Simultaneous Determination of Eight Tranquilizers in Pork by Ultra-Performance Liquid Chromatography Coupled with Electrospray Tandem Mass Spectrometry

Abstract

An ultra-performance liquid chromatography/electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) method was developed and validated for quantification of eight tranquillizers (chlorpromazine, imipramine hydrochloride, diazepam, nitrazepam, nordazepam, oxazepam, flurazepam, and haloperidol) in pork. Sample pretreatment consisted of extraction by acetonitrile, defatted by n-hexane, and further solid phase extraction by hydrophilic-lipophilic balance (HLB) extraction cartridges. The triple quadrupole mass spectrometer was operated in positive ion mode, and multiple reaction monitoring was used for drug quantification. The method was validated over the concentration ranges of 1.0 ∼ 250 μg kg−1 for the eight tranquillizers. The calibrations were performed in sample matrices, and the interference effect of sample matrices on the ionization was effectively eliminated. Good linear relationship (R2 > 0.99) was observed within the concentration range of 1.0–250 μg kg−1. The average recoveries of the eight tranquillizers spiked at three levels ranged from 63.7 to103.2 % with the relative standard deviation below 11.8 %. The limits of detection were between 0.06 and 0.30 μg kg−1, and the limits of quantification were between 0.2 and1.0 μg kg−1 for all analytes in pork. This validated method has been successfully used to quantify the concentration of the eight tranquillizers in pork samples.