had been  used f o r  experiments.  81  3.5.2  AMOUNTS  The  AMBIENT  amounts  solvent 2.7  OF  OXYGEN  of ambient  NITROGEN  oxygen  and  the  argon  supply)  % oxygen  and  8.1  nitrogen  %  AND  and  were  nitrogen  typically  aspirated  as  (from  the  equivalent  to  nonvolatiles in  xylene.  3.5.3  SIGNAL  TO  Signal 0.0057  BACKGROUND  to  and  background  1.4  respectively, nonvolatiles. counted  3.5.4  as  f o r f o r  ratios  were  oxygen,  an  Ambient  RATIOS  n i t r o g e n  analyte  amounts  determined  as:  and  sulphur  concentration  of oxygen  and  0.064,  of  1  nitrogen  %  were  background.  DRIFTS  Drifts detection  of  uncertainty exceeded A  of s i g n a l i n t e n s i t i e s a l lthree  of  the  random  major  elements.  measurements  noise  contribution  intensities.  the  to background  found oxygen  to  increase  and s u l p h u r  by  In  found  was  introduced  This  lines  %  drift  i s not  ratios.  1.5  a  and  by  of  these  the  surprising  %  cases  the the  drifts  signal.  Background 2.8  to a f f e c t  a l l three  f l u c t u a t i o n s of the  background signal  were  continuum considering  intensities  i n one  respectively. This  hour  amounts  at  were the  to the  82  equivalent  of  oxygen  sulphur  and  background by  0.6  at  % per  nitrogen.  intensities  hour  The  nm  the  to  amount  background,  argon  of  % and  line  was  s l i g h t l y  found  exceeding  no  drift  to  oxygen  %  to the  of  found  (from  measured  solutes.  to about  intensity  s u p p l y ) was  0.02  nonvolatile  i s equivalent oxygen  whereas  0.2  nitrogen  which  ambient  and  of  respectively  t h e 820  xylene an  the  to  The  decrease  1 %  measured  impurities  decrease over increase  ambient  in  time  of  the  nitrogen  was  detected. Intensities samples nitrogen this  appeared i s not  to  be  rather  available  correct  use  f o r these  analytical  because  the  line.  drifts  as  sulphur  contained  in  Corresponding data f o r  limited  work  was  done  with  A  assembly.  temperature  The  to about  nebulizer  50°C  must  change  cooling  of  sufficient  to  decreased  i n a l l three  compared  to  overcome  the  ICP  pure  this  of  the  spray  problem.  plasma.  concerned,  close  these  to  the  drifts  nebulizer box  and  was  was torch  found  i n use. H e a t i n g of  transport  spectral  argon  for  plasma  was  the  was  background  reason  i n the  the  background  the  stability  when  assembly  implemented  of  suspected  thermal  a l l o w e d us t o m o n i t o r  f a r as  intensity  insufficient  the  stable.  of a photodiode array  measuring  rise  and  element. The  by  due  the  efficiencies  and  chamber  not  Background  regions  to  with  Therefore,  an  was  intensities sample  load  increase  in  83  the  background  However,  this  intensity  a  et  intensities  3.5.5  a t 820  decreasing  also  a l . have o f up  DETECTION  with  nebulizer  efficiency.  a decreasing  background  nm.  are not unusual  problem  Lorber  to a  i s not c o n s i s t e n t  found  Drifts pose  points  i n ICP e m i s s i o n  when  aqueous  reported  a  to 5 % within  spectroscopy  samples  drift  of  and  are  analyzed.  metal  emission  30 m i n u t e s [ 6 3 ] .  LIMITS  OXYGEN: The a  emission  nonvolatile  of  the  standard,  photodiode  approximately line.  The  readings  experiment.  was  as  of the  because The  measured.  was  set to  the ambient standard  of  as  nitrobenzene,  The  integration  2.5  s  oxygen  deviation  yielded  at the  analyte  concentration of  20  the  time  equivalent  concentration,  a s : 1.0 g / 1 o x y g e n  was  consecutive  d i d not i n f l u e n c e  short  time  which  The d r i f t s  concentration  of the ambient  determined  was  array  of the array.  readings  f o r 1 % oxygen  75 % s a t u r a t i o n o f t h e a r r a y  noise  determined  noise  intensity  duration to three  these  of  the  times  the  the detection  limit,  i n xylene.  84  NITROGEN: The  detection  similarly  using  nitrobenzene was  found  limit it  the  16  f o r nitrogen than  f o r nitrogen  821  i n xylene  t o be  i s higher  l i m i t  nm  line,  was  with  3  and an i n t e g r a t i o n  g / l nitrogen i n water  %  nitrogen  time  i n xylene.  