高效液相色谱法测定甲基多巴的含量及有关物质

目的: 建立同时测定甲基多巴含量及有关物质的HPLC方法。 方法: 采用反相高效液相色谱法,色谱柱为Venusil XBP C₁₈(4.6 mm×250 mm,5 μm)柱,以甲醇-0.1 mol·L^-1磷酸溶液(用稀氨水调节pH至3.0)为流动相进行梯度洗脱(0~8 min,10∶ 90;8~20 min,10∶ 90→75∶ 25;20~25 min,75∶ 25;25~26 min,75∶ 25→10∶ 90;26~35 min,10∶ 90),柱温35 ℃,流速1.0 mL·min^-1,检测波长280 nm。 结果: 甲基多巴峰与各主要杂质及强制破坏产生的降解产物的杂质峰均分离良好,甲基多巴浓度在21.60~194.4 μg·mL^-1范围内,与峰面积呈良好的线性关系,回归方程A=1.338×10⁴ C-5.369×10³,r＝1.0000(n=7);重复性试验RSD为0.41%(n=6);平均加样回收率为99.9%(RSD=0.48%,n=9);最低检测限为2.084 ng;供试品溶液在24 h内稳定。 结论: 本方法准确、灵敏、可靠,专属性强,可用于甲基多巴的质量控制。

Objective: To establish an HPLC method to determine the content and its related substances of methyldopa. Methods: The analysis was achieved on a Venusil XBP C₁₈ column (250 mm×4.6 mm,5 μm) using a mobile phase of methonal-0.1 mol·L^-1 phosphoric acid solution(adjusting the pH value to 3.0 with the dilute aqua ammonia) with gradient elution in a total run time of 35 min(0 min,10∶90;8 min,10∶90;20 min,75∶25;25 min,75∶25;26 min,10∶90;35 min,10∶90).The flow rate was 1.0 mL·min^-1and the detection wavelength was at 280 nm and the column temperature was 35 ℃. Results: There was good resolution among the peak of methyldopa,the main related substances and the degradable impurities by destroyed.There was a good linear relationship between the peak area and the concentration of methyldopa in the range of 21.60-194.4 μg·mL^-1 (r=1.0000,n=7).Regression equation can be expressed by A=1.338×10⁴ C-5.369×10³,r＝1.0000(n=7).The average recovery was 99.9%(RSD=0.48%,n=9) and the limit of detection was 2.084 ng.The solution was stable for 24 hours. Conclusion: The method is specific,accurate,sensitive and can be used for the determination of methyldopa.