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The conductivity of amino acid solutions in high electric fields Terentiuk, Fred 1949

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THE CONDUCTIVITY OF AMINO ACID SOLUTIONS IN HIGH ELECTRIC FIELDS by FRED TERENTIUK A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS IN THE DEPARTMENT SEPTEMBER, 1949 -2. I ABSTRACT The purpose o f t h i s i n v e s t i g a t i o n was t h e developement o f a d i r e c t method o f i n v e s t i g a t i n g the e l e c t r i c a l conductance o f a m p h o l y t i c s o l u t i o n s i n h i g h e l e c t r i c f i e l d s . T h i s was a c h i e v e d w i t h the use o f a cathode r a y o s c i l l o s c o p e , w h i c h r e c o r d e d the conductance as a f u n c t i o n o f t h e f i e l d s t r e n g t h o v e r a wide range. A maximum f i e l d o f 180,000 v o l t s p e r c e n t i m e t e r was a p p l i e d . I t was shown t h a t a l i p h a t i c ampholytes, such as g l y c i n e , v a l i n e , e t c . , i n aqueous s o l u t i o n , e x h i b i t a c o n s i d e r a b l e i n c r e a s e o f conductance w i t h r i s i n g f i e l d s t r e n g t h . F u r t h e r i n v e s t i g a t i o n s , e s p e c i a l l y w i t h p o l y p e p t i d e s , a r e p l a n n e d . The consequences o f t h i s , i n v e s t i g a t i o n f o r the b i o p h y s i c a l problem o f p e r m e a b i l i t y i n l i v i n g m a t t e r i s d i s c u s s e d . I I ACKNOWLEDGEMENT T h i s i n v e s t i g a t i o n has been u n d e r t a k e n on the s u g g e s t i o n o f Dr. 0. B l u h . I am g r a t e f u l t o Dr. B l u h f o r h i s permanent i n t e r e s t i n the p r o g r e s s o f the work, and f o r many h e l p f u l d i s c u s s i o n s . I am i n d e b t e d t o Mr. H. H. A. D a v i d s o n M.A.<~who.ldeveloped a g r e a t p a r t o f the e l e c t r o n i c s o f the a p p a r a t u s , and t o Mr. H. D u t t o n M.A. f o r h i s h e l p d u r i n g the p r e l i m i n a r y s t a g e s o f the work. T h i s r e s e a r c h was c a r r i e d out under a g r a n t t o Dr. B l u h from t h e N a t i o n a l R e s e a r c h C o u n c i l o f Canada. A summer s c h o l a r s h i p f r om the N a t i o n a l R e s e a r c h C o u n c i l e n a b l e d me t o f i n i s h t h i s work d u r i n g the summer months. B o t h th e s e g r a n t s from t h e R e s e a r c h C o u n c i l a re g r a t e f u l l y acknowledged. CONTENTS Page ABSTRACT I ACKNOWLEDGEMENT I I ILLUSTRATIONS. I l l I . OBJECT OF THE INVESTIGATION 1 1. I n t r o d u c t i o n 1 2. The Wien E f f e c t s 2 3. Amino A c i d s 3 I I . APPARATUS 5 1. P u l s e G e n e r a t o r 5 2. C o n d u c t i v i t y C e l l 9 3. V o l t a g e M e a s u r i n g D e v i c e 13 4. P h o t o g r a p h i c R e c o r d i n g 13 I I I . EXPERIMENTAL PROCEDURE 14 1. S o l u t i o n s 14 2. E l e c t r i c F i e l d Measurement 15 3. L i n e a r i t y o f M o d u l a t i o n and P u l s e S l o p e 15 IV. RESULTS 17 1. Method o f I n t e r p r e t a t i o n 17 2. R e s u l t s o f Measurements 18 3. D i s c u s s i o n o f R e s u l t s 28 V. CONCLUSIONS 30 BIBLIOGRAPHY 33 I l l ILLUSTRATIONS F i g u r e S u b j e c t Page 1. B l o c k Diagram o f A p p a r a t u s 6 2. P u l s e G e n e r a t o r C i r c u i t 7 3. A p p a r a t u s 10 4. C o n d u c t i v i t y C e l l 11 5. C i r c u i t o f V o l t a g e M e a s u r i n g D e v i c e 12 6. S k e t c h F o r C o r r e c t i o n o f P u l s e B unching 19 7. 5,000 Ohm R e s i s t o r 22 8. Barium F e r r o c y a n i d e 22 9. B a r i u m F e r r i c y a n i d e 23 10. L i t h i u m Bromide 23 11. Magnesium S u l p h a t e 23 12. P o t a s s i u m I o d i d e 24 13. H y d r o c h l o r i c A c i d 24 14. A c e t i c A c i d 24 13. G l y c i n e 23 16. A l a n i n e 25 17. / S A l a n i n e 25 18. V a l i n e 26 19. G l u t a m i c A c i d 26 20. P r o t e o s e Peptone 26 21. Bacto Peptone 27 22. Bacto T r y p t o n e 27 23. Serum 27 THE CONDUCTIVITY OF AMINO ACID SOLUTIONS IN HIGH ELECTRIC FIELDS I . OBJECT OF THE INVESTIGATION 1. I n t r o d u c t i o n I t was found by Wien (1,2,3,4,) t h a t a t h i g h e l e c t r i c f i e l d s t he conductances o f s o l u t i o n s o f e l e c t r o l y t e s a r e no l o n g e r c o n s t a n t i n accordance w i t h Ohm's l a w but i n c r e a s e w i t h t h e f i e l d . T h i s d e p a r t u r e f r o m Ohm's l a w i s known as the Wien e f f e c t . A b r i d g e method was used by Wien and h i s co-workers t o e i t h e r measure d i r e c t l y t h e conductances a t v a r i o u s e l e c t r i c f i e l d s , o r t o compare t h e conductances o f one e l e c t r o l y t e r e l a t i v e t o a n o t h e r e l e c t r o l y t e . The purpose o f t h i s i n v e s t i g a t i o n has been t h e developement o f a r a p i d and d i r e c t method o f i n v e s t i g a t i n g the Wien e f f e c t i n e l e c t r o l y t e s and e s p e c i a l l y ampholytes such as amino a c i d s . S h o r t p u l s e s o f v o l t a g e a r e s u p p l i e d t o the c o n d u c t i v i t y c e l l c o n t a i n i n g the e l e c t r o l y t e o r ampholyte the p u l s e s b e i n g modulated l i n e a r l y w i t h v o l t a g e s f rom 0 t o 10,000 v o l t s . The c u r r e n t s p a s s i n g t h r o u g h the