DIRECT PHOTOMETRIC DETECTION OF INORGANIC ANIONS BY CAPILLARY ZONE ELECTROPHORESIS USING STACKING EFFECT OF SULFATE ION ON SAMPLE IONS

Stacking effect of sulfate ion on the analysis of inorganic anions by capillary zone electrophoresis was examined during the sample injectio n period. A used silica capillary was dynamically coated with tetradec yltrimethylammonium bromide (TDTMA(+)Br(-)) to control the electroosmo tic flow. Analyte anions were directly detected by photometry at 214 n m. Five kinds of anions, namely bromide, nitrite, nitrate, molybdate, and tungstate, were detected. Anion separation was developed using 4x1 0(-3) M sodium sulfate in the carrier solution. Peak heights for anion s increased along with additional Na2SO4. The stacking effect was more effective for the anions with high mobility than those with low mobil ity. Calibration graphs for nitrate and nitrite showed good linearity in the concentration range of 10(-6) to 10(-5) M.