目的 建立反相高效液相色谱法测定左卡尼汀片中已知杂质左卡尼汀杂质A。方法 色谱柱为Waters μBondapakTM NH2（300 mm×3.9 mm，10 μm）；流动相为0.05 mol/L磷酸二氢钾溶液（用稀磷酸调节pH值4.0）–乙腈（35∶65）；体积流量1.0 mL/min；检测波长为205 nm；进样量20 μL；柱温为30 ℃，外标法计算。结果 片剂中左卡尼汀杂质A与左卡尼汀能够完全分离，空白辅料不干扰测定，左卡尼汀杂质A在5.01～75.15 μg/mL线性关系良好（r＝1.000）。左卡尼汀杂质A平均回收率为100.8%（RSD＝1.16%，n＝9）。结论 经方法学考察，左卡尼汀片中已知杂质左卡尼汀杂质A测定方法的专属性强，准确可靠，易于操作。左卡尼汀片中已知杂质左卡尼汀杂质A的量较低并且稳定。

Objective To develop a RP-HPLC method to determine levocarnitine impurity A in Levocarnitine Tablets. Methods The chromatographic conditions included Water μBondapakTM NH2 column (300 mm × 3.9 mm, 10 μm) and 0.05 mol/L KH2PO4 (adjusted to pH 4.0 with diluted phosphoric acid)-acetonitrile (35∶65) as the mobile phase at a flow rate of 1.0 mL/min, detected at 205 nm, injection volume was 20 μL, and the column temperature was 30 ℃, using external standard method to calculate. Results Impurity A and levocarnitine could be completely separated, and blank recipients did not influence the determination. There was a good linearity in the range of 5.01 — 75.15 μg/mL (r = 1.000). The average recovery of levocarnitine impurity A was 100.8% (RSD = 1.16%, n = 9). Conclusion The established method is high selective, simple, and accurate. Amount of levocarnitine impurity A is little and stable in Levocarnitine Tablets.