could  determined as  o f 3.0 s . I t  The  detection  n o t be d e t e r m i n e d ,  because  50 g / l .  SULPHUR: The  detection  emission the  limit  intensity  background.  equivalent  intensities. mg/1  limit  efficiency done  reported  VI  VUV  were  times  0.125  of  %  sulphur  as  %  sulphur  as  used  t o measure  were  i s poorer  as t h e  the noise  0.5  mg/1  i s better,  determined  and  limits  and 390  i n water  f o r xylene  f o r xylene Table  i n water  i n xylene  of  xylene  The d e t e c t i o n  sulphur  detection  acid  i n  was  to three  S o l u t i o n s  d i p h e n y 1 d i s u 1 f i d e sulfosalicylic  f o r sulphur  determined  sulphur because  the  line  a s : 120  i n water.  The  the transport  and t h e o p t i m i z a t i o n  was  aspiration.  summarizes values  the detection  f o r xylene  limits  and g i v e s t h e  f o r comparison.  85  TABLE  VI  Detection  Limits  Nonmetal  Solvent  NIR  (PDA)  Oxygen  Xylene  1.0  g/1  Nitrogen  Xylene  16 g/1  Water  >50  Xylene  120 m g / l  Water  390 m g / l  Sulphur  When has  comparing  amplifiers, the or  noise an  determining  improve  can  Detection  limits  of  of necessary  a  lack The  guideline. averaging limits. rates,  An  Then, load  be  their  expected could  t h e use of a o f t h e NIR  a  sensitivity to  be  n o t be  PMT  lines  three  sharp  of  orders  drop  of  f o r t h e 920  relatively  determined,  poor. because  equipment.  increase  limits  of  random  provide  i n t e g r a t i o n noise  an o p t i m i z a t i o n  power  have  photon  on t h e n a t u r e  by p e r h a p s  a l l PMTs  detection  decreases  limit,  limits  limits, i t  are inherently  i s not. Depending  so t h a t  f o r PMTs  measured  t h e PMTs  mg/l [33]  detection  f o r the detection  However,  line  0.05  a n d VUV  detection  a t 9 0 0 nm,  sulphur  100 m g / l [ 3 2 ]  the detection  PDA  those  magnitude.  sensitivity nm  t h e PDA  intensified  might of  while  that  (PMT)  g/1  t h e NIR-  t o be c o n s i d e r e d ,  VUV  and v i e w i n g  and  time  a  or  improves  of working height)  only  rough signal  detection  conditions  for signal  to  (flow noise  86  ratio  most  proper  likely  optimization  because  i t i s  interact.  sometimes Not  eV  to  the figures conditions  the  one p a r a m e t e r  an  optimum. "Simplex  For  state  energy  levels  this  f o r other  made  3.5.6  on  this  WORKING  [21,22,28],  An  nonmetal  lines  trivial  does n o t  reason,  i s  a  therefore  conditions [64],  limits  follow  the order  of the r e s p e c t i v e  estimate  A  parameters  a r e : 7.9 e V f o r s u l p h u r , 10.7 e V f o r o x y g e n  f o r nitrogen  well.  i s not  at a time  Method"  the detection  as  different  t o o p t i m i z e ICP working  surprisingly,  limits be  how  changing  a i d , the  used  t h e upper  which  clear  lead  mathematical  improve  of the working  not  Simply  necessarily  of  would  of xylene  i n the near  lines,  and  11.8  detection  infrared  could  basis.  CURVES  OXYGEN: Working  curves  f o r two  3 - p h e n y l - l - p r o p a n o l ) and two and  acetic  shown and  acid  anhydride)  i n F i g . 32. T h e  linear  produced  curves,  linear  curves  "nonvolatile" "volatile" oxygen  nonvolatile while  the  ( n i t r o b e n z e n e and  (dimethylsulfoxide  containing substances  volatile  but at higher  compounds gave  identical  compounds  overall  are  s t i l l  intensities.  87  NITROGEN: Working of  curves  the r e l a t i v e l y  for nitrogen  low  were  not acquired  because  sensitivity.  SULPHUR: Working  curves  dimethylsulfoxide in  Figure  were  f o r found  both t o be  dipheny1disu1fide linear  and  are  and  presented  33.  88  Oxygen in Xylene  (%)  F i g u r e 32. W o r k i n g c u r v e s o f oxygen i n x y l e n e . #- N i t r o b e n z e n e , *'- 3 - P h e n y l - l - p r o p a n o l A - Dimethylsulfoxide, m~— A c e t i c a c i d anhydride  89  0 . 