Direct photometric detection of inorganic anions by capillary zone electrophoresis using stacking effect of sulfate ion on sample ions

Abstract

Stacking effect of sulfate ion on the analysis of inorganic anions by capillary zone electrophoresis was examined during the sample injection period. A used silica capillary was dynamically coated with tetradecyltrimethylammonium bromide (TDTMA+Br-) to control the electroosmotic flow. Analyte anions were directly detected by photometry at 214 nm. Five kinds of anions, namely bromide, nitrite, nitrate, molybdate, and tungstate, were detected. Anion separation was developed using 4×10-3 M sodium sulfate in the carrier solution. Peak heights for anions increased along with additional Na2SO4. The stacking effect was more effective for the anions with high mobility than those with low mobility. Calibration graphs for nitrate and nitrite showed good linearity in the concentration range of 10-6 to 10-5 M.