c e l l pass a l s o t h r o u g h a s m a l l r e s i s t a n c e i n s e r i e s v / i t h the c e l l , and the v o l t a g e d rops a c r o s s t h i s r e s i s t o r a r e a p p l i e d t o t h e v e r t i c a l d e f l e c t i n g p l a t e s o f a cathode r a y o s c i l l o s c o p e . The p u l s e l e n g t h can be v a r i e d o v e r a wide range w h i l e t h e f r e q u e n c y o f p u l s a t i o n i s v a r i a b l e f r om 200 t o 20,000 c y c l e s p e r second. P h o t o g r a p h i c r e g i s t r a t i o n i s used. 2. The Wien E f f e c t s The i n c r e a s e o f conductance w i t h r i s i n g e l e c t r i c f i e l d s t r e n g t h has two causes w h i c h a r e e x p l a i n e d e i t h e r by the i n t e r i o n i c a t t r a c t i o n t h e o r y o r by a t r u e d i s s o c i a t i o n e f f e c t . The i n t e r i o n i c a t t r a c t i o n t h e o r y assumes t h a t s t r o n g e l e c t r o l y t e s a r e c o m p l e t e l y d i s s o c i a t e d i n s o l u t i o n . E a c h i o n i s su r r o u n d e d by an i o n atmosphere o r i o n i c c l o u d w h i c h , on the av e r a g e , w i l l i n c l u d e more i o n s o f t h e o p p o s i t e s i g n . I f a p o t e n t i a l g r a d i e n t i s i m p r e s s e d on the s o l u t i o n , an i o n w i l l t e n d t o move i n one d i r e c t i o n w h i l e the i o n i c c l o u d a s s o c i a t e d . w i t h i t w i l l t e n d t o move i n the o t h e r d i r e c t i o n . Thus the i o n i s d i s p l a c e d f rom the c e n t r e o f i t s i o n i c c l o u d , g i v i n g r i s e t o an e l e c t r o s t a t i c e f f e c t w h i c h a d j u s t s t h e atmosphere a g a i n s y m m e t r i c a l l y about t h e i o n . I f an i o n i s moving s t e a d i l y , t he i o n atmosphere w i l l be under the i n f l u e n c e o f a permanent d i s t o r t i o n , t h e r e b y d e c r e a s i n g t h e i o n v e l o c i t y . I t was proposed by Wien t h a t under h i g h e l e c t r i c f i e l d s the i o n s move w i t h v e l o c i t i e s so g r e a t as t o p r e v e n t t h e f o r m a t i o n o f an i o n atmosphere; o r i f the i o n i c clo»ud i s p a r t i a l l y formed, the i o n would be removed f r o m i t s - 5 -r e s t r a i n i n g e f f e c t s . The d e v i a t i o n f rom Ohm's l a w i n s t r o n g e l e c t r o l y t e s a t f i e l d s o f about 200,000 v o l t s p e r c e n t i m e t e r was found t o be about 4 p e r c e n t . I n a few i n s t a n c e s however, a much l a r g e r f i e l d e f f e c t was found i n weak e l e c t r o l y t e s t h a n i s p r e s e n t i n s t r o n g e l e c t r o l y t e s , namely about 5 p e r c e n t f o r f i e l d s o f o n l y 120,000 v o l t s p e r c e n t i m e t e r . T h i s e x c e p t i o n a l i n c r e a s e a t r e l a t i v e l y low e l e c t r i c f i e l d s seems t o i n d i c a t e a temporary r i s e i n d i s s o c i a t i o n , an e x p l a n a t i o n w h i c h can be t e n t a t i v e l y adopted. -One. o f t h e few substances, i n v e s t i g a t e d by Wien and S h i e l e (4) was g l y c i n e i n an aqueous s o l u t i o n w h i c h showed an i n c r e a s e o f about 6 p e r c e n t i n a f i e l d o f 1J?0,000 v o l t s p e r c e n t i m e t e r . T h i s s u b s t a n c e i s an amino a c i d , a m p h o l y t i c i n n a t u r e , and o f g r e a t b i o l o g i c a l i m p o r t a n c e , and t h e r e f o r e the l a r g e Wien e f f e c t o f g l y c i n e w a r r a n t s s p e c i a l a t t e n t i o n . 3 . Amino A c i d s The a l i p h a t i c amino a c i d s i n w a t e r e x i s t a l m o s t e n t i r e l y i n a d i p o l a r form. C o n s i d e r f o r example g l y c i n e whose uncharged m o l e c u l e may be w r i t t e n as H^N.CH^.C00H . I n s o l u t i o n t h e r e may be an i n t e r c h a n g e o f a p r o t o n between t h e c a r b o x y l and amino group, r e s u l t i n g i n a d i p o l a r i o n w r i t t e n as+H_N.C"H_.C00~ . I n s t r o n g l y a c i d s o l u t i o n s , a l l amino a c i d s a r e - 4 -p o s i t i v e l y c h a r g e d and m i g r a t e as c a t i o n s i n an e l e c t r i c f i e l d , w h i l e i n s t r o n g l y a l k a l i n e s o l u t i o n s , a l l a r e n e g a t i v e l y c h a r g e d and m i g r a t e as a n i o n s . F o r any amino a c i d t h e r e e x i s t s an i n t e r m e d i a t e pH v a l u e known as t h e i s o e l e c t r i c p o i n t where i t s m o l e c u l e s e x i s t as d i p o l e s , each h a v i n g a n e t charge o f z e r o . F o r most o f the'amino a c i d s , e s p e c i a l l y the s i m p l e ones such as g l y c i n e , the i s o e l e c t r i c p o i n t i s i n f a c t a b road zone o f pH v a l u e s i n w h i c h the ampholyte i s isoelectric S o l u t i o n s o f amino a c i d s i n d i s t i l l e d w a t e r a r e f o r t h e most p a r t i s o e l e c t r i c , e x i s t i n g m a i n l y as d i p o l a r i o n s o r uncharged m o l e c u l e s , t h e l a t t e r b e i n g p r e s e n t i n a n e g l i g i b l e amount. However even a t t h e i s o e l e c t r i c p o i n t t h e r e a r e a p p r e c i a b l e numbers o f a n i o n s and c a t i o n s w h i c h g i v e r i s e t o c o n d u c t i o n . 