0 6 2 5 0.125 0.25  Sulphur  F i g u r e 3 3 . Working curves +- D i p h e n y l d i s u l f i d e ,  0.5  I  2  4  in Xylene (%)  f o r sulphur i n xylene. Q- D i m e t h y l s u l f o x i d e 90  3.5.7  CERTIFIED  As the  a  final  check  determination  standards were  from  FOR  SULPHUR  o f t h e u s e f u l n e s s of t h e method f o r  of sulphur  t h e US  i n o i l samples,  N a t i o n a l Bureau  of  five  certified  Standards  (NBS)  tested. The  effects extent A  O I L STANDARDS  standards due  of  to  this  working  diluted  different dilution  curve  diphenyIdisulfide listed  were  i n xylene  physical was  from  properties.  limited 0.0625  i n xylene  was  to minimize  by to  However,  the detection 2  %  matrix the  limit.  sulphur  as  e m p l o y e d . The r e s u l t s  are  i n Table VII.  TABLE V I I NBS Standard Dilution (g/50ml) 1620a  5  1621b  10  1622b  5  1623a 1624a  %  S  Samples  found  4.1+/-0.1  %S  c e r t i f i e d  4.504+/-0.010  Accuracy  91  %  0.80+/-0.02  0.950+/-0.005  84  %  1.9+/-0.1  1.982+/-0.018  96  %  20  0.15+/-0.02  0.240+/-0.001  63  %  neat  0.065+/-0.02  0.141+/-0.002  46  %  91  As  a  comparison  concentrations  shows,  more  the standards  VII,  accuracy  =  concentration). efficiencies, the  plasma  nebulizer in  two  the  diluted  determined This  strongly  of  were  and  the  more  (see l a s t  points  amounts  reduced  column  Whether  this  of  to reduced  of the samples  delivery was  true  certified  accurate  concentration in %  i.e. reduced  because  determined  the r e s u l t s  were  efficiency.  rates was  the  i n Table certified transport reaching and  /  or  investigated  ways.  Three check  of  of the samples  were d i l u t e d  whether a decrease  accuracy.  The  results  by a h i g h e r f a c t o r  in viscosity  are given  TABLE  below  would  increase  i n Table  to the  VIII.  VIII  Dilutions Standard  1620a  1621b  Dilution  5 g/50ml  4.1  2 g/50ml  4.5 0.80  5 g/50ml  0.88  5 g/50ml  1.9  2.5  The increased  g/50ml  accuracy t o above  0.950  1.982  2.1  improved 100  % S certified  4.504  g/50ml  10  1622b  % S found  i n two  cases  and  Accuracy  91  %  100  %  84  %  93  %  96  %  106  %  i n one c a s e i t  %.  92  A second of  sulphur  is  recovered,  for  the  curve are  check  as  was  done  then  the  another  matrix  in  Table  If  a  standard  a l l of  the  transport efficiency  used  given  making  diphenyldisulfide.  solutions  and  by  for  the  effect  acquisition must  take  addition  added  sulphur  i s the  same  of  working  the  p l a c e . The  results  IX.  TABLE Standard  IX Additions  Recovery of added Sulphur  Dilution  1620a  5  g/50ml  0.50  %  94  %  97  %  2  g/50ml  0.20  %  95  %  105  %  1621b  10  g/50ml  0.10  %  86  %  98  %  1623a  20  g/50ml  0.10  %  69  %  91  %  the  (Table  When  account  accuracy  samples  sulphur  closely. into  the  certified  added  Addition  Corrected accuracy (see t e x t )  Standard  Comparing  the  when  the  standards,  IX,  corrected  as  of  (Table IX)  determination  with  recovery  VII)  of  calculating errors  sulphur  shows  recovery  the  the  that  the  the  become  the  these  added  sulphur much  match  sulphur  i s  of  (see  the  quite taken  concentrations  smaller  in  in  Table  accuracy).  93  An  other  interference were when  higher pure  these  i n d i c a t i o n i s the fact  when  f o r that  the d i l u t e d  xylene  was  Standard  Dilution  1620a  5  g/50ml  5  g/50ml+0.5  2 2  background  intensities  samples Table  were X  measured  gives  a  than  l i s t  of  a t 920  nm  when  X NBS  standards  i n xylene are a s p i r a t e d  Background (% BG)  Increase ( a s % S)  4.6  0.033  4.5  0.032  g/50ml  2.4  0.017  g/50ml  1.0  0.007  3.1  0.022  2.8  0.020  10  g/50ml  10  g/50ml+0.1  % S  % S  5  g/50ml  1.4  0.010  5  g/50ml  2.8  0.020  1.7  0.012  3.8  0.027  4.6  0.033  2.5  g/50ml  20  g/50ml  20  g/50ml+0.1  Generally with  the  s h i f t s .  Shifts  1623a  e f f i c i e n c y  aspirated.  Background  1622b  transport  NBS  TABLE  1621b  a  aspiration  % S  background rate  when  intensities organic  were  solvents  found were  to  decrease  introduced.  94  Therefore,  the  the  load  sample  efficiency. for  the  affect  higher in  the  Higher  less the  monitoring  plasma  diluted  This the  background and  background  measured  subtracted.  