CHROMATOGRAPHY, Vol. 34 (2013), No. 2, pp. -89

A rapid analytical method for inorganic anions has been developed using a laboratory-built CE system. The miniaturized CE system was constructed from a 10 cm uncoated fused-silica capillary, sample and electrolyte vials, a power supply instrument, two platinum electrodes, a capacitively coupled contactless conductivity detector (C⁴D), and a cool plate to keep at constant temperature of the C⁴D. Although hydrodynamic and electrokinetic injection techniques have been widely used in CE, we employ a continuous sample introduction method. The procedure is relatively simple and has the advantage that it does not require pressure control and vial exchange, so it is suitable for the miniaturized CE system. Six anions (chloride, sulfate, nitrate, nitrite, fluoride, phosphate) were successfully separated and detected at sub-ppm levels within 80 seconds using a 9 mM histidine (His)/15 mM malic acid aqueous buffer solution (pH 3.6) containing 50 mM N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (DDAPS). The RSD values for six replicate injections of a mixed standard solution were found to be in the ranges of 0.76-2.81% for migration times and 0.77-8.55% for peak areas, respectively. The developed method was applied for the analysis of inorganic anions in tap water, river water, mineral water, orange juice, and vegetable juice. These results indicate that the miniaturized CE-C⁴D system is suitable for the rapid analysis of inorganic anions in various samples.