Application of capillary electrophoresis for inorganic selenium speciation in the frame of high-level waste management.

Abstract

Capillary electrophoresis (CE) with direct UV detection is proposed for speciation of inorganic Se in high-level liquid waste. In this aim, the optimal conditions of measurements (pH, electrolyte buffer concentration) and the influence of nitrate excess on the quantitative determination of Se(IV) and Se(VI) were studied. Different electrolyte buffers were considered: carbonate, phosphate and citrate. It was found, that citrate buffer is the most suitable for the application under consideration. Under the chosen optimal conditions (20 mmol L(-1) citrate buffer, pH 2.5), calibration curves for Se(IV) and Se(VI) are linear in the concentration range 10(-4)-10(-3) mol L(-1). The detection limits are 4x10(-6 )for Se(IV) and 2x10(-5) for Se(VI). The accuracy of the procedure was checked by calculating the recovery by spiking simulation solutions. Relative standard deviation (S(r)) is less than 10%.