the  intensity,  the  smaller  intensities  NBS-samples.  quantities  effect  the  were  These  smaller  transport  indeed  shifts  found  did  not  because  the  background  was  again  the  importance  of  shows  background  the  intensity  to  obtain  accurate  results.  ones 1:100  Generally,  the  of  [32]  Wallace  with  xylene  for  four  not  compare  the  the  concentration  The  f a c t  with  a  %  that  that  the  values  containing  standard and  sulphur  compounds  in  the the  The  102  %  in  the  (Wallace but  response  did took  sulphur of  the  sample).  one  occured. the  diluted  highest  the  the  accuracies  curve,  NBS-samples  in  with  when  e x p e r i m e n t a l l y  (except  redistribution  nm.  and  with  particular the  180  working  measured  well  standards  at  samples  of  volatility  line  85  concentrations certified  VUV  102,  100 on  a  compare  NBS  97,  the  as  obtained  similar  were  NBS  of  standards  for  using  standards  accuracy  other  results  case)  determined did  means  Therefore,  o i l samples  not  must  the be  exceed that  no  sulphur of  low  volatility.  95  CHAPTER  IV  CONCLUSION  Oxygen first used  time for  1.0  an  with the  nitrogen as  in  organic  ICP-OES.  sulphur.  g / l , 16  The  g / l and  nitrogen  and  sulphur  emission  lines  proved  than  respective  detection purging  of  linear.  A  because  of  working the  in  relatively  low  be oil  effects.  necessary  be  to eliminate  nonresonant  less  does  sulphur  sensitive  not  were was  the  require  some  not  a  f o r that  even  Bureau though  to  effects  be  element. of the  Not a l l  eliminate  addition 10  to  acquired  limitations.  of about  interference  found  (National  the standard  factor  oxygen,  However,  diluted sufficiently  A dilution  determined  These  successfully,  Therefore  as  for  sensitivity  caused  well  path.  o i l standards  sensitivity could  lines  were  xylene  lines.  nitrogen  for  as  were  much  curve  low  used.  t o be  and  relatively  t o be  in  mg/1  f o r oxygen  determined  had  120  the l i g h t  was  interference  limits  f o r the  lines  element  detection  therefore  of  certified  the samples  that  emission  r e s p e c t i v e l y .  Standard)  of  of  near-infrared  curves  determined  vacuum-ultraviolet  or e v a c u a t i o n  Working  Sulphur  the  was  Near-infrared  determination  and  the  liquid  method  i s deemed with  the  to NBS  samples.  96  The  entrainment  interfere because were  with  the  found  the  of  a i r  into  determination  highest  emission  low  the  in  the  of  oxygen  intensities  plasma,  plasma  where  did  and  nitrogen,  for these that  not  elements  effect  i s  not  significant. Atomization regions to  be  where  A  so  comparison  boiling of  the  systems  that  such  a  effect  points  as  below to  by  introduction for  matrix  improve  the  rate  for  Detection better  the  matching  at the  aerosol  detection  xylene limits  diffusion  plasma  was  effect  standards,  °C  chamber  were  shown due  to  Such  a l .  plasma  by  be  the  could sample  also  be the  the  could  sample the  need  interference likely  would  the a s p i r a t i o n natural  improved low  by  reported  forced  very  because  liquid  chamber  eliminate  and  than  in  was  the  defined  plasma  various  step  into  the  also  somewhat  limits  well  spray  Direct  the  higher  or  system  [65],  production limits  the  a  This  a  compounds  detection  into  would  imposed  can  of  disclosed  when  used.  species  directly  et  probably of  the  originates  selective  limitation.  into  of  elimination  Lawrence  effects  200  element  samples  recently  in  interference  nonvolatile  nebulizing  this  an  i n the spray  The  overcome  emission  series  chromatography. the  samples  is unlikely.  of  method  organic  nonmetal  atomization  redistribution  use  the  atomic  complete,  incomplete  with  of  by  one.  assuring  toroidal  region  97  of  the  plasma  combination  with  by  a  forced  low  nebulizer  sample  gas  flow  rate  i n  feed.  98  BIBLIOGRAPHY  1.  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