Rapid determination of phenoxy acid residues in rice by modified QuEChERS extraction and liquid chromatography-tandem mass spectrometry

摘要

A new method for the analysis of phenoxy acid herbicide residues in rice,based on the use of liquid extraction/partition and dispersive solid phase extraction(dispersive-SPE)followed by ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry(UPLC-ESI-MS/MS),is reported.5%(v/v)formic acid in acetonitrile as the extraction solvent and inclusion of citrate buffer helped partitioning of all the analytes into the acetonitrile phase.The extract was then cleaned up by dispersive-SPE using C18 and alumina neutral as selective sorbents.Further optimization of sample preparation and determination allowed recoveries of between 45 and 104% for all 13 phenoxy acid herbicides with RSD values lower than 13.3% at 5.0 mu g kg~(-1)concentration level.Limit of detections(LODs)of 0.5 mu g kg~(-1)or below were attained for all 13 phenoxy acids.Quantitative analysis was done in the multiple-reaction monitoring(MRM)mode using two combinations of selected precursor ion and product ion transition for each compound.This developed method produced relatively higher recoveries of the acid herbicides with a smaller range of variation and less susceptibility to matrix effects,than the original QuEChERS(Quick,Easy,Cheap,Effective,Rugged,and Safe)method.