Analysis of haloacetic acid mixtures by HPLC using an electrochemical detector coated with a surfactant-nafion film

High pressure liquid chromatography (HPLC) using an electrochemical (EC) de tector electrode of pyrolytic graphite coated with a him of ionomer Nafion and the water-insoluble surfactant didodecyldimethylammonium bromide (DDAB) was used to achieve separation and detection of all six bromo- and chloro- acetic acids. The Nafion-DDAB film preconcentrates the acid anions facilita ting their electrochemical detection by direct reduction at - 1.2 V versus SCE. Detection limits were poorer than the EPA-approved GC-ECD method, but HPLC-EC avoids the derivatization necessary for GC. The HPLC-EC method also detected tribromoacetic acid, which has not been determined simultaneously with other halogenated acids by reported chromatographic methods. The HPLC -EC method using a Nafion-DDAB-coated detector electrode gave comparable re sults to GC-ECD for the determination of TCA in drinking water. (C) 1999 El sevier Science B.V. All rights reserved.