Abstract: A capillary zone electrophoresis (CZE) method was developed for the simultaneous determination of cefoperazone sodium and tazobactam sodium in the injectable powder of cefoperazone sodium and tazobactam sodium with hydrochlorothiazide as the internal standard. The operation was carried out on a quartz capillary (75 cm×75 μm i.d., 63 cm effective length). The electrophoretic conditions were as follows: 40 mmol/L borax solution as the back ground electrolyte (BGE), 12.0 kV applied voltage, 220 nm as the detection wavelength; the sample solution was injected by hydraulic pressure for 10 s at the height of 10 cm. The cefoperazone and tazobactam showed good linear relationship in the ranges of 0.25~3.96 g/L and 0.062~0.99 g/L with the correlation coefficients of 0.9995 and 0.9996, respectively. The relative standard deviations of relative peak areas were less than 3%. The preparation was stable in 208 min. The recovery results met the methodology requirements. The method is simple, rapid, reproducible, and suitable to control the quality of cefoperazone sodium and tazobactam sodium injectable powder.

Key words: cefoperazone sodium and tazobactam sodium for injection, compound drugs, tazobactam sodium, capillary electrophoresis （CE）, cefoperazone sodium