DETERMINATION OF INORGANIC AND SMALL ORGANIC-ANIONS IN PURE BORIC-ACID USING CAPILLARY ZONE ELECTROPHORESIS

Inorganic and small organic anions were determined in pure boric acid using an on-line process for removal of the boric acid matrix from the capillary by adjusting the pH of the electrolyte and the electroosmotic flow. Employing this procedure, the matrix has no further influence on the separation and the analytes can be detected up to analyte-to-matrix ratios (ATMR) of 1:5 . 10(5) to 1:4 . 10(5) using hydrostatic injection. The limits of detection of the analytes were improved by on-line preconcentration procedures such as electrokinetic injection and sample stacking, resulting in an increased ATMR of 1:1 . 10(7) to 1:3 . 10(7) for sample stacking. These optimized conditions were applied to analyse two different batches of boric acid for impurities.