Determination of trace oxalate and citrate in urine with capillary electrophoresis / 中华检验医学杂志

ABSTRACT

Objective To establish a method for determining oxalate and citrate in urine simultaneously by capillary electrophoresis.The components,the concentration and pH of the buffer solution,the separation voltage and the injection time on theseparation were studied in detail.Methods The separations were carried out using potassium dihydrogen phosphatebuffer ina fused-silica capillary tubeby capillary zone electrophoresis (CZE) and the detection were monitored by UV.24 h-urine samples from patients (n =5) and health control (n =5) were collected from Zhongshan Hospital of Fudan University for systematically validating the method developed.Results The optimized separations were carried out using a 50 mmol/L potassium dihydrogen phosphatebuffer solution (pH 6.5) in a fused-silica capillary tube of 50 cm × 50 μm I.D.Injections were made by using the pressure mode for 10 s at 34 mbar.The detections were monitored by a UV at 200 nm after samples were separated at avohage of 30 kV.Under the seconditions,urinary oxalate and citrate were separated completely within 5 min.The relative standard deviations of migration time and peak area within-run foroxalate and citrate were less than 1％ and 3.0％ and the betweenrun relative standard deviations were less than 2.0％ and 4.0％,respectively.The detection limits were 1 mg/L for both oxalate and citrate.The linearity ranges of oxalate and citrate were both 0-500 mg/L with the correlation coefficient between 0.999 5 and 0.995 4 (P ＜ 0.05),respectively.The average recoveries were 102.38％ for oxalate and 92.74％ for citrate.Conclusion This method is proved to be simple,sensitive and accurate,and also applied to determine oxalate and citrate in urine samples with satisfactory results.