Rapid High-Performance Liquid Chromatographic Screening for Calcium Channel-Blocking Drugs in Human Plasma Samples

A high-performance liquid chromatographic method is presented for the simultaneous identification and quantification of six commonly prescribed calcium channel-blocking drugs. Single-step extraction was achieved from alkaline samples with ether-dichloromethane (80:20, vol/vol), using thymol as an internal standard. A Novapak C18 column was used, with a mobile phase of methanol-tetrahydrofuran-phosphate buffer pH 2.6 (50:5:45, vol/vol). Detection was carried out at 240 nm.