Determination of nitrate and nitrite in Hanford defense waste by reverse-polarity capillary zone electrophoresis

Abstract

This paper describes the first application of reverse-polarity capillary zone electrophoresis for rapid and accurate determination of nitrate and nitrite in Hanford defense waste (HDW). The method development was carried out by using synthetic Hanford waste, followed by the analysis of four real HDW samples. Hexamethonium bromide (HMB) was used as an electroosmotic flow modifier in a borate electrolyte at pH 9.2 to decrease the electroosmotic flow, enhancing the speed and resolution of the analytical determination of nitrate and nitrite in high ionic strength HDW samples. The application of this capillary zone electrophoresis method, when compared with ion chromatography for two major components of HDW, nitrate and nitrite, slightly reduced analysis time, eliminated most pre-analysis handling of the highly radioactive sample, and cut analysis wastes by more than two-orders of magnitude. The migration times of nitrate and nitrite in the real HDW and the spiked HDW samples were within a precision of less than 3% relative standard deviation. The selectivity ratio test used for peak confirmation of the spiked samples was within 96% of the real sample. Method reliability was tested by spiking the matrix with 1.0 m M nitrate and nitrite. Recoveries for these spiked samples were 93–103%.