0. B l u h (j?) has p o i n t e d out t h a t the r e l a t i v e l y l a r g e d e c r e a s e i n r e s i s t a n c e o f g l y c i n e s o l u t i o n s e o u l d be r e l a t e d t o the d i p o l a r p r o p e r t i e s o f t h e s e m o l e c u l e s i n s o l u t i o n , and s u ggested t h a t m o l e c u l e s w i t h s i m i l a r d i p o l a r p r o p e r t i e s s h o u l d show s i m i l a r h i g h e f f e c t s . He s u g g e s t e d t h a t t h e Wien e f f e c t found c o u l d be due t o a temporary s e p a r a t i o n o f the p r o t o n from t h e m o l e c u l e , and t h a t f o r m o l e c u l e s o f s u b s t a n c e s such as p o l y p e p t i d e s whose d i p o l e s e p a r a t i o n i s l a r g e , t h e d i s s o c i a t i o n would be g r e a t e r and the Wien e f f e c t more pronounced. E x p e r i m e n t s i n t h i s d i r e c t i o n , s u g g e s t e d by B l u h t o Wien, c o u l d not be e x e c u t e d ; and the p r e s e n t i n v e s t i g a t i o n has been mm ^ met u n d e r t a k e n w i t h the v i e w o f making p r e l i m i n a r y e x p e r i m e n t s an a number o f amino a c i d s o l u t i o n s and b i o l o g i c a l f l u i d s c o n t a i n i n g t h e s e s u b s t a n c e s . The r e s u l t s b ear out t h e f a c t t h a t most o f the amino a c i d s e t c . show a r e l a t i v e l y s t r o n g Wien e f f e c t , i n agreement w i t h what was e x p e c t e d . Whether the i n c r e a s e i n conductance i s due t o a d i s s o c i a t i o n e f f e c t needs f u r t h e r i n v e s t i g a t i o n . I I . APPARATUS 1. P u l s e G e n e r a t o r The v o l t a g e p u l s e s d e l i v e r e d t o the c o n d u c t i v i t y c e l l a r e g e n e r a t e d f r o m s i n e waves produced by a v a r i a b l e f r e q u e n c y a u d i o o s c i l l a t o r . ( c o m p a r e f i g s . 1 and 2) These s i n e waves a r e a m p l i f i e d by a s i n g l e pentode s t a g e , c l i p p e d and squared by a second pentode a m p l i f i e r , and t h e n d i f f e r e n t i a t e d . The r e s u l t i n g p o s i t i v e and n e g a t i v e p u l s e s are f e d t o a double t r i o d e a c t i n g as a K i p p r e l a y w h i c h i s b i a s e d t o respond o n l y t o the p o s i t i v e i n c o m i n g p u l s e s . A t t h i s s t age the o u t p u t i s a square p u l s e whose d u r a t i o n can be v a r i e d o v e r a wide range by adjustment o f a v a r i a b l e r e s i s t a n c e c o n t r o l l i n g t h e time c o n s t a n t . The p u l s e s from the K i p p r e l a y a r e c o u p l e d t o the cathode o f a beam t e t r o d e m o d u l a t o r s t a g e by means o f a n o t h e r beam t e t r o d e cathode f o l l o w e r . - 6 -l«Ver*«cr T J Mott. V V $T*_.\^V\"V"ev*r •v V S^j "WAV i l l JU1TL ft —.\\o A F i g . l B l o c k ; D i a g r a m o f A p p a r a t u s - 7 -F i g . 2 P u l s e G e n e r a t o r C i r c u i t - 8 -The m o d u l a t i n g s a w - t o o t h wave i s g e n e r a t e d .by a gas t r i o d e o p e r a t i n g i n c o n j u n c t i o n w i t h a t r i o d e cathode f o l l o w e r w h i c h performs the double f u n c t i o n o f c o n t r o l l i n g the l i n e a r i t y o f t h e saw - t o o t h by a fee d - b a c k c o n t r o l o f the anode l o a d o f the gas t r i o d e , and o f p r o v i d i n g a low impedance, n o n - d i s t o r t i n g o u t p u t c o u p l i n g s t a g e o f the mo d u l a t o r g r i d c i r c u i t . The m o d u l a t o r t h u s has p u l s e s from the K i p p r e l a y a p p l i e d ' t o i t s cathode c i r c u i t , and a saw-tooth wave a p p l i e d t o i t s g r i d . The o u t p u t a t the p l a t e i s a s e r i e s o f p o s i t i v e p u l s e s h a v i n g l i n e a r s a w - t o o t h m o d u l a t i o n . The s a w - t o o t h wave a l s o p r o v i d e s the h o r i z o n t a l sweep f o r the cathode r a y o s c i l l o s c o p e . A f t e r d i f f e r e n t i a t i o n t o remove the m o d u l a t i n g s i g n a l , the modulated p u l s e s a r e a m p l i f i e d i n t h r e e more s t a g e s . The f i r s t i s a beam t e t r o d e w i t h cathode d e g e n e r a t i o n , w h i c h s u p p l i e s n e g a t i v e p u l s e s t o the f o l l o w i n g s t r a i g h t t e t r o d e a m p l i f i e r s t a g e whose g r i d i s b i a s e d t o p r e v e n t g r i d c u r r e n t . The o u t p u t a t t h i s s t a g e has an a m p l i t u d e o f about 250 v o l t s and i s a p p l i e d t o the g r i d o f a power t r i o d e o u t p u t s t a g e whose p l a t e s u p p l y may be v a r i e d f r om 0 t o 10,000 v o l t s . T h i s p l a t e v o l t a g e i s o b t a i n e d f r o m a h i g h v o l t a g e s u p p l y u s i n g a h i g h v o l t a g e step-up t r a n s f o r m e r . The stepped-up v o l t a g e i s r e c t i f i e d and f i l t e r e d , p r o v i d i n g a s t a b l e d i r e c t c u r r e n t v o l t a g e . The f i n a l p u l s e s are brought from the t r i o d e p l a t e through a high voltage coupling condenser to the e l e c t r o l y t i c conductivity c e l l . ( f i g . 1) In order to make the pulses seen on the cathode ray oscilloscope appear l i n e a r l y modulated the pulses on the high voltage side were hunched. This has some advantage f or the observation of the Wien effect and has no effect on the re s u l t s . About 80 percent modulation i s now obtainable, t h i s being on the high voltage side. The pulse generator and a l l i t s components was assembled i n a s t e e l rack mounted on casters, ( f i g . 