Microextraction in packed syringe/liquid chromatography/electrospray tandem mass spectrometry for quantification of acebutolol and metoprolol in human plasma and urine samples

The aim of the present investigation was to develop a simple, fast, and sensitive method for the determination of acebutolol and metoprolol in human plasma and urine samples. The determination of acebutolol and metoprolol in plasma and urine was performed using micro extraction in packed syringe (MEPS) as a sample preparation method, online with high performance liquid chromatography and tandem mass spectrometry (LC-MS/MS). In MEPS the sampling sorbent was 1 mg polystyrene polymer, which was inserted in a 250 mu L syringe. The lower limits of quantification (LLOQ) for acebutolol and metoprolol were set to 1.0 ng/mL. The accuracy of quality control samples (QC) varied by +/- 10%, and precision (R.S.D.) had a deviation of 1.4-12% for plasma and urine samples. The calibration curve was obtained within the concentration range 1.0-100 ng/mL in both plasma and urine. The regression correlation coefficients (R-2) for plasma and urine samples were >= 0.999 for all runs. The present method is miniaturized, fully automated, robust, and can be easily used for pharmacokinetic and pharmacodynamic studies of acebutolol and metoprolol.