Determination of oxalic acid in urine by co-electroosmotic capillary electrophoresis with amperometric detection

Co-electroosmotic capillary electrophoresis with amperometric detection at a Cobalt phthalocyanine (CoPC) modified carbon paste electrode was evaluated for the determination of oxalic acid in urine. The running buffer consisted of 10 mM phosphate (pH=5.70) and 0.25 mM Cetyltrimethylammonium bromide. Under the optimum conditions, a detection limit of 0.12 μM was achieved for oxalic acid. The response was linear between 0.5 and 1000 μM with a correlation coefficient of 0.9995. Applications of the method to real urine samples were described.