Determination of Pemoline in Feeds Using Ultra-performance Liquid Chromatography-Electrospray Tandem Mass Spectrometry

An ultra-performance liquid chromatographic method with tandem mass spectrometric determination was developed for determination of pemoline in feeds.The sample was extracted by methanol-acetonitrile solution.The extract was evaporated to dryness under nitrogen,and redissolved by methanol and water,sequencely.The mixture was degreased by ethyl acetate and cleaned up on a Waters Oasis HLB solid phase extraction column.The separation of compounds was carried on a BEH C18 column(2.1 mm×50 mm i.d.,1.7 μm) by a gradient elution using methanol(A)-water(added 0.1% formic acid)(B) as mobile phase with a flow rate of 0.3 mL/min.The analyte was detected by tandem quadrupole mass spectrometry under multiple reaction monitoring(MRM) mode with positive electrospray ionization(ESI).The method was quantified by external standard method.The experimental conditions were optimized.Under the optimal conditions,the calibration curve showed a good linearity over the concentration of pemoline in the range of 1-500 μg/L with a correlation coefficient more than 0.999.The detection limit(LOD) and the quantitative limit(LOQ) of pemoline were 2.0 μg/kg and 5.0 μg/kg,respectively.The average recoveries from spiked feeds samples at four concentration levels of 5.0,10,50 and 200 μg/kg ranged from 77% to 86% with relative standard deviations of 4.4%-7.9%.The method showed a good repeatability and high sensitivity,and was suitable for the determination and confirmation of pemoline in feeds.