Application of capillary electrophoresis for the determination of dissolved gases in water samples: I. Determination of dissolved oxygen

The determination of dissolved oxygen in water samples was performed by capillary electrophoresis. This was based on the oxidation of pyrogallol in alkaline media by dissolved oxygen. The oxygen sample was injected into the capillary electrophoresis system consisting of phosphate buffer at pH 5.6 and 0.5 M pyrogallol. Electrophoretic mixing of sample and reagent was achieved during the electrophoretic run and the reaction product was monitored at 440 nm. The assay procedure was optimized with respect to the carrier electrolyte concentration and pH, pyrogallol concentration, sample pH, and modes of operation of the applied voltage. As little as 20 ppb of the dissolved oxygen could be determined by the proposed method within 10 min. The method was successfully applied for the determination of dissolved oxygen in river and drinking water.