| As an important food and drug dual-use product,it is widely used as a food supplement in the daily life by some consumers.However,there is no detection method for multi-pesticide residues in various chrysanthemum samples in China and abroad.At the same time,there are few pesticides registered in chrysanthemums in China and the maximum limit standard is missing.Therefore,the establishment of accurate and convenient pesticide residue analytical method was the basis for the high efficient monitoring of pesticide residue in chrysanthemum.This study is based on the characteristics of chrysanthemum which is rich in active substances,using the amino modified multi-walled carbon nanotubes(MWCNTs-NH2)as a main adsorbent material in the dispersive solid phase extraction process to improve the traditional Qu ECh ERS(quick,easy,cheap,Efficient,rugged and safe)method to establish a pre-treatment method;Using supercritical fluid chromatography-triple quadrupole mass spectrometry(SFC-MS/MS)as an analytical instrument to improve the matrix effect.The present work purpose to develop an efficient pesticides residue analytical method in chrysanthemum based on the optimization of sample preparation and instrumental analytical methods.After systematically analyzing and verifying the feasibility of the method,it was applied to the actual sample analysis to evaluate the dietary intake risk of pesticides detected in Zhejiang Chrysanthemum.The main findings are as follows:1.A pretreatment method for multiple pesticide residues in various chrysanthemums is established which is based on the traditional Qu ECh ERS method.By simulated adsorption experiments,the adsorption capacity of six different MWCNTs on 112 pesticides was compared,and 10 mg MWCNTs-NH2 and 10 mg C18 were selected as purification adsorbents for Qu ECh ERS.A modified Qu ECh ERS method was used to establish a method for the determination of 112 pesticide residues in seven chrysanthemum samples with SFC-MS/MS.112 pesticides were selected,10 m L acetonitrile was used as the extraction solvent,and MWCNTs-NH2 and C18 were all 10 mg.After extraction and purification,they were anal yzed by SFC-MS/MS.Method validation was further carried out to verify the linearity,sensitivity,recovery and precision of the developed method.Good linearity was found for 92 % of analytes in the concentration range of 2-250 ?g·L-1 in all the seven chrysanthemum samples with the correlation coefficient(R2)higher than 0.99.However,nine pesticides were not fitted owing to their low responses,including aldicarb,sulfonecarbaryl,chlordimeform,dimethyl phthalate,etrimfos,isocarbophos,sulfotep,terbufos and tolclofos-methyl.The LODs of 112 pesticides ranged from 0.01 to 31.41 ?g L-1 in various samples.The mean recoveries of all the pesticides were 96,91 and 89 %,The mean RSD were 11,12 and 15 % at the spiked concentration of 20,50 and 200 ?g kg-1.These results clearly demonstrated the applicabilit y of the developed method for si multaneous determination of 112 pesticides in various chrysanthemum samples.2.Improving the matrix effect problem with SFC-MS/MS.Seven chrysanthemum samples were analyzed by SFC-MS/MS and liquid chromatography-triple quadrupole mass spectrometry(LC-MS/MS),and the signal intensities and matrix effect of 112 pesticides were analyzed and compared by two instruments.The results showed that the ratio of pesticides with superior signal intensities was 45 % and 55 % which were analyzed by SFC-MS/MS or LC-MS/MS,respectively.But there was only 9 % of the total amount of pesticides had significant difference by LC-MS/MS,so the SFC-MS/MS method and LC-MS/MS method had no significant difference in the overall signal intensities of 112 pesticides.At the same time,the matrix effect of the pesticides of the seven chrysanthemum samples analtzed by SFCMS/MS was 1.8-29 times higher than that of LC-MS/MS.In addition,the use of SFC-MS/MS can shorten the measurement time and improve the efficiency of analysis.3.Using the established method to evaluate the dietary risk intake of chrysanthemum in Zhejiang province and further verify its applicability.The pesticide residues of 29 samples of chrysanthemum morifolium were tested,and the risk of chronic dietary intake and acute dietary intake were evaluated for different batches of chrysanthemum.The results showed that the %ADI of 12 pesticides in the risk assessment of chronic dietary intake was less than 100%,the chronic risk of chrysanthemum in Zhejiang province is completely acceptable.In the acute dietary intake risk assessment,the acute intake information for boscalid,chlorantraniliprole,isoprothiolane is unnecessary to establish ARf D.Among the other 9 pesticides,the %ARf D was significantly less than 100%(0.0233~2.0049),and the acute intake risk of zhejiang chrysanthemum was acceptable.In summary,the improved Qu ECh ERS method based on MWCNTs-NH2 was combined with SFC-MS/MS to achieve rapid determination of 112 pesticides in seven chrysanthemums in this study.The method can quickly and efficiently determine the multi-pesticide residues in a variety of chrysanthemums,and significantly reduces the interference of the matrix effect in the experiment.The multi-pesticide residue analysis method currently developed can provide effective detection technology support for multi-pesticide residues in chrysanthemum,provide detailed data for pesticide using and improve food safety in chrysanthemum. |
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