Multiresidue method of analysis for determination of 150 pesticides in grapes using quick and easy method (QuEChERS) and LC-MS/MS determination

Multiresidue method for determination of 150 pesticides in grapes has been validated using quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction method followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) determination. The chosen pesticides are belonging to various chemical groups; they are registered in Egypt or most frequently detected in fruits and vegetables in Egyptian market. Grape samples were extracted by shaking with acetonitrile. Phase separation was induced by shaking with buffer salt mixture consisting of magnesium sulfate, sodium chloride, disodium hydrogen citrate sesquihydrate and trisodium citrate dihydrate. The sample was centrifuged and an aliquot of the clear solution dried by shaking with magnesium sulphate. The extract was centrifuged and an aliquot of the clear solution evaporated, redissolved in methanol/water buffer solution and injected into LC-system. Quantitation and identity confirmation was attained by using atmospheric pressure electrospray positive ionization LC-MS/MS in multiple reaction monitoring (MRM) mode. The recoveries at three different concentration levels (0.01, 0.05 and 0.1 mg/kg) ranged from 70 to 110%. The repeatability expressed as relative standard deviation (RSD,) was 1-25% (n = 6). Matrix matched standards were used to compensate for the matrix effect.