HPLC法测定左旋多巴的有关物质

目的：建立RP-HPLC测定左旋多巴有关物质的方法。方法：采用Welch Xtimate^TM C₁₈色谱柱（250 mm×4.6 mm，5 μm），以甲醇-0.05 mol·L^-1磷酸二氢钠缓冲液（pH 3.0）为流动相进行梯度洗脱，柱温30 ℃，流速1.0 mL·min^-1，检测波长280 nm。结果：左旋多巴与各已知杂质及强制破坏产生的降解产物均分离良好，（2S）-2-氨基-3-（2，4，5-三羟基苯基）丙氨酸、左旋多巴、L-酪氨酸、3-甲氧基多巴、二甲氧基多巴和二甲氧基多巴酰化物浓度分别在0.2020~10.10 μg·mL^-1（r=0.9999）、0.1017~10.07 μg·mL^-1（r=1.000）、0.1046~10.46 μg·mL^-1（r=1.000）、0.08552~8.552 μg·mL^-1（r=0.9999）、0.09979~9.979 μg·mL^-1（r=1.000）和 0.09537~9.537 μg·mL^-1（r=1.000）范围内与峰面积呈良好的线性关系。已知杂质的平均回收率分别为100.4%、100.9%、99.8%、99.1%和99.1%，RSD依次为4.1%、4.5%、4.3%、3.9%和3.5%（n=9）；上述化合物精密度试验RSD分别为1.7%、0.37%、0.56%、1.4%、0.39%和1.2%（n=6）。结论：本方法专属性强、准确、灵敏，可用于左旋多巴的有关物质检测和质量控制。

Objective: To establish an HPLC method for the determination of related substances of levodopa. Methods: The determination was performed on a Welch Xtimate^TM C₁₈ column (250 mm×4.6 mm,5 μm),with a mobile phase consisting of a mixture of methanol and 0.05 mol·L^-1 sodium dihydrogen phosphate buffer (pH 3.0) by gradient elution.The column temperature was set at 30 ℃ with a flow rate of 1.0 mL·min^-1,and the detective wavelength was 280 nm. Results: The known impurities and degraded products by forced destruction were completely separated from levodopa.The calibration curves for (2S)-2-amino-3-(2,4,5-trihydroxyphenyl) propanoic acid, levodopa,L-tyrosine,3-methoxytyrosine,veratrylglycine and veratrylglycine acylate revealed good linearities over the ranges of 0.2020-10.10 μg·mL^-1 (r=0.9999),0.1017-10.07 μg·mL^-1 (r=1.000),0.1046-10.46 μg·mL^-1 (r=1.000),0.08552-8.552 μg·mL^-1 (r=0.9999),0.09979-9.979 μg·mL^-1 (r=1.000) and 0.09537-9.537 μg·mL^-1 (r=1.000),respectively.The recoveries of the impurities were 100.4% with RSD of 4.1%,100.9% with RSD of 4.5%,99.8% with RSD of 4.3%,99.1% with RSD of 3.9% and 99.1% with RSD of 3.5%,respectively.The precision of the above compounds were 1.7%,0.37%,0.56%,1.4%,0.39% and 1.2%,successively. Conclusion: The method is specific,accurate and sensitive,which can be used for the test of the related substances of levodopa and quality control.