Determination of Chlormequat and Mepiquat Residues in Food by High Performance Liquid Chromatography-Tandem Mass Spectrometry

KeyWord:chlormequat  mepiquat  HPLC  tandem mass spectrometry  food

Abstract:

      A high performance liquid chromatography-electrospray ionization tandem mass spectrometric£¨HPLC-ESI MS/MS£© method was developed for the determination of two plant growth regulators,eª±g.chlormequat and mepiquat,in rice,wheat flour,pear,tomato and ketchup samples.The samples were extracted with methanol-water£¨1¡Ã1,by volume£© and cleaned up on a Strata X C solid phase extraction column.The target compounds were separated on an Agilent ZORBAX RX SIL£¨1.8 ¦Ìm,3.0 mm¡Á100 mm£© chromatographic column by equivalently elution using acetronitrilie-10 mmol/L ammonium acetate£¨containing 0.1% formic acid £© as mobile phase.The residues of chlormequat and mepiquat were determined under the electrospray positive ionization£¨ESI+£© and multiple reaction monitoring£¨MRM£© mode,and quantified by the matrix matched external standard method.The calibration curves for chlormequat and mepiquat showed good linearities in the range of 0.20-10 ¦Ìg/L with correlation coefficients£¨r2£© no less than 0.999 0.The limits of quantitation£¨S/N¡Ý10£© and limits of detection£¨S/N¡Ý3£© were in the range of 0.05-0.15 ¦Ìg/kg and 0.02-0.05 ¦Ìg/kg,respectively.The average recoveries of chlormequat and mepiquat from rice,wheat flour,pears,tomato and ketchup matries at three spiked levels of 0.20£¬5.0,10 ¦Ìg/kg were in the range of 82%-102% and 80%-103%,respectively,with relative standard deviations of 3.8%-9.6% and 1.9%-10.0%,respectively.The method was sensitive and accurate,and could meet the requirements for the determination of chlormequat and mepiquat in foods.