Study On The Detection Technology Of Two Types Of High Risk Pesticide Adjuvants: Phthalate Acid Esters And Pyrrolidons

Pesticide adjuvants are inert chemical ingredients that are intentionally added to pesticide formulations to enhance the activity and improve stability.Most of them exhibit various levels of toxicity and some are even more harmful than the active ingredients.Compared to pesticide residues,the safety of pesticide adjuvants has not been paid enough attention.The extensive use of high risk pesticide adjuvants poses a potential threat to the safety of environment,agro-products,and human beings.Therefore,the development of simple,accurate,reliable and effective detection methods for high risk pesticide adjuvants can provide certain method references for the official release of prohibited and restricted lists of pesticide adjuvants,and it helps to enhance the management of pesticide adjuvants in China.Six phthalate esters（PAEs）including dimethyl phthalate（DMP）,diethyl phthalate（DEP）,di-n-butyl phthalate（DBP）,benzyl butyl phthalate（BBP）,di-2-ethylhexyl phthalate（DEHP）,and di-n-octyl phthalate（DnOP）,and three pyrrolidons including 2-Pyrrolidone（PYR）,N-methyl-2-pyrrolidone（NMP）,and N-ethyl-2-pyrrolidone（NEP）were selected as study objects.From the perspective of sample pretreatment technologies,three simple,effective,and accurate methods were developed for determination of pesticide adjuvants,and successfully applied in liquid pesticide formulations,water samples and plant-derived agro-products.The main contents of this research are as follows:1.In this study,samples were diluted with ethyl acetate,purified using Oasis HLB as solid-phase extraction（SPE）cartridges,and analyzed by gas chromatography–mass spectrometry（GC–MS）using the external standard method.SPE in interferences retention mode was used herein and key parameters were optimized.Moreover,the necessity for the purification step was evaluated through comparison with direct measurement of diluted samples with no cleanup procedure.The recovery experiment was performed by spiking samples including aqueous solution（AS）,emulsifiable concentrate（EC）,suspension concentrate（SC）,and emulsion in water（EW）formulations.The average recoveries ranged from 71.1 to 112.4%and RSDs were<12.0%,indicating good accuracy and precision of the developed method.The LODs were between 0.01-0.46%,which can meet the limit requirements（5%）of the three target compounds（PYR,NMP and NEP）in pesticide formulations in China.Finally,the proposed analytical method was successfully applied to 30 commercial liquid pesticides,including insecticides,herbicides,fungicides,and acaricides.Notably,NMP,PYR,and NEP were not detected in any of the samples.2.In this study,an accurate and reliable isotope-labelled internal standard method was developed and validated for simultaneous determination of three polar pesticide adjuvants,namely 2-pyrrolidone,N-methyl-2-pyrrolidone,and N-ethyl-2-pyrrolidone in plant-derived agro-products.Matrices,including apple,cabbage,tomato,cucumber,rice,and wheat,were extracted with a modified quick,easy,cheap,effective,rugged,and safe“QuEChERS”method and purified with a new clean-up sorbent（Z-Sep）.A hydrophilic interaction liquid chromatography column（HILIC）,exhibiting a lipophilic-hydrophilic character,was used to separate the three analytes over 10 min using liquid chromatography–tandem mass spectrometry（LC–MS/MS）.Matrix effects in various matrices were evaluated and an isotope-labelledinternalstandardmethodwasemployedtocompensateforion enhancement/suppression effects.At three fortification levels（2.0,5.0,and 20.0μg/kg）,the mean recoveries ranged from 78.5 to 112.1%with relative standard deviations（RSDs）<11.0%for all tested analytes.The limits of detection（LODs）and quantification（LOQs）were 0.04–0.45 and 0.12–1.58μg/kg in various matrices,respectively.The developed method exhibited both high sensitivity and satisfactory accuracy,and was successfully applied to the simultaneous determination of the three tested pesticide adjuvant residues in 6 agro-products of plant origin,including apple,cabbage,tomato,cucumber,rice,and wheat samples.3.Herein,couples of magnetic microspheres（Fe₃O₄@MIL-100 and Fe₃O₄@SiO₂@polythiophene）were prepared as mixed sorbents for the magnetic solid-phase extraction（MSPE）of six phthalate esters（PAEs）,including DMP,DEP,DBP,BBP,DEHP,and DnOP in liquid pesticide fromulations and various water samples prior to gas chromatography-mass spectrometry（GC-MS）analysis.The synthetic magnetic nanocomposites exhibited good repeatability（7 times）and chemical stability as well as high extraction efficiency for the tested target analytes.The mixed sorbents substantially improved the extraction efficiency of both DMP and DEP.Several parameters,including the amount of sorbents,elute solvent,adsorption and desorption time,sample pH,and sample volume,were optimized.Under the optimal conditions,the mean recoveries ranged from 72.3%to 110.8%with relative standard deviations（RSDs）<12%.The developed method displayed high sensitivity with satisfactory accuracy and was finally successfully applied to the quantitative analysis of the 6 tested PAEs in 3 types of water samples（tap,drinking and mineral water）and 20 liquid pesticide formulations.