3) 2. Conductivity C e l l A detailed drawing of the c e l l i s shown i n f i g . 4. The c e l l i s constructed from a block of l u c i t e which allows greater ease of construction than glass and yet has comparable i n s u l a t i n g properties. Three holes are d r i l l e d through a block of l u c i t e at ri g h t angles to each other-as shown. Two pieces of glass tubing are f i t t e d into the longitudinal hole and sealed i n place with wax. The l i q u i d to be investigated flows through between the electrodes. The short hole through the c e l l thickness allows the electrodes to be viewed with a t r a v e l l i n g microscope with which the gap between the electrodes may be measured. Thin l u c i t e windows are sealed on with g l a c i a l acetic acid. The hole for the electrodes was d r i l l e d very accurately i n order to keep the Fig.J> A p p a r a t u s F i g . 4 C o n d u c t i v i t y C e l l - 12 -CeV\ vo' o.oo<5 ~ 5 KV. 4=0 ten « lO tAc«^. VT.MH]-Seri«.4 A V Fig.5 C i r c u i t o f V o l t a g e M e a s u r i n g D e v i c e - 1 3 -e l e c t r o d e s d i r e c t l y i n l i n e w i t h each o t h e r a t a l l t i m e s . The e l e c t r o d e s c o n s i s t o f s m a l l p l a t i n u m r o d s s o l d e r e d t o b r a s s r o d s . The f a c e s o f the p l a t i n u m p o r t i o n s were a c c u r a t e l y machined t o i n s u r e e q u a l s p a c i n g o f the e l e c t r o d e gap. Tap h o l e s and screws are p r o v i d e d t o enable the l e a d s t o be a t t a c h e d . The e l e c t r o d e s a r e machined t o f i t t i g h t l y i n t o the c e l l h o l e and a r e h e l d i n p l a c e by means o f two screws. Wax , s e a l s a r e used t o p r e v e n t the f o r m a t i o n o f a i r b u b b l e s i n the c e l l . 3 . V o l t a g e M e a s u r i n g D e v i c e A r e c t i f y i n g c i r c u i t u s i n g a condenser i n p u t i s used t o measure the peak v o l t a g e a c r o s s t h e c e l l . ( f i g . 5 ) . The p u l s e s f e d t o the c e l l a r e r e c t i f i e d and the condenser charged t o the peak v o l t a g e b e i n g m a i n t a i n e d a c r o s s the c e l l . T h i s peak v o l t a g e i s measured a c r o s s a h i g h r e s i s t a n c e a c r o s s the condenser by means o f a vacuum tube v o l t m e t e r . The v o l t a g e s were checked w i t h an e l e c t r o s t a t i c v o l t m e t e r . The v o l t a g e s o b t a i n e d a r e a c c u r a t e t o about 10 p e r c e n t . 4 . P h o t o g r a p h i c R e c o r d i n g The r e c o r d i n g o f the p u l s e t r a c e s was done w i t h the h e l p o f a cathode r a y o s c i l l o s c o p e ( S y l v a n i a type 132) w i t h a 7 i n c h s c r e e n . The o s c i l l o s c o p e was p l a c e d om a s p e c i a l t a b l e , w i t h a b l a c k - o u t c u r t a i n s u r r o u n d i n g i t i n o r d e r t o enable -14 -photographs t o be t a k e n d u r i n g t h e day t i m e . The photographs were t a k e n w i t h a-Duo 35 m i l l i m e t e r U n i v e x camera u s i n g Koddc su p e r x x f i l m . E x p o s u r e s o f 15 seconds were made a t a d i s t a n c e o f 10 i n c h e s and a p e r t u r e f 3 . 5 . • I I I . EXPERIMENTAL PROCEDURE 1. S o l u t i o n s The s o l u t i o n s were p r e p a r e d w i t h d i s t i l l e d w a t e r h a v i n g n e g l i g i b l e c o n d u c t i v i t y f o r t h e measurement i n q u e s t i o n . V a r i o u s s o l u t i o n s o f e q u a l conductance were made, t h e o r d i n a r y ( l o w f i e l d ) conductance b e i n g measured i n a s m a l l c o n d u c t i v i t y c e l l u s i n g a s i m p l e Wheatstone b r i d g e arrangement. S i n c e t a b l e s g i v i n g c o n c e n t r a t i o n s and c o r r e s p o n d i n g conductances o f t h e e l e c t r o l y t e s used were n o t a v a i l a b l e , s o l u t i o n s o f e q u i v a l e n t conductances were p r e p a r e d e m p i r i c a l l y . The m a j o r i t y o f t h e measurements were made on s o l u t i o n s h a v i n g t h e same conductances i n o r d e r t o m a i n t a i n e q u a l o u t p u t l o a d c o n d i t i o n s on t h e p u l s e g e n e r a t o r . To p r e v e n t h e a t i n g o f the s o l u t i o n i t was a l l o w e d t o f l o w t h r o u g h the c e l l a t a r a t e o f about 250 c u b i c c e n t i m e t e r s p e r m i n u t e . A g r a v i t y f l o w system was used. F o r the same r e a s o n the p u l s e s were made t o l a s t f o r v e r y s h o r t t i m e s , and the r a t e o f p u l s a t i o n k e p t l o w . A f r e q u e n c y o f p u l s a t i o n o f 2,000 c y c l e s p e r second was found t o g i v e a s a t i s f a c t o r y - 1 5 -number o f p u l s e s on t h e o s c i l l o s c o p e s c r e e n w i t h o u t p r o d u c i n g e x c e s s i v e h e a t i n g . The l e n g t h o f a s i n g l e p u l s e was about 50 m i c r o s e c o n d s . The i n c r e a s e i n te m p e r a t u r e was found t o be about 1 degree i n a l l c a s e s . 