A method involving pyrolysis pretreatment followed by ion chromatography was developed to determine the residual thionyl chloride in levetiracetam. Levetiracetam was combusted at high temperature. After the pyrolysis gas was absorbed, the sulfur in thionyl chloride was converted to sulfate, which were determined by ion chromatography with conductivity detector using potassium hydroxide as the mobile phase. The linearity, limits of detection and quantification, and recovery of the method were evaluated. The average rate of conversion of thionyl chloride to sulfate was 98.2%, indicating good conversion efficiency. The limit of detection for sulfate was 8.85 μg/L. The relative standard deviation of the amount of SOCl2 calculated based on the concentration of sulfate was 2.70%, indicating good repeatability. The recovery for sulfate was 96.0–104%. The results suggest that pyrolysis combined with ion chromatography is an effective method to determine residual thionyl chloride in levetiracetam.

中文翻译：

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热解结合离子色谱法高效测定抗癫痫药左乙拉西坦中的痕量亚硫酰氯

开发了一种包括热解预处理和离子色谱法的方法来测定左乙拉西坦中的残留亚硫酰氯。左乙拉西坦在高温下燃烧。热解气被吸收后，亚硫酰氯中的硫转化为硫酸盐，用氢氧化钾为流动相的离子色谱和电导检测器测定。评估了该方法的线性度、检测限和定量限以及回收率。亚硫酰氯转化为硫酸盐的平均转化率为98.2%，表明转化效率良好。硫酸盐的检测限为 8.85 μg/L。以硫酸盐浓度计算的 SOCl2 量的相对标准偏差为 2.70%，重复性良好。硫酸盐的回收率为 96.0-104%。