On-line SPE Using Ionic Liquid-Based Monolithic Column for the Determination of Antihypertensives in Human Plasma

A poly(ionic liquid-glycidylmethacrylate-co-ethyleneglycol dimethacrylate) monolithic column was prepared via in situ free-radical polymerisation and used as an on-line solid-phase extraction column. The obtained monolithic column was characterized by scanning electron microscopy, Fourier transform infrared spectrometer, nitrogen adsorption–desorption measurement, and mercury intrusion porosimetry, which showed a relatively uniform and porous structure. During the on-line solid-phase extraction–high performance liquid chromatography protocol, nifedipine, nitrendipine, and felodipine were separated efficiently from human plasma using a methanol–water linear gradient at a flow rate of 1.0 mL min −1 . The extraction efficiency for the targets was satisfactory with no matrix interference. Under the optimized extraction conditions, the linear regression coefficient was >0.9973; precisions for inter- and intra-day assays presented as relative standard deviations were less than 7.29 %, and the accuracy and recovery was in the range of 96–105 and 90–106 %, respectively. As a result, the polymerization monolithic column exhibited high selectivity and good permeability, and it was feasible to be used as an on-line SPE column. Meanwhile, validation assays also demonstrated acceptable sensitivity and precision for simultaneous quantitative screening of nifedipine, nitrendipine, and felodipine in human plasma.