AWWA WQTC60699

A method to differentiate total organic chlorine (TOCl), total organic bromine (TOBr)and total organic iodine (TOI), which involves carbon adsorption, pyrolysis and ionchromatographic detection, has been developed by previous researchers and applied tothe analysis of water samples. However, incomplete recoveries from model compoundsand interference from auxiliary gas (CO₂) were reported. The objective of this researchwas to determine the best TOX protocol for use with IC analysis. Two commercialanalyzers (one using a pure O₂ carrier and one using O₂/CO₂ mixture) and threecommercially available activated carbons (two coconut based and one bituminous coalbased) were selected for this research. Chlorine, bromine and iodine containing modelcompounds and chlorinated water samples with varying levels of bromide and iodidewere tested on both analyzers and three activated carbons. Results showed that thepyrolytic analyzer using pure O₂ and off-line IC combined with a standard TOX carbon(coconut based) achieved the most complete recovery of TOCl, TOBr and TOI for bothmodel compounds and real samples. There was no obvious difference between the twoanalyzers when used in microcoulometric detection mode. The O₂/CO₂ pyrolytic systemand off-line IC method showed incomplete recovery for some samples due to thecondensation of halide ions and incomplete transfer line flushing. The use of CO₂ as anauxiliary gas resulted in interference in IC analysis, which made it necessary to purgedissolved CO₂ before IC analysis. The TOX method is moderately sensitive to nitraterinse volume. The monohaloacetic acids were partly washed out during samplepreparation. This problem was solved by modifying the nitrate rinsing solution. Completerecovery was achieved for all the selected compounds by this modified TOX protocol. Includes 13 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/15/2004

Number of Pages:

20

File Size:

1 file , 590 KB