Feasibility of using capillary zone electrophoresis with photometric detection for the trace level detection of bromate in drinking water

The feasibility of applying a capillary zone electrophoretic (CZE) method for the trace analysis of bromate, a suspect human carcinogen, in drinking water was studied. Using a bare fused-silica capillary (75 µm inner diameter) coupled with indirect ultraviolet detection (200 nm), 0.25 mM cetyltrimethylammonium bromide, 5% methanol and 5.0 mM phthalate at pH 5.0–5.2, an electrokinetic injection of 15 kV and 10 s, a separation voltage of 18 kV (negative polarity) and a capillary temperature of 15°C, bromate was detected in high purity water at ≤10 µg l−1. The method was applied to three bottled water sources and to local municipal water. If needed, additional sample-handling steps, consisting of an off-line pre-concentration step and pH adjustment to 5.5, was used to improve detection limits (from a high of 400 µg l−1 to ≤10 µg l−1) and baseline noise. Signal-to-noise ratios also increased by adding sodium phosphate (1.1 µg ml−1) to all sources prior to analysis. Although the CZE method was capable of detec...