Separation of inorganic anions by capillary zone electrophoresis employing sulfonated dyes as probes for indirect UV detection

Abstract

Using indirect photometric detection of anions in capillary zone electrophoresis, the composition of background electrolyte, i.e. buffering system, detection probe and electroosmotic flow velocity should be carefully optimized. In this work, the sulfonated dyes and dye intermediates were tested as the contrast highly absorbing compounds, which are displaced by non-absorbing analytes during the separation and detection. The citrate-based background electrolyte was applied with addition of up to 13 mmol⋅l-1 of dyes. The best separation comparable to the separation of inorganic anions using chromate indirect detection probe was achieved using 1,3,5,7-naphthalene tetrasulfonic acid, which best matches the electrophoretic mobilities of the analyzed inorganic anions.