2. E l e c t r i c F i e l d Measurement The f i e l d s t r e n g t h was c a l c u l a t e d as v o l t s p e r c e n t i m e t e r f r om two independent measurements o f v o l t a g e and e l e c t r o d e s e p a r a t i o n . The v o l t a g e was measured by the method d e s c r i b e d i n I I . 3 . w i t h an a c c u r a c y o f 10 p e r c e n t . A t r a v e l l i n g m i c r o s c o p e was used t o measure t h e e l e c t r o d e s e p a r a t i o n t o w i t h i n an e r r o r o f ±.001 m i l l i m e t e r s . S e v e r a l r e a d i n g s were made a l o n g t h e gap and an average t a k e n . Because o f the i n a c c u r a c y o f the v o l t a g e v a l u e s , t h e a c c u r a c y o f the f i e l d s t r e n g t h v a l u e s i s o n l y about 10 p e r c e n t . 3. L i n e a r i t y o f M o d u l a t i o n and F u l s e S l o p e L i n e a r i t y o f the p u l s e m o d u l a t i o n was e s t a b l i s h e d w i t h the h e l p o f c o n d u c t o r s a t l o w e l e c t r i c f i e l d s t r e n g t h s w i t h h i g h v o l t a g e s . I n i t i a l l y , t he c e l l was r e p l a c e d by a w i r e wound 5,000 ohm r e s i s t o r and a peak v o l t a g e o f about 5,000 v o l t s a p p l i e d a c r o s s i t . The t r a c e l i n e a r i t y was o b s e r v e d on the o s c i l l o s c o p e and a d j u s t e d by cha n g i n g the v a r i a b l e r e s i s t o r s A and B shown i n f i g u r e 2. When t h e t r a c e had been made - 16 -as l i n e a r as p o s s i b l e a t the h i g h v o l t a g e s i d e , t h e c o n d u c t i v i t y c e l l was a g a i n i n s e r t e d . The gap between t h e e l e c t r o d e s was made s u f f i c i e n t l y l a r g e t o produce a peak f i e l d a c r o s s the. e l e c t r o l y t e o f about 30,000 v o l t s p e r c e n t i m e t e r . A t t h e s e low f i e l d s t he conductances o f t h e s o l u t i o n s a re i n accordance w i t h Ohm's l a w so t h a t a check on the l i n e a r i t y o f the p u l s e s a p p l i e d t o the c e l l c o u l d a g a i n be made. Bo t h the l o w f i e l d and h i g h f i e l d t r a c e s were r e c o r d e d f o r a l l s o l u t i o n s used. The s l o p e s o f the p u l s e s on the cathode r a y o s c i l l o s c o p e s c r e e n c o u l d be v a r i e d by ch a n g i n g the r e s i s t a n c e i n s e r i e s w i t h the c e l l . T h i s was done whenever the r e s i s t a n c e between the e l e c t r o d e s was a l t e r e d ( t h a t i s when t h e gap was changed) i n o r d e r to m a i n t a i n the s l o p e s a p p r o x i m a t e l y the same and thus e l i m i n a t e any e r r o r t h a t might be due t o the c u r v a t u r e o f the cathode r a y tube. Carbon r e s i s t o r s o f 300 ohms and 80 ohms were used as s e r i e s r e s i s t a n c e s i n the low and h i g h f i e l d measurements r e s p e c t i v e l y . - 17 -I V . RESULTS 1. Method o f I n t e r p r e t a t i o n An attempt was made t o produce a l i n e a r t r a c e on the cathode r a y o s c i l l o s c o p e s c r e e n f o r low e l e c t r i c f i e l d s . Because o f the i m p e r f e c t i o n o f the m o d u l a t i n g s i g n a l a l i n e a r t r a c e c o u l d o n l y be a c h i e v e d w i t h a. s i m u l t a n e o u s d i s t o r t i o n o f the time base. The p u l s e s were bunched a t the h i g h v o l t a g e s , w h i c h has the advantage o f making any Wien e f f e c t more n o t i c e a b l e . Examples o f the l i n e a r i t y o f the t r a c e a t low f i e l d v a l u e s a r e seen i n F i g s . 7 and 8. The s l o p e o f the t r a c e i s c h a r a c t e r i s t i c o f the c o n d u c t i v i t y , as each p u l s e i s modulated w i t h i n c r e a s i n g v o l t a g e and the l e n g t h o f the p u l s e i s p r o p o r t i o n a l t o the conductance o f the s o l u t i o n . F o r h i g h e l e c t r i c f i e l d s the l i n e a r i t y o f the p u l s e s l o p e changes, and the t r a c e t a k e s the f orm seen, f o r example, i n F i g s . 8 and'?. The t r a c e shows a g r e a t e r s l o p e a t t h e h i g h v o l t a g e end, i n d i c a t i n g a Wien e f f e c t . Whether the s l o p e o f the p u l s e s i s c o n t i n u o u s l y changing, o r whether i t can b e . c o n s i d e r e d t o show an a b r u p t change cannot be s a f e l y d e c i d e d w i t h the m a t e r i a l a v a i l a b l e a t p r e s e n t . I n o r d e r t o o b t a i n a p p r o x i m a t e l y the p e r c e n t i n c r e a s e i n conductance due t o the Wien e f f e c t s the f o l l o w i n g p r o c e d u r e was a p p l i e d . Two t a n g e n t s were drawn t o the t r a c e , one i n the - 18 -l o w f i e l d p a r t o f the t r a c e , and a n o t h e r a t t h e s t e e p end o f the h i g h f i e l d s i d e o f the t r a c e . A comparison o f the s l o p e s o f the two t a n g e n t s a l l o w s the c o m p u t a t i o n o f the p e r c e n t i n c r e a s e i n conductance, and p e r m i t s f u r t h e r the c a l c u l a t i o n o f the h i g h f i e l d conductance i f the low f i e l d c o nductance, > as measured by the Wheatstone b r i d g e , i s a c c e p t e d . I t w ould appear t h a t i t i s n e c e s s a r y t o c o r r e c t the s l o p e o f the c u r v e f o r the b u n c h i n g o f the p u l s e s j but i t can be shown t h a t the r a t i o o f the s l o p e s f o r the u n c o r r e c t e d c u r v e s i s the same as the r a t i o o f the s l o p e s f o r the c o r r e c t e d c u r v e s . The c o r r e c t i o n would t a k e the f o l l o w i n g form. ( F i g . 