[Determination of four nucleosides in Banlangen injections using capillary zone electrophoresis]

The contents of cytidine, adenosine, guanosine and uridine in Banlangen Injections were determined by capillary zone electrophoresis. Shorter fused silica capillary (32.5 cm x 50 microm i. d. with effective length of 23.5 cm) was used. The samples were analyzed with 60 mmol/L borate-10% (v/v) 2-propanol-20% (v/v) acetonitrile running buffer at 20 kV voltage (25 degrees C capillary temperature). Pressure injection of 1 kPa x 10 s was employed, and the detection wavelength was 254 nm. Factors of the electrophoresis condition were investigated, such as the kinds and concentration of the electrolyte, buffer pH value, the type and concentration of organic modifier, separation voltage and temperature. The samples were filtered through 0.45 microm membrane, then direct injection was employed. External calibration of peak area versus concentration was used in the determination. Linear calibrations of four nucleosides were obtained within 12.5 - 250 mg/L (r > 0.999 1). The limits of detection (mg/L) were 6.2 of cytidine, 4.6 of adenosine, 6.7 of guanosine, and 9.0 of uridin. The average recoveries of the four nucleosides were between 95.1% - 102.3% with RSDs of 0.3% - 4.9%. The method is simple, rapid, reproducible and accurate. It can be used for the routine analysis of the four nucleosides in Banlangen Injections.