Faculty of Pharmacy, Rhodes University, Grahamstown, 6140, South Africa.
Talanta. 2011 Jan 15;83(3):1037-49. doi: 10.1016/j.talanta.2010.11.025. Epub 2010 Nov 18.
An accurate, sensitive and specific high performance liquid chromatography-electrochemical detection (HPLC-ECD) method that was developed and validated for captopril (CPT) is presented. Separation was achieved using a Phenomenex(®) Luna 5 μm (C(18)) column and a mobile phase comprised of phosphate buffer (adjusted to pH 3.0): acetonitrile in a ratio of 70:30 (v/v). Detection was accomplished using a full scan multi channel ESA Coulometric detector in the "oxidative-screen" mode with the upstream electrode (E(1)) set at +600 mV and the downstream (analytical) electrode (E(2)) set at +950 mV, while the potential of the guard cell was maintained at +1050 mV. The detector gain was set at 300. Experimental design using central composite design (CCD) was used to facilitate method development. Mobile phase pH, molarity and concentration of acetonitrile (ACN) were considered the critical factors to be studied to establish the retention time of CPT and cyclizine (CYC) that was used as the internal standard. Twenty experiments including centre points were undertaken and a quadratic model was derived for the retention time for CPT using the experimental data. The method was validated for linearity, accuracy, precision, limits of quantitation and detection, as per the ICH guidelines. The system was found to produce sharp and well-resolved peaks for CPT and CYC with retention times of 3.08 and 7.56 min, respectively. Linear regression analysis for the calibration curve showed a good linear relationship with a regression coefficient of 0.978 in the concentration range of 2-70 μg/mL. The linear regression equation was y=0.0131x+0.0275. The limits of detection (LOQ) and quantitation (LOD) were found to be 2.27 and 0.6 μg/mL, respectively. The method was used to analyze CPT in tablets. The wide range for linearity, accuracy, sensitivity, short retention time and composition of the mobile phase indicated that this method is better for the quantification of CPT than the pharmacopoeial methods.
本文介绍了一种用于卡托普利（CPT）的准确、灵敏、特异的高效液相色谱-电化学检测（HPLC-ECD）方法。采用 Phenomenex® Luna 5μm（C18）柱，以磷酸盐缓冲液（pH3.0 调至）：乙腈 70:30（v/v）为流动相，实现分离。在“氧化筛选”模式下，使用全扫描多通道 ESA 库仑检测器，上游电极（E1）设定为+600mV，下游（分析）电极（E2）设定为+950mV，同时保护电极的电势保持在+1050mV，进行检测。检测器增益设定为 300。采用中心复合设计（CCD）进行实验设计，以促进方法开发。研究了流动相 pH 值、摩尔浓度和乙腈（ACN）浓度，这些是建立 CPT 和用作内标物的环嗪（CYC）保留时间的关键因素。进行了 20 次实验，包括中心点，并根据实验数据推导出 CPT 保留时间的二次模型。该方法按照 ICH 指南进行了线性、准确性、精密度、定量和检测限的验证。结果表明，该系统对 CPT 和 CYC 产生了尖锐且良好分离的峰，保留时间分别为 3.08 和 7.56min。校准曲线的线性回归分析显示，在 2-70μg/mL 的浓度范围内，具有良好的线性关系，回归系数为 0.978。线性回归方程为 y=0.0131x+0.0275。检测限（LOQ）和定量限（LOD）分别为 2.27 和 0.6μg/mL。该方法用于分析片剂中的 CPT。线性范围宽、准确性高、灵敏度高、保留时间短、流动相组成合理，表明该方法比药典方法更适合 CPT 的定量分析。
