High-performance liquid chromatographic determination of nifedipine, nicardipine and pindolol using a carbon fibre flow-through amperometric detector.

The electrochemical properties of the calcium-channel blockers, nifedipine and nicardipine, and the beta-blocking agent, pindolol, have been exploited for the determination of their concentrations in plasma samples. High-performance liquid chromatography (HPLC) separation was carried out on a cyanopropyl modified column and the drugs were detected in a flow-through carbon fibre microelectrode cell. The chromatographic system was coupled to a column-switching arrangement in order to perform on-line solid-phase extraction of the drugs from spiked human plasma. Preliminary investigations showed the response of the method to be linear over a range of 20-500 ng ml-1 in plasma with a limit of detection of approximately 15 ng ml-1 for each compound.