| Tea is directly soaking dringking food,the quality has closely linked with human's health.For limiting abuse pesticide and safeguarding the people's interests,more and more attention has been paid to this issue and many countries have established rigid maximum residue limits(MRLs) for the pesticide in tea.In recent years,there have been quite a few reports concerning the residue analysis of pesticides in tea.However,they are time-consuming,cost a lot of organic solvents, and have a low efficiency in the extraction of residues,In this article,we systematically studied the determination methods of pesticide residues in tea,using chromatography technology,The main results of the study are as follows:1.An efficient and sensitive method for simultaneous determination of eighteen organochlorine and nine pyrethroid pesticides in tea of Jiangxi Province has been established and validated.Pesticide residues were extracted from tea samples with hexane-dichloromethane(1:1,v/v),using Ultrasonic extraction(UE),Extracts were cleaned-up by alumina neutral-florisil column,and determined by gas chromatography equipped with electron-capture detector(GC-ECD),using DB-1701 capillary column.The recoveries of organochlorine pesticides obtained from samples spiked with standards at the concentration levels of 0.04 ug/mLand 0.01 ug/mL were in the ranges of 89.5%～118.2%and 80.0%～112.7%,with the RSD in the ranges of 3.82%～9.64%and 4.26%～11.78%,respectively.The recoveries of pyrethroid pesticides obtained from samples spiked with standards at the concentration levels of 0.20 ug/mL and 0.05 ug/mL were in the ranges of 97.5%～129.6%and 87.3%～110.1%, with the RSD in the ranges of 3.78%～10.72%and 3.02%～13.84%,respectively.The quantification limits of the organochlorine pesticides were in the range of 0.0004～0.001 ug/mL,and the pyrethroids were in the range of 0.0025～0.0050 ug/mL. The satisfactory results were obtained in the determination of organochlorines and pyrethroids in teas of Jiangxi Province.2.A new method for multiresidue analysis of organochlorines and pyrethroids in teas of Jiangxi province is proposed.Pesticide residues were extracted from tea samples with hexane—dichloromethane(1:2,v/v),using microwave-assisted extraction.In this work,the MAE extraction conditions,such as the extraction solvent type,volume,microwave heating time and microwave temperature, optimized by a three level orthogonal array design.Extracts were cleaned-up by alumina neutral-florisil column,and determined by gas chromatography equipped with electron-capture detector(GC-ECD),using DB-1701 capillary column.The recoveries obtained from Chinese tea samples(n=5) spiked with standards at the three concentration levels of 0.4 mL,0.2 mL and 0.1 mL(0.2 ug/mL organochlorines +1.0 ug/mL pyrethroids) were in the ranges of 80.9%～118.5%,88.4%～120.7%and 80.9%～116.3%,with the RSD in the ranges of 1.61%～6.70%,1.89%～6.49%and 1.98%～11.87%,respectively.A satisfactory result was obtained in the determination of pesticides residues in tea of Jiangxi province.3.A new method for multiresidue analysis of 22 organochlorines,pyrethroids, oranophosphorusin and carbamate pesticides in teas is proposed.Pesticide residues were extracted from tea samples with acetonitril-aceton(7:1,v/v).using Ultrasonic extraction(UE),In this work,the UE extraction conditions optimized by a three level orthogonal array design,such as the extraction time,extraction solvent,solvent volume,and the times of extraction.Extracts were cleaned-up by florisil and carb solid phase extraction and determined by gas chromatography equipped with MS detector(GC-MS),using HP-5 capillary column The recoveries obtained from Chinese tea samples(n=5) spiked with standards at the two concentration levels of 0.4 ug/mL and 0.1 ug/mL were in the ranges of 73.9%～113.7%and 67.3%～118.8%, with the RSD in the ranges of 1.41%～11.29%and 3.21%～11.38%,respectively.The quantification limits of the pesticides were in the range of 0.001～0.01ug/mL,A satisfactory result was obtained in the determination of organochlorines,pyrethroids, oranophosphoru and carbamate in teas of Jiangxi province.4.A method for the determination of some carbamate pesticides and their main metabolites using High Performance Liquid Chromatography(HPLC) has been developed.Pesticide residues were extracted from tea samples with acetone,then extracted from acetone with hexane-aether(1:1,v/v),Extracts were cleaned-up by Florisil-Carb solid phase extraction and determined by HPLC with ultraviolet detector.The linearity for NMC standards were good among 0.9972～0.9998,The recoveries of carbamate pesticides obtained from samples spiked with standards at the concentration levels of 1.0 ug/mL and 0.4 ug/mL,were in the ranges of 73.2%～98.0%and 75.1%～90.4%,with the RSD in the ranges of 5.59%～9.24%and 5.25%～9.73%,respectively.These results indicated that this method is simple,rapid, and sensitive for the carbamate pesticides and their main metabolites in Tea of Jiangxi province. |
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