6 ) S i n c e 3 p u l s e s i n the l i n e a r low f i e l d range t a k e p l a c e i n the d i s t a n c e x, t h e n 3 p u l s e s i n the h i g h f i e l d n o n - l i n e a r range must a l s o t a k e p l a c e i n the d i s t a n c e x. To c o r r e c t the low f i e l d s l o p e aA (m, ), the p o i n t A must be moved t o A' g i v i n g t h e s l o p e aA^ ; s i m i l a r l y the h i g h f i e l d s l o p e bB (m^ .) becomes bB*. However i t can be seen t h a t the r a t i o o f these two new s l o p e s i s the same as t h a t o f m,and m_. 2 . R e s u l t s o f Measurements The p e r c e n t i n c r e a s e i n conductance was c a l c u l a t e d f o r a few t y p i c a l s u b s t a n c e s , and the r e s u l t s compared w i t h those o b t a i n e d by Wien are g i v e n i n the f o l l o w i n g t a b l e . The h i g h f i e l d conductance t r a c e s o f a number o f o t h e r s u b s t a n c e s have been o b s e r v e d , and t h e photographs shown i n F i g s . 1 1 , 1 2 , 1 6 , 1 7 , - 19 -Of P u l s e Bunching. - 20 -21, and 23> i n d i c a t e i n g e n e r a l the e x i s t e n c e o f the Wien e f f e c t i n a l l c a s e s . The p e r c e n t i n c r e a s e s have not been e v a l u a t e d i n t h e s e s u b s t a n c e s , but i t can be seen t h a t they are o f the same o r d e r as those f o r the s u b s t a n c e s g i v e n i n the t a b l e . Substance Percent I n c r e a s e i n Conductance a t 180 KV./cm. Own Wien Barium F e r r o c y a n i d e Barium F e r r i c y a n i d e L i t h i u m Bromide H y d r o c h l o r i c A c i d A c e t i c A c i d 24.1 20.4 21.8 10.0 24.4 12.8 (3) 8.8 (3) 14.0 (4) 3.0 (4) 8.0 (4) G l y c i n e V a l i n e G l u t a m i c A c i d B a c t o Tryptone P r o t e o s e Peptone 32.0 30.2 29.9 38.8 . 35.6 6.0 (4) l The p e r c e n t i n c r e a s e s o b s e r v e d a r e i n a l l cases h i g h e r t h a n t h o s e o b t a i n e d by Wien, but r e l a t i v e l y they, are:'in good agreement. Wien c l a i m s a h i g h a c c u r a c y f o r h i s o b s e r v a t i o n s , but he g i v e s v e r y l i t t l e i n f o r m a t i o n about h i s e x p e r i m e n t a l arrangement and w o r k i n g method. On the o t h e r hand t h i s a p p a r a t u s has been d e v e l o p e d w i t h the v i e w o f e s t a b l i s h i n g - 2 1 the e x i s t e n c e o f the Wien e f f e c t f o r a g r e a t range o f s u b s t a n c e s r a t h e r t h a n t o a l l o w the measurement o f conductances i n h i g h e l e c t r i c f i e l d s w i t h a g r e a t degree o f a c c u r a c y . H y d r o c h l o r i c a c i d , whose i n c r e a s e i s due e n t i r e l y t o an i o n i c e f f e c t , shows, the l e a s t Wien e f f e c t , w h i l e weaker e l e c t r o l y t e s s uch as l i t h u i m bromide show a much g r e a t e r i n c r e a s e . The conductances o f the s o l u t i o n s used were i n a l l c a s e s g r e a t e r t h a n those used by Wien, but t h i s , a l t h o u g h p a r t i a l l y e x p l a i n i n g the h i g h e r v a l u e s , " i s not s u f f i c i e n t t o account f o r the l a r g e d i f f e r e n c e s o b t a i n e d between the o b s e r v a t i o n s . The r e s u l t s o f the amino a c i d s and r e l a t e d s u b s t a n c e s are i n good agreement w i t h the h i g h i n c r e a s e s t h a t were e x p e c t e d . A g a i n , the a b s o l u t e v a l u e s computed from the photographed t r a c e s a r e c o n s i d e r e d t o be o f r e l a t i v e v a l u e o n l y , and a r e r e p o r t e d t e n t a t i v e l y . The p e r c e n t i n c r e a s e o b t a i n e d f o r g l y c i n e d e v i a t e s c o n s i d e r a b l y f rom Wien's r e s u l t ; however, the same o r d e r o f p e r c e n t i n c r e a s e i s a l s o o b t a i n e d f o r the o t h e r amino a c i d s measured, v a l i n e and g l u t a m i c a c i d ( F i g s . l 8 and 19). T h i s agreement among the amino a c i d s measured can be e x p e c t e d s i n c e i n a l l c ases the d i p o l e l e n g t h i s the same. P o l y p e p t i d e s , w h i c h c o n s i s t o f s e v e r a l amino a c i d m o l e c u l e s l i n k e d t o g e t h e r , have much g r e a t e r d i p o l e l e n g t h s and i t c o u l d be e x p e c t e d t h a t t h e y w i l l show a g r e a t e r Wien e f f e c t . However, s i n c e p o l y p e p t i d e s were n o t a v a i l a b l e , peptones w h i c h are known t o - 22 -be mixtures of amino aoids and polypeptides, were investigated. The expected large increase i n conductance shows up very we l l i n the peptones used.(Figs.2 0 , 2 1 , and 2 2 ) . A solution of serum, which also contains a mixture of amino acids and polypeptides, shows a very remarkable Wien e f f e c t . ( F i g . 2 3 ) . I t should be noticed that with the peptones and serum the Wien effect appears at r e l a t i v e l y low e l e c t r i c f i e l d s . Fig.7 5 , 0 0 0 Ohm Resistor 30 KV./cm. 180 KV./cm. Fig.8 Barium Ferrocyanide 30 KV./om. 180 KY./cm. Fig. 9 Barium F e r r i c y a n i d e 30 KY./cm. 180 KY./cm. F i g . 1 0 L i t h i u m Bromide 30 KY./cm. 180 KY./cm. F i g . 