evaluation of quechers sample preparation and gc mass spec-trom¬etry method for the determination of 15 pesticide resi¬dues in tomatoes used in salad production plants

background: the present study was the first attempt for determination and measurement of pesticide residues in tomatoes used in salad production plants in isfahan, central iran. methods: a multiresidue method based on modified quechers (quick, easy, cheap, effective, rugged and safe) sample preparation, followed by gas chromatography mass spectrometry (gc–ms) was developed and validated for the determination of 15 pesticides (permethrin , primicarb , dichlorvos , diazinone , fenpropathrin , carbaryl , chlorpyrifos, malathion, chlortalonil, brompropilate, propargit, tetradifone, phosalone, iprodion and endosulfane) from different classes. the recovery yields ranged from 83.84 to 119.73%and the relative standard deviation (rsd) was below 20.54%. the limits of detection (lods) were between 1.63to 10.5 mg/kg and the limits of quantifications (loqs) were between 5.43to35 mg/kg. the method has been successfully applied to the analysis of 22 tomato samples obtained from salad production plants in isfahan in sep to dec 2014. results: an amount of 31.81% of samples showed contamination above maximum residue levels (mrls) with pesticides. in addition, 13.6% of samples had contamination with diazinone and 18.18% of samples with chlorpyrifos. conclusion: a full consideration is essential for tomatoes used in salad and food productions. it suggests a need for revision of the current trend of supervision for tomatoes and other vegetables presented in wholesale markets. in all, the study confirms that pesticide residue determination in food products, especially in raw fruits and vegetables, is a very demanding task in public health safety and trade.