目的:建立二阶导数光谱法测定海仙灵口服液中甲硝唑含量的方法。方法:用二阶导数光谱法直接测定海仙灵口服液中甲硝唑含量,276.8nm波长处测定振幅D值。结果:甲硝唑在5.15～25.75μg·ml~(-1)范围呈良好线性关系;其回归方程为D=0.835×10~(-4)C-1.1×10~(-4)(r=0.9970),平均回收率99.71%、RSD=2.39%(n=5)。结论:本方法操作简单、准确,可用于测定海仙灵口服液中甲硝唑含量。 Objective: To establish a method for the determination of metronidazole in Haixianling oral liquid by second derivative spectrometry. METHODS: The metronidazole content in Haixianling oral liquid was measured directly by second derivative spectrophotometry, and the amplitude D value was measured at a wavelength of 276.8 nm. RESULTS: Metronidazole showed a good linear relationship in the range of 5.15-25.75 μg·ml-1. The regression equation was D=0.835×10-4 C-1.1×10-4 (r= 0.9970), average recovery 99.71%, RSD = 2.39% (n = 5). Conclusion: This method is simple and accurate. It can be used to determine the metronidazole content in Haixianling oral liquid.