[Rapid determination of creatinine in urine by capillary electrophoresis in a multiple injection mode]

The level of urinary creatinine in clinic diagnosis is one of the useful index of renal function, and is often used as a reference of some biochemical substance determined in random urine. In this paper, a rapid multiple-injection capillary electrophoresis(CE) method for the determination of urinary creatinine is reported. A 36 cm x 50 microns coated capillary, a phosphoric acid buffer(0.1 mol/L, pH 2.5)and UV-detector at 200 nm wavelength were used in this method. In comparing with single injection for five samples, the analysis time of five successive injections can save 20 min. By use of pyridine as internal standard, the correlation between the concentrations of creatinine and the corresponding peak height ratios of creatinine and pyridine is good(r = 0.9996), and the assay precision is acceptable. We also compared the CE method with the bio-analyser(Jeffe' kinetic), and the results showed a satisfactory correlation (r = 0.9773, n = 12) and a shorter analysis time.