Ion analysis by capillary zone electrophoresis with indirect injection: applications in the nuclear power industry

Abstract

Capillary zone electrophoresis (CZE) was used for the determination of trace level inorganic ions and its applicability in the power industry investigated. Detection of Cl^–, SO₄^2– and NO₃^– was accomplished by using a background electrolyte consisting of 7.0 mM CrO₄^2–, 0.5 mM TTAB and 1.0 mM NaHCO₃. To enhance electrokinetic injection, transient isotachophoretic conditions were employed by the addition of 100 µl of 70 mM sodium octanesulfonate to 100 ml of sample. The addition of a 20 µg l^–1 aliquot of tungstate was used as an internal standard to limit possible electrokinetic injection biases. In addition, 150 µm extended path length capillaries were investigated for improving detection limits. Detection limits obtained via CZE were comparable to those given by ion chromatography (IC) with the use of the extended path capillaries. CZE results obtained were 0.38, 0.54 and 0.75 µg l^–1 for Cl^–, SO₄^2– and NO₃^–, respectively, while IC results were 0.10, 0.30 and 0.25 µg l^–1. The advantages of using CZE as opposed to IC for the analysis of inorganic anions in power plant reactor water are discussed.