Application of capillary electrophoresis for determination of organic acids in waste waters

Nine organic (formate, acetate, propionate, butyrate, oxalate, malonate, succinate, phthalate and maleate) and seven inorganic anions (chloride, sulphate, nitrite, nitrate, fluoride, phosphate and carbonate) were separated by capillary electrophoresis using pyridine-2,6-dicarboxylic acid as electrolyte and tetradecyltrimethylammonium bromide as electro-osmotic flow modifier. The analytes were detected by measuring indirect UV-absorption with detection limits of below 0.5 mg/l for all the analytes (except for phthalate 1.0 mg/l). The method was applied for the analysis of waste water samples collected in a dumping area. In addition to butyrate, propionate and succinate, high concentrations of acetate were found. The inorganic anion analysis can be simultaneously performed with the proposed method, since six common inorganic anions (carbonate, chloride, fluoride, nitrate, phosphate and sulphate) were also separated from the analytes and from each other.