1 1 Magnesium S u l p h a t e - 24 -30 KV./cm. 180 XV./cm. Fig.12 P o t a s s i u m I o d i d e 30 KV./cm. 180 KV./cm. Fig.13 H y d r o c h l o r i c A c i d 30 10/./cm. 180 KV./cm. F i g . 1 4 A c e t i c A c i d - 25 -Fig.15 G l y c i n e 30 KV./cm. 180 KV./cm. F i g . l 6 ot" A l a n i n e 30 KV./cm. 180 KV./cm. F i g . 17 ^ i l l a n i n e - 26 -30 KV./cm. 180 KV./cm. Fig.18 V a l i n e 30 KV./cm. 180 KV./cm. Fig.19 G l u t a m i c A c i d 30 KV./cm. 180 KV./cm. Fig.20 P r o t e o s e Peptone - 27 -3 0 KV./cm. 1 8 0 KV./cm. Fig.21 Bacto Peptone 3 0 KV./cm. 1 8 0 KV./cm. F i g . 2 2 Bacto Tryptone 4 3 0 KV./cm. 1 8 0 KV./cm. F i g . 2 3 Serum - 2 8 -3. D i s c u s s i o n o f R e s u l t s The r e s u l t s o b t a i n e d i n d i c a t e a. much g r e a t e r i n c r e a s e i n conductance a t h i g h ele<fcric f i e l d s w i t h ampholytes t h a n i s p r e s e n t w i t h s t r o n g e l e c t r o l y t e s . S i n c e s t r o n g e l e c t r o l y t e s a r e a l m o s t c o m p l e t e l y d i s s o c i a t e d i n s o l u t i o n , any Wien e f f e c t o b s e r v e d w i t h them must be due t o an i n c r e a s e d i o n m o b i l i t y , r e s u l t i n g from the d e s t r u c t i o n o f the i o n atmosphere. I n the case o f weak e l e c t r o l y t e s and ampholytes such as amino a c i d s , whose s o l u t i o n s c o n t a i n d i p o l a r i o n s , the Wien e f f e c t must be due to some o t h e r e f f e c t . The Wien e f f e c t i n weak e l e c t r o l y t e s , where a c e r t a i n amount o f u n d i s s o c i a t e d m o l e c u l e s a r e p r e s e n t , i s c o n s i d e r e d t o be due t o a d i s s o c i a t i o n o f t h e s e m o l e c u l e s , r e s u l t i n g i n an i n c r e a s e i n t h e number o f i o n s c a r r y i n g the c u r r e n t . T h i s e f f e c t has not been s t u d i e d v e r y e x t e n s i v e l y , but i t s i n v e s t i g a t i o n , e s p e c i a l l y i n s o l v e n t s o f low d i e l e c t r i c c o n s t a n t (Bauer 6 ) , i s o f g r e a t i n t e r e s t . A s p e c i a l case o f weak e l e c t r o l y t e s a re t h e amino a c i d s , where a g r e a t p e r c e n t a g e o f the m o l e c u l e s e x i s t i n t h e form o f d i p o l a r i o n s . Under the i n f l u e n c e o f a h i g h e l e c t r i c f i e l d the d i p o l a r i o n may undergo a temporary d i s s o c i a t i o n , as proposed by B l u h ( 5 ) , w i t h the p r o t o n b e i n g s e p a r a t e d from the d i p o l e . The r e s u l t s o b t a i n e d w i t h the peptones seems t o bear out t h i s p r o p o s i t i o n . D i p o l a r i o n s whose d i p o l e l e n g t h i s v e r y g r e a t would be e x p e c t e d t o be more r e a d i l y d i s s o c i a t e d , - 29 -p r o d u c i n g a Wien e f f e c t a t r e l a t i v e l y low e l e c t r i c f i e l d s . There i s a l s o the p o s s i b i l i t y t h a t the i n c r e a s e i n conductance o b s e r v e d i s due. t o a d i e l e c t r i c e f f e c t . Amino a c i d s , p o l y p e p t i d e s and peptones a r e a l l known t o have h i g h d i e l e c t r i c c o n s t a n t s , and i n h i g h e l e c t r i c f i e l d s t h e r e may be an i n c r e a s e i n the d i p o l e l e n g t h r e s u l t i n g i n an i n c r e a s e i n the p o l a r i z a t i o n . T h i s c o u l d l e a d t o a c o n s i d e r a b l e p o l a r i z a t i o n c u r r e n t b e s i d e s the c o n d u c t i o n c u r r e n t . Some t h e o r e t i c a l c o n s i d e r a t i o n s about the Wien e f f e c t have been made by B l u m e n t r i t t (7,8), Falkenhagen (9), and by Onsager (10). The f i r s t mentioned papers t r e a t the Wien e f f e c t i n s t r o n g e l e c t r o l y t e s o n l y . Onsager's paper a t t e m p t s t o c a l c u l a t e the e f f e c t o f an e x t e r n a l e l e c t r i c f i e l d on the e l e c t r o l y t i c d i s s o c i a t i o n o f weak e l e c t r o l y t e s , and i n some p a r t s compares h i s r e s u l t s q u a n t i t a t i v e l y w i t h Wien's r e s u l t s . However,no c o n s i d e r a t i o n i s g i v e n t o the p a r t i c u l a r l y g r e a t i n c r e a s e o b s e r v e d by Wien i n g l y c i n e s o l u t i o n , w h i c h a p p a r e n t l y b e l o n g s t o a s p e c i a l c a s e . The t r a c e s o b t a i n e d a t f i r s t s i g h t appear t o be p a r a b o l i c , and i f t hey were o f t h i s shape, the r a t e o f change o f the curv e w i t h r e s p e c t t o the f i e l d s t r e n g t h , w h i c h i s e q u a l t o the c o n d u c t i v i t y , s h o u l d be l i n e a r . That i s = aE where A X i s the i n c r e a s e i n conductance, E the f i e l d s t r e n g t h , - 30 -and a i s a c o n s t a n t . However, on c l o s e r i n s p e c t i o n o f the t r a c e s i t can be seen t h a t the r a t e o f i n c r e a s e i s l e s s t h a n q u a d r a t i c , w h i c h means t h a t the i n c r e a s e i n conductance i s l e s s and c o u l d be r e p r e s e n t e d by A X = aE*- - bE* where b i s a n o t h e r c o n s t a n t . A s i m i l a r e x p r e s s i o n has been used by B l u m e n t r i t t (8) who, f o r o r d i n a r y s t r o n g e l e c t r o l y t e s , i s a b l e t o d e r i v e the c o n s t a n t s a and b t h e o r e t i c