Simultaneous determination of chloride, sulphate, orthophosphate and organic anions in human urine by capillary isotachophoresis.

The principle of isotachophoresis has been used to develop a simple, specific and sensitive analytical method for the determination of anions in untreated urine. Isotachophoretic separation of anions in the presence of complex-forming counter ions (e.g. Cd2+) enables the quantitative separation and determination of chloride, sulphate and orthophosphate in the same sample and the less accurate measurement of the concentrations of citrate, formate, acetate, hippurate, benzoate and glucuronate. The mean deviation from 100% recovery of chloride, sulphate and orthophosphate added to urine samples is 3.1%. The proposed method shows good agreement with chemical (routine) methods.