Simultaneous determination of oxalic and citric acids in urine by high-performance liquid chromatography.

A simple method for the simultaneous determination of oxalic and citric acids had been developed using reversed-phase HPLC. An aqueous solution containing potassium dihydrogen phosphate (0.25%) and tetrabutylammonium hydrogen sulphate (2.5 mmol) at pH 2.0 was used as mobile phase. Under these conditions both the components were well resolved and detected at 210 nm. The recovery for oxalic and citric acids was 97% and 102%, respectively. The method presented here was applied to urine specimens of a large number of urolithic patients and control subjects. Because of the simplicity of the method its application provides better means of monitoring the concentration of oxalic and citric acids in the formation of renal calculi.