Quantitation of verapamil and norverapamil in postmortem and clinical samples using liquid-liquid extraction, solid phase extraction, and HPLC

HPLC method for determination of verapamil in human plasma after solid-phase extraction

“…Some of them employ fluorescence detection [3][4][5][6][7][8][9][10], very few employ spectrophotometric detection in the UV range [11,12], whereas mass spectrometric detection is used in the recent developed methods [13][14][15][16][17].…”

“…As for the sample preparation procedures employed prior to the HPLC determination of verapamil, there is a diversity in the speed and complexity of the clean-up methods starting from direct determination of verapamil from rat plasma [7], through using only deproteinization of the plasma samples [11,13] to the more complex ones such as liquid-liquid extraction (LLE) using various organic solvents [3,4,6,9,10,15] and solid-phase extraction (SPE) with various adsorbents [4,8,9,17]. The most sophisticated sample preparation procedures employ automated column switching techniques for on-line sample preparation [5,7,8,12].…”

“…SPE using C 18 SepPak cartridges was used for extraction of verapamil and its metabolites in serum samples (recovery: 87.7 ± 5.8 to 92.7 ± 4.0%) and SPS C 8 pre-column for on-line SPE (recovery: 94.34 to 98.25%) [8]. Verapamil and norverapamil in blood, liver and kidney using HPLC with fluorescence detection with prior LLE and SPE with C 2 silica phases has been used and the LLE procedure proved to be simpler, less expensive and more versatile than SPE especially for complex biological specimens such as tissue samples [9]. A sample preparation procedure employing SPE with a mixed-mode sorbent (reversed phase and cation exchanger) has been developed for the determination of 14 drugs in whole blood including verapamil with high recoveries for most of them (N 96% fro verapamil) [17].…”

Application of restricted access material (RAM) with precolumn-switching and matrix solid-phase dispersion (MSPD) to the study of the metabolism and pharmacokinetics of Verapamil

“…For the analysis of low levels of metabolites and the parent compound in biological samples, sample preparation, such as extraction, preconcentration and clean-up steps, are often required to improve sensitivity and selectivity. Traditional procedures for sample preparation, such as solvent extraction [7,11] and solid-phase extraction [12], are time-consuming and labor-intensive, require large volumes of sample and (toxic) solvent, and are not very selective.…”

“…In the majority of the existing publications describing methods for the determination of Verapamil and its main metabolites in biological samples, high-performance liquid chromatography [5,6,7] and HPLC-MS [8,9,10] were used. For the analysis of low levels of metabolites and the parent compound in biological samples, sample preparation, such as extraction, preconcentration and clean-up steps, are often required to improve sensitivity and selectivity.…”