The Research Of Multiple Residue Analysis Of Four Chiral Pesticides In Fruit And Tea

Nowadays in china, there are almost 40% of commercial pesticides are chiral compounds, and the proportion is increasing year by year. Different enantiomers of chiral pesticides could make differences in toxicity and other fields, so developing the methods of chiral enantiomers of pestisides has great significances in detection, quantitative and control chiral enantiomers in environment. A simultaneously chiral separation and residue determination method for enantiomers of four pestisides(propiconazole, diniconazole,cis-epoxiconazole and acephate) in apple, grape and tea was first developed and validated by Ultra Performance Convergence Chromatography Quadrupole Time-of-Flight Mass Spectrometry(UPC~2-QTOF/MS) in this paper.There are two aspects of optimization in this topic, which are pretreatment and instrumental analysis. Firstly, we chose Ultra Performance Convergence Chromatography(UPC~2) to separate chiral enantiomers of pestisides, campared the effect on enantiomeric separation with six different chiral column(Lux Cellulose-1, Lux Cellulose-2, Lux Cellulose-3, Lux Cellulose-4, Lux Amylose-2 and ChromegaChiral CCA), and optimized the various parameters(such as modifiers and its proportion of mobile phase, flow rate of mobile phase, column temperature, automated backpressure regulator(ABPR), and assisted solvent and its flow rate). Then, in the process of optimization for extraction and purification, we compared the recovery of four chiral compounds which through extraction of pure acetonitrile or the mixture of acetonitrile and water combined with different dissolved-loading solution(water, acetonitrile/water(1:1, v/v), acetonitrile and acetonitrile/benzene(3:1, v/v)), and coupled with two different eluants(acetonitrile and acetonitrile/benzene(3:1, v/v)).Under the premise of best result of enantiomeric separation and recovery, the method condition finally chose Chromega Chiral CCA column as chiral stationary phase(CSP)with mobile phase of CO2/IPA(95/5, v/v), flow rate of 2.0 mL/min, automated backpressure regulator(ABPR) of 13.79 MPa, column temperature of 30 ℃ and methanol 1% formic acid(FA)(v/v) of as assisted solvent with 0.20 mL/min. And samples were constanted volume to 1mL after extracted by acetonitrile/water, dissolved by acetonitrile, eluted by acetonitrile and respectively purified by TPT or PestiCarb SPE columns, then analyzed by UPC~2-QTOF/MS with extracting characteristic ions, and quantitated by matrix external standard method. The results showed that in the concentration of 0.01 mg/L~1.00 mg/L range,standard curves are with linear relationship, and the correlation coefficients above 0.98. The recoveries of enantiomers of four chiral compounds at three spiked levels of 0.005, 0.025,0.25 mg/kg in matrix of apple and grape within the range of 63.3%~101.9%, the relative standard deviations(RSD)(n=6) were between 1.4% and 9.9%, and the limits of quantitation(LOQ) of enantiomers were below 0. 005 mg /kg. The recoveries of enantiomers of four chiral compounds at three spiked levels of 0.01, 0.05, 0.5 mg/kg in black tea were in the range of 63.9%~90.2%, the relative standard deviations(RSD)(n=6) were from 2.7% to9.7%, the limits of quantitation(LOQ) for these enantiomers were 0. 01 mg/kg. The method is quick, convenient and reliable, and could meet the requirement of residue analysis.