Mell L D, Gustafson A B
Clin Chem. 1978 Jan;24(1):23-6.
We describe a chromatographic method, in which 3,4-dihydroxybenzylamine is used as the internal standard, for determining free methyldopa in human urine. The drug was adsorbed onto alumina, eluted, and the eluate directly injected onto a reversed-phase column (octadecyl-bonded silica stationary phase), with dilute acetate buffer (pH 2.7) as the mobile phase and ultraviolet detection at 280 nm facilitated. Methyldopa is well separated from other urinary biogenic amines present in the alumina extract, and other commonly used antihypertensives and diuretics do not interfere with the analysis. The sensitivity of the method is adequate to quantify 8.0 mg of methyldopa per liter in 30 ml of sample; the lower limit of detection is 25 ng. Analytical recovery for methyldopa varied from 95 to 102% with within-run and day-to-day coefficients of variation of 2.7 (n = 10) and 3.8% (n = 5), respectively. This procedure is readily adaptable for use in studies of the pharmacokinetics of methyldopa and to routine clinical laboratory use.
我们描述了一种色谱方法，该方法使用3,4 - 二羟基苄胺作为内标，用于测定人尿中的游离甲基多巴。药物被吸附到氧化铝上，洗脱后，洗脱液直接注入反相柱（十八烷基键合硅胶固定相），以稀醋酸盐缓冲液（pH 2.7）作为流动相，并在280 nm处进行紫外检测。甲基多巴与氧化铝提取物中存在的其他尿中生物胺能很好地分离，其他常用的抗高血压药和利尿剂不干扰分析。该方法的灵敏度足以在30 ml样品中定量每升8.0 mg的甲基多巴；检测下限为25 ng。甲基多巴的分析回收率在95%至102%之间，批内变异系数为2.7（n = 10），日间变异系数为3.8%（n = 5）。该方法易于应用于甲基多巴的药代动力学研究及常规临床实验室检测。
