Development of an SPE/CE method for analyzing HAAs

Abstract

A method to analyze haloacetic acids (HAAs) in drinking water was developed using a capillary electrophoresis (CE) ion analyzer for analyte separation and detection. The effects of background electrolyte (BGE) composition, sample injection approach, and on- and offcapillary preconcentration techniques on HAA peak resolution and method sensitivity were evaluated. The recommended BGE consists of 25 mM phosphate buffer at pH 5.7 with 1 mM tetradecyltrimethylammonium hydroxide as the electroosmotic flow modifier. Aqueous samples were preconcentrated using solid-phase extraction (SPE) and then loaded onto an extended light path capillary (75-μm inside diameter ÷ 56-cm effective length) using pressure injection (50 mbar for 12 s). The estimated method detection limits were in the range of 1.5–3.5 μg/L. The SPE/CE method was used to analyze ambient and spiked water samples from a water distribution system, and results were in good agreement with those using US Environmental Protection Agency method 552.2. The main advantage of the SPE/CE method over the currently approved HAA analysis methods is that it does not require HAA derivatization, which involves potentially hazardous chemicals and conditions. Disadvantages of the SPE/CE method are that it does not offer a significant time savings (because of the need for off-capillary sample preconcentration) and chlorodibromoacetic acid could not be quantified because of interference from a contaminant peak.