UBC Undergraduate Research

Halogenated organics identification : qualitative analysis : final report Fong, Derek; Dhaliwal, Tanveer; Song, Sein; Kim, Youni; Kao, Arthur


The overall objective of this Problem Based Laboratory (PBL) project is to use a silver nitrate test to determine if halogens are present in non-halogenated waste samples collected by the Environmental Services Facility (ESF). The silver nitrate test was carried out on 36 out of the 50 non-halogenated samples collected. It was not possible to test all samples because samples appearing to have significant amounts of suspended solids or foreign materials were excluded in order to ensure accurate results. In addition, the Karl Fischer titration apparatus was set up for the subsequent group to complete the water content test. Silver nitrate was used because it reacts with chlorine, bromine and iodine ions in the waste solvent to form precipitates. Nitric acid was then added to each sample so the precipitates not containing halogens are dissolved. From the average mass of the precipitate sample and its duplicate, 11 out of the 36 samples non-halogenated samples contained no precipitate or gave a negative mass reading, 17 out of the 36 samples contained a precipitate mass between 0 g and 0.05 g, and the remaining 8 out of 36 samples contained a precipitate mass greater than 0.05 g. While the results from the test do not give a direct indication to the parts-per-million halogen concentration in each sample, it does show that approximately 61% of the “non-halogenated” samples were in fact halogenated. There is therefore a significant problem with the improper filling of non-halogenated waste containers in laboratories across campus. Because safety during the experiment is of paramount importance, safety inspections were carried out during each laboratory period. Due to the volatile and corrosive nature of many of the chemicals used, all tests were performed under a fume hood with proper protective equipment such as gloves, lab coats, and safety glasses. To dispose correctly of these chemicals, all used samples were disposed of in halogenated waste containers. Disclaimer: “UBC SEEDS provides students with the opportunity to share the findings of their studies, as well as their opinions, conclusions and recommendations with the UBC community. The reader should bear in mind that this is a student project/report and is not an official document of UBC. Furthermore readers should bear in mind that these reports may not reflect the current status of activities at UBC. We urge you to contact the research persons mentioned in a report or the SEEDS Coordinator about the current status of the subject matter of a project/report.”

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