ABSTRACT
To response to the need for a rapid, cost-effective, eco-friendly and efficient extraction process, a sensitive method for the determination of ethylenethiourea (ETU) in food matrices by high-performance liquid chromatography-mass spectrometry (HPLC-LC/MS) was developed and validated. ETU was extracted from food commodities with methanol, cleaned up by alumina-SPE column, and then determined by HPLC-MS/MS. The MS detection was operated in positive ionization mode. For confirmation of target compound, two precursor ion>product ion transitions were selected by multi-reaction monitoring mode (MRM). The method showed good linearity with correlation coefficient higher than 0.9950. Recoveries at three spiked levels (10, 50, 100 ng/g) in random selected food matrices were in range of 71-121% with RSDs not larger than 25%. The limit of quantitation for the analyte was estimated at 5 ng/g.
Subject(s)
Chromatography, High Pressure Liquid/methods , Ethylenethiourea/analysis , Ethylenethiourea/isolation & purification , Food Contamination/analysis , Fungicides, Industrial/analysis , Solid Phase Extraction/methods , Tandem Mass Spectrometry/methods , Food AnalysisABSTRACT
Products labelled as containing extracts from two mushrooms (cordyceps plus reishi) and the juices from açaí, goji, mangosteen, noni, pomegranate, and sea buckthorn have been analysed for 174 different pesticides, using the validated QuEChERS method for sample preparation and electrospray LC-MS/MS in the positive ion mode for analysis. Pesticides were found in 10 of the 21 samples analysed. Most pesticides found were below the tolerance levels (1-6 µg/g, depending on the pesticide), but some were not. This included boscalid, dimethomorph, iprovalicarb, pyridaben, pyrimethanil, and imazalil, for which there is no tolerance reported or zero tolerance in any fruit. However, genuine açaí that was harvested in the state of Pará and lyophilised in Rio de Janeiro had no detectable pesticides, when analysed by both LC-MS/MS and GC-MS/MS, which can detect 213 more pesticides and industrial chemicals. Likewise no pesticides were found in one sample each of cordyceps plus reishi, sea buckthorn and noni.