a l l y f r om t h e i r dependency on the v a l e n c i e s o f t h e i o n s p r e s e n t , the c o n c e n t r a t i o n , and the d i e l e c t r i c c o n s t a n t o f the s o l u t i o n . A t h e o r e t i c a l e x p l a n a t i o n f o r t h e ampholytes would have t o develop' a s i m i l a r f o r m u l a on the b a s i s o f the knowledge o f the d i p o l a r s t r u c t u r e o f the m o l e c u l e s i n t h e s e s o l u t i o n s . V. CONCLUSIONS The o b j e c t o f t h i s i n v e s t i g a t i o n has been the developement o f an a p p a r a t u s t o observe i n a d i r e c t way the f u n c t i o n a l c o n n e c t i o n between the f i e l d s t r e n g t h and the conductance o f ampholytes. I t was shown c o n c l u s i v e l y t h a t amino a c i d s e x h i b i t the p r o p e r t i e s o f the Wien e f f e c t t o a l a r g e degree. Whether the e f f e c t i n these s u b s t a n c e s i s due e n t i r e l y t o a s e p a r a t i o n e f f e c t , as o r i g i n a l l y s u r m i s e d by 0 . B l u h (5), must be t h e o b j e c t o f f u r t h e r i n v e s t i g a t i o n . The work e n v i s a g e d w i l l have t o pr o c e e d i n two d i r e c t i o n s . - 31 -1. A i i i n v e s t i g a t i o n o f a g r e a t e r number o f amino a c i d s and p a r t i c u l a r l y o f p o l y p e p t i d e s , w i l l have t o be made i n o r d e r t o show a c o n n e c t i o n between increase," i n conductance and the d i p o l e l e n g t h . Due c o n s i d e r a t i o n must be g i v e n t o the e f f e c t o f c o n c e n t r a t i o n , and o f the pH o f the s o l u t i o n s . 2. A d i s s o c i a t i o n e f f e c t , as d i s t i n g u i s h e d from a p o l a r i z a t i o n e f f e c t , s h o u l d show a time l a g , w h i c h c o u l d be d e t e c t e d by m o d u l a t i n g the p u l s e s a p p l i e d t o the' ampholyte I n the o p p o s i t e d i r e c t i o n t o t h a t a t p r e s e n t , namely from h i g h t o low f i e l d s . F u r t h e r improvements i n the a p p a r a t u s w i l l have to p r o v i d e an e x t r e m e l y l i n e a r m o d u l a t i n g s i g n a l , and f o r an a c c u r a t e c o n t r o l o f t h e p u l s e d u r a t i o n . The p u l s e g e n e r a t o r can n a t u r a l l y a l s o be used as a g e n e r a t o r f o r a b r i d g e system, so t h a t more a c c u r a t e r e s u l t s t h a n are o b t a i n a b l e w i t h the cathode r a y t r a c e w i l l be \ p o s s i b l e . The a p p a r a t u s can a l s o be used f o r the measurement o f h i g h f i e l d conductance i n s o l i d e l e c t r o l y t e s , and to f i n d the break-down p o t e n t i a l s o f s o l i d and l i q u i d i n s u l a t o r s . However, the i n v e s t i g a t i o n o f amino a c i d s and s u b s t a n c e s o f a s i m i l a r n a t u r e w i l l remain i n the c e n t r e o f i n t e r e s t because o f the r e s u l t s o b t a i n e d . I t can o n l y be b r i e f l y remarked t h a t the s e p a r a t i o n o r d i s s o c i a t i o n e f f e c t o f amino a c i d s , p o l y p e p t i d e s , and p r o t e i n s i n h i g h e l e c t r i c f i e l d s would a l l o w the assumption t h a t such - 32 -s e p a r a t i o n s a r e t a k i n g p l a c e i n the l i v i n g t i s s u e . I t i s w e l l e s t a b l i s h e d t h a t i n t i s s u e , membrane p o t e n t i a l s o f the o r d e r o f 0.1 v o l t e x i s t . C o n s i d e r i n g the t h i c k n e s s o f the e l e c t r i c a l d ouble l a y e r t o be o f the o r d e r o f 10 c e n t i m e t e r s , we see t h a t we a r e d e a l i n g w i t h e l e c t r i c f i e l d s o f the o r d e r o f 10 v o l t s per c e n t i m e t e r , the same o r d e r w h i c h we were a b l e t o o b t a i n i n o u r e x p e r i m e n t s . The d i f f u s i o n o f amino a c i d s e t c . i n t o the e l e c t r i c a l double l a y e r space s h o u l d r e s u l t i n the d i s s o c i a t i o n o f the d i p o l e s . Through such a d i s s o c i a t i o n o f the p r o t o n from the amino a c i d d i p o l e , t h e r e s t m o l e c u l e becomes a n e g a t i v e i o n . E l e c t r o p h o r e s i s , b e s i d e s d i f f u s i o n , becomes p o s s i b l e , and can e f f e c t i v e l y produce the t r a n s p o r t o f amino a c i d m o l e c u l e s i n one d i r e c t i o n . I t may w e l l be t h a t t h i s e x p l a n a t i o n has some b e a r i n g on the problem o f b i o l o g i c a l p e r m e a b i l i t y . - 33 -BIBLIOGRAPHY 1. M. Wien, A n n a l e n d e r P h y s i k 83, 327, 1927. 2. M. Wien, A n n a l e n d e r P h y s i k 83, 793, 1928. 3. M. Wien, A n n a l e n der P h y s i k (3)1, 4 0 0 , 1929. 4. M. Wien, P h y s i k a l i s c h e Z e i t s c h r i f t 32, 545, 1931. 3. 0 . B l u h , P r o t o p l a s m a Bd. X X I I I H e f t 3, 4 1 0 , 1935. 6. F. Bauer, A n n a l e n d e r P h y s i k (5)6, 253, 1930. 7. M. B l u m e n t r i t t , A n n a l e n d e r P h y s i k 85, 812, 1928. 8. M. B l u m e n t r i t t , A n n a l e n d e r P h y s i k (5)1, 195, 1929. 9. H. F a l k e n h a g e n , P h y s i k a l i s c h e Z e i t s c h r i f t 32, 353, 1931. 10. L. Onsager, J o u r n a l o f C h e m i c a l P h y s i c s 2, 599, 1934. 

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