Determination of haloacetic acids in tap water by capillary electrophoresis with direct UV detection

Application of capillary zone electrophoresis with direct ultraviolet (UV) detection for determining the haloacetic acids in tap water is described. The haloacetic acids were monochloroacetic, trichloroacetic, monobromoacetic, dichloroacetic. bromochloroacetic, and dibromoacetic acids. For direct UV detection, the haloacetic acids were treated by liquid-liquid extraction and concentrated up to 2000 times. The analysis was successful with a fused-silica capillary containing 25 mM phosphate -0.5 mM cetyltrimethyl-ammonium chloride by direct UV detection at 185 nm. This technique can determine haloacetic acids at the 5 mug L-1 level in tap water within 7 min, except for trichloroacetic acid.