[Urine profiling by capillary electrophoresis with online stacking of moving reaction boundary]

Rapid and sensitive profiling of urine holds evident significance for the discovery of new biomarkers and clinical diagnosis. In this study, a simple, rapid and sensitive moving reaction boundary (MRB)-induced stacking technique is described for the analysis of urine profiling by capillary zone electrophoresis (CZE). The MRB was formed with acidic Gly-HCl as the sample buffer and alkaline Gly-NaOH as the running buffer. The optimum conditions of stacking and separation were: 25 mmol/L Gly-HCl (pH 2.5) as the sample buffer and 50 mmol/L Gly-NaOH (pH 12.3) as the running buffer, 15 kV of applied voltage, 4.82 kPa (0.7 psi) x 20 s of pressure injection, 60.2 cm x 75 microm i.d. (50 cm effective length) of capillary, 214 nm of detection wavelength, 24 degrees C of separation temperature. Under the optimum conditions, the MRB can significantly improve the sensitivity of urine profiling. More than 80 stacking peaks have been observed and more than 10 fold sensitivity enhancement was achieved in contrast with the conventional CZE, which with only ten observable peaks and poor sensitivity. The results indicate that the MRB-induced stacking is a useful and potential tool for urine profiling. Furthermore, the present method is easy to perform, and the preparation of sample is quite simple.