Advanced Ion Chromatographic Methods for the Determination of Bromate, Bromide, Chlorite, and Perchlorate in Drinking Waters

摘要

The USEPA method 300.0, developed in the early 1980’s,has become the workhorse for the determination of theseven common anions in drinking waters. Since then USEPA has developed three new IC methods for thedeterminations of bromide and the disinfection byproducts, bromate, chlorate, and chlorite, and perchlorate indrinking waters. Per Stage 1 of the Information Collection Rule (ICR), promulgated in 1997, USEPA method 300.1is used to analyze drinking waters for inorganic disinfection byproducts, specifically bromate and chlorite. Themaximum contaminant levels for chlorite and bromate are currently set at 1.0 and 0.01 mg/L, respectively. Bromateis a suspected carcinogen, and in order to lower its quantitation limits, USEPA modified method 300.1 anddeveloped method 317 in which a post-column derivatization reaction specific to bromate is performed. Themethod 317 enables quantitation of bromate at 0.5 μg/L. USEPA expanded the unregulated contaminant monitoringregulation (UCMR) in 1999 to include perchlorate, and method 314.0 is used to determine perchlorate in the rangeof 4 to 100 μg/L.This paper describes running these environmental IC methods on the IC5000 Ion Chromatography System. TheQuikSep columns enable separation of μg/L levels of bromate in the presence of 25 ppm carbonate, 50 ppmchloride, 100 ppm sulfate, and μg/L levels of perchlorate in the presence of 1000 ppm of each of carbonate,chloride, and sulfate. For the methods, 300.1 and 314, chemical suppression is achieved using a MicroSuppressorthat is quickly and reproducibly regenerated while a sample loop is being filled. For the method 317, the postcolumn reaction is employed consisting of pulseless reagent delivery system, efficient mixing and heating of themixed stream and colorimetric detection. The developed methods are sensitive, accurate, and precise fordetermining various pollutants in drinking waters. The quantitation limits range from 0.5 μg/L for bromate to 3.5μg/L for perchlorate.