Simultaneous determination of beta-blockers in human plasma using liquid chromatography-tandem mass spectrometry

A detailed procedure for the analysis of four beta-blockers, acebutolol, labetalol, metoprolol and propranolol, in human plasma by high-performance liquid chromatography (LC)-tandem mass spectrometry (MS-MS) using an MSpak GF column, which enables direct injection of crude plasma samples, is presented. Protein and/or macromolecule matrix compounds were eluted first from the column, while the drugs were retained on the polymer stationary phase of the MSpak GF column. The analytes retained on the column were then eluted into an acetonitrile-rich mobile phase using a gradient separation technique. All drugs showed base peak ions due to [M + H]+ ions by LC-MS with positive ion electrospray ionization, and the product ions were produced from each [M + H]+ ion by LC-MS-MS. Quantification was performed by selected reaction monitoring. The recoveries of the four beta-blockers spiked into plasma were 73.5-89.9%. The regression equations for all compounds showed excellent linearity in the range 10-1000 ng/mL of plasma, with the exception of propranolol (10-800 ng/mL). The limits of detection and quantification for each drug were 1-3 and 10 ng/mL, respectively, of plasma. The intra- and inter-day coefficients of variation for all drugs in plasma were not greater than 10.9%.