SummaryA systematic investigation of operational buffer systems, sample preparation and instrument parameters for achieving the best possible performance for determining an homologous series of N-benzyl-N-alkyl-N,Ndimethylammonium chloride compounds by capillary zone electrophoresis with direct UV detection. The most effective separation was achieved within 3.5 min with the addition of acetonitrile (40 %) in a phosphate buffer (20 mM pH 5.2) using a 40 cm fused-silica capillary operating at 25 KV and 20 ~ Degassing of all electrolyte solutions and samples was very important. The linearity and repeatability for each compound were satisfactory. To improve detection limits, on-column sample preconcentration, sample stacking, was investigated achieving a tenfold enrichment factor and quantitation limits about 10 -7 M.

Trace-level inorganic anions in seawater are separated efficiently by capillary zone electrophoresis using direct UV detection. The carrier electrolyte is 50 mM borate at pH 9.3 and contained 1.5M NaCl. This buffer solution is adopted to prevent interference from high concentrations of the chloride ion in seawater. No electro-osmotic flow reverser is used to shorten the analysis time. The experimental conditions such as the concentration of NaCl in the carrier electrolyte, capillary inner diameter, applied current, and temperature are optimized. Linear plots are obtained in the concentration range of 0.1 to 20 microg/mL. The quantitation limits of the anions are in the order of 0.02 to 0.1 microg/mL. The proposed method may be applicable to the determination of inorganic anions in other environmental samples and effluents of a power plant.

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