Research On Establishment Of Pesticides High Resolution Mass Spectral Library And Its Application

Efficient analysis of large amounts of raw data for chemical adulterants detection and identification is always a difficult challenge in the field of food safety.The present study proposed a strategy for rapid screening and multiple identification points to confirm of multi pesticide residues in vegetables and fruits using the high performance liquid chromatography coupled to quadrupole-time-of-flight mass spectrometer(HPLC-QTOF/MS)based on a homemade high-resolution accurate mass database(MS~1)and a novel MS/MS spectra library(MS~2).Two accurate mass databases and two collision-induced-dissociation(CID)accurate mass spectra libraries including 427 pesiticide chemicals have been created with two instruments and library softwares supplied by different manufacturers.The mass spectra were acquired under ESI+ mode.The factors such as mass accuracy,retention time of the extracted chromograph and collision energy was checked carefully in the database and library application,which laid a technical and theoretical basis for non-targeted screening.Then,we conducted two kinds of quick and efficient methods on pesticide residues screening in fruits and vegetables based on the MS~1 database and MS~2 library instead of the expensive pesticide stardard references.One of screening methods was established by HPLC-QTOF-MS based on the accurate MS~1 identification and MS~2 confirmation.The proposed screening strategy needed a twoinjection of each sample extract.Firstly,HPLC-Q-TOF/MS in full MS scan mode was conductted and all potential compounds in MS~1 database were matched against the raw data of sample for target screening.Secondly,targeted MS/MS analysis was carried out by a hybrid Q-TOF/MS and the suspect analytes CID product ions were identified by the MS~2 spectra library.To validate the performances the suggested screening technology,the cucumber and orange matrices were prepared by traditional solid phase extraction,spiked with 317 pesticides in three concentration levels,and analyzed by HPLC-Q-TOF/MS.The results showed that screening detection limits(SDLs)of more than 83.9% of pesticides were no more than 10 ?g/kg,and 77.6% of them could be identified by targeted MS/MS coupled with MS~2 library in each matrix.The total false negative rate of the proposed qualitative screening method was as low as 4.7% at 50 ?g/kg.All the results show the proposed strategy is suitable for routine analysis of multi-pesticide residues.The other screening method was established by a UHPLC-TripleTOFTM-MS with an artificial intelligence-based product ion scan mode.The accurate mass screening and CID product ions identification of non-targeted compounds was conducted within one-injection in the proposed screening strategy.The information dependent acquisition(IDA)providing automatic MS to MS/MS switching were conducted and a home-in CID all product ions accurate mass spectra library containing more than 1 700 spectra was retrived for identification.Both qualitative and quantitative validation of the method were carried out.The result showed that 93.2%(97.4%)of the pesticides had the SDL less than 10 ?g/kg(50 ?g/kg)and more than 84.8% of them could be confirmed by accurate MS~2 spectra embodied in the home-made library.Meanwhile,calibration curves covering two orders of magnitude were performed,and they were linear over the concentration range studied for the selected matrices(from 5 to 500 ?g/kg for most of the pesticides).Recoveries between 80% and 110% in four matrices(apple,orange,tomato and spinach)at two spiked levels,10 and 100 ?g/kg,was 88.7% or 86.8%.Furthermore,the overall relative standard deviation(RSD,n=12)for 94.3%(98.1%)of the pesticides in 10 ?g/kg(100 ?g/kg)spiked levels was less than 20%.All indicate well quantitative performance of the method.After verification of the method performance by real samples,a total of 2 583 fruit and vegetable samples purchased randomly from different markets were analyzed by proposed strategies.As a result,5 607 positive findings,and 114 pesticides were identified in 1 869 samples.The approach was proved to be a cost-effective,time-saving and powerful strategy for routine large scope screening of pesticides.