Hubert P, Chiap P, Crommen J
Laboratory of Drug Analysis, University of Liège, Belgium.
J Pharm Biomed Anal. 1991;9(10-12):883-7. doi: 10.1016/0731-7085(91)80018-5.
An automatic liquid-solid extraction (LSE) procedure to be coupled to HPLC for the determination of diltiazem and desacetyldiltiazem in plasma has been developed. The LSE operations are performed on disposable extraction cartridges (DECs) by means of a sample processor equipped with a robotic arm holding a needle through which the different liquids are dispensed. The operating parameters of LSE have been optimized with respect to recovery, detectability and reproducibility by using, whenever possible, aqueous solutions of the analytes. Different kinds of DECs have been tested. For the compounds studied, DECs filled with 50 mg of cyanopropyl silica have been selected. The influence of the pH of the buffer used in the washing step has been studied, leading finally to the selection of the same phosphate buffer (pH 7.4) as in the HPLC mobile phase. The minimum volume of methanol which still gives a nearly complete elution of the analytes from the extraction cartridges has been determined. Under these conditions, a high sensitivity can be obtained without an evaporation step. Moreover, the volume of buffer to be added to the methanolic eluate before injection into the HPLC system has been optimized in such a way that a focusing effect is obtained at the top of the analytical column while the dilution of the extract is minimized.
已开发出一种与高效液相色谱（HPLC）联用的自动液-固萃取（LSE）方法，用于测定血浆中的地尔硫䓬和去乙酰地尔硫䓬。LSE操作通过配备有机械臂的样品处理器在一次性萃取柱（DEC）上进行，机械臂上装有一根针，通过该针可分配不同的液体。通过尽可能使用分析物的水溶液，对LSE的操作参数在回收率、可检测性和重现性方面进行了优化。测试了不同种类的DEC。对于所研究的化合物，选择了填充有50mg氰丙基硅胶的DEC。研究了洗涤步骤中所用缓冲液pH值的影响，最终选择了与HPLC流动相相同的磷酸盐缓冲液（pH 7.4）。确定了仍能使分析物从萃取柱中几乎完全洗脱的甲醇最小体积。在这些条件下，无需蒸发步骤即可获得高灵敏度。此外，对注入HPLC系统之前添加到甲醇洗脱液中的缓冲液体积进行了优化，使得在分析柱顶部获得聚焦效果，同时萃取物的稀释最小化。
