Identification Of Pesticide Residues In Common Fruits And Vegetables By Gas Chromatography-quadruple Time Of Flight Mass Spectrometry

With the development of the economic and improvement of people’s consumption, the fruitand vegetable market was enlarged. Thereupon, food safety incidents have happened occasionally,pesticide residues have been the serious threaten of the public health. For this reason, strictlegislation was established at EU, Japanese and United States. In the EU directive, typicalpesticides’ maximum residue levels (MRLs) are0.01mg/kg, specific pesticide MRLs as low as0.003to0.008mg/kg. With the strictly limited requirement, a higher requirements of detectionmethods was proposed, and much technical barriers on the fruit and vegetable products export wasfaced. Thus, to establish an accurate and effective method of pesticide residues detect is of greatsignificance.In this article, a new screening method was developed for detecting152pesticidemulti-residues in different chemical classes using CarbonNH2cartridge solid-phase extraction (SPE)and gas chromatography-quadrupole time of flight mass spectrometry (GC-QTOF MS). The mainresults are as follows:(1)A first stage (MS1) accurate mass database and second stage (MS2) library include152pesticides were established based on the GC-QTOF MS.(2) Cabbage, tomato, pear were selected as typical fruits and vegetables, which extracted with40mL1%acetic acid-Acetonitrile, after eliminate water by salting out effect, the extract waspurified by CarbonNH2cartridge, the residues was redissolved by hexanes, the final solution wasfiltered and analyzed by GC-QTOF MS. Spiked and detected all the152pesticides at twoconcentration level of5.0and10.0μg/kg, the recoveries in the range of70%-120%were91.45%、94.08%for cabbage，88.2%、88.8%for tomato，86.84%、92.1%for pear. The detection limit (LOD)were0.01~8.57μg/kg,0.01~8.79μg/kg,0.02~11.76μg/kg respectively.In addition, in chromatography-mass spectrometry analysis, matrix effect is the most importantfactor affecting the accurate quantification of pesticide residues. In this paper, we evaluated thereason of matrix effect arising and impact, we found that the matrix-induced response enhancement is the main factor in gas chromatography analysis, and the organic phosphorus and organic nitrogenpesticides is more pronounced. The cause of matrix effect is the existance of active site in theinjector, column, and detector, and the adsorption of target pesticides in the active site will affect themeasurement results seriously. The use of matrix-matched standard solution quantitatively will toreduce the matrix effects significantly.Through the MS1accurate mass database analysis, we can get some pesticides identify andfind some suspected pesticides, the suspected pesticide analysis and identified MS2library. Thismethod realized the real identification of pesticide in complex matrix with reliable and effective,and provides a guarantee for the analysis of pesticides with less characteristic ions; the analysisscope was expanded.