Detection Of Multiple Pesticide Residues In Fruits And Vegetables Using Modified QuEChERS Method With Liquid Chromatography Tandem Mass Spectrometry

With the development of people's living standard,the consumption of fruits and vegetables is increasing.The safety problem of fruits and vegetables are getting more and more attention.Many countries have already issued the limitations of agricultural pesticide residues.In terms of more controlled pesticides and limitations of the pesticides residues in fruits and vegetables,the requirement of a highly sensitive,fast and accurate analytical method is definitely urgent.In 2003,quick,easy,cheap,effective,rugged and safe(QuEChERS)is a type of sample preparation method that was first reported by Anastassiades et al.which became more widespread in the detection of pesticide.Magnetic nanoparticles(MNPs)is a type of novel materials with special properties such as magnetic properties,surface effect and adsorption property.In the sample preparation process,magnetic nanoparticles are used to eliminate the impurities from the sample solution when it is exposed in the external magnetic field,which could save the process of centrifugation,filtration and other steps.In this paper,a method for the detection of 198 pesticide residues in fruits and vegetables was established based on a modified QuEChERS sample preparation method with MNPs as the adsorbing material and liquid chromatography–tandem mass spectrometry(LC–MS/MS).The main conclusions and results are as following:(1)14 types of typical pesticides were chosen to optimize extraction and purification conditions based on the traditional QuEChERS sample preparation process using cucumber as the sample material.MNPs were made by coprecipitation and their characterization was observed under the transmission microscope(TEM).The sample were extracted with acetonitrile/formic acid(99/1,v/v)solution,centrifuged by salting out.The purification system was consist with 50 mg of MNPs,50 mg of N-propyl ethylenediamine(PSA)and 50 mg of octadecyl(C18).Purification time is 50 s.The purification system resulted in a good purification effect and improved the efficiency of purification.(2)A method using LC-MS/MS and the electrospray ion source(ESI)for the detection of198 pesticide residues in fruits and vegetables were established under the positive and negative ion multiple reaction monitoring(MRM)mode.198 types of pesticides can be wellseparated,the linear correlation coefficient is higher than 0.995 in the range of 1~100?g/L,the limit of detection(LOD)ranged between 0.001?g/L and 0.320?g/L,the limit of quantaintion(LOQ)ranged between 0.003?g/L and 0.970?g/L.(3)Recoveries were evaluated in three representative matrices(pear,spinach and tomato)with the spiked concentrations of 5?g/kg,20?g/kg and 50?g/kg.The recoveries of 198 pesticides ranged between 67.9% and 118.5%.The relative standard deviations were less than10.58%.This method extended the application scope and applicability of the method.(4)10 types of vegetables from Weifang city market were selected and tested for safety using experimental method and the national standard GB/T 5009.218-2008 “Determination of Pesticide Residues in Fruits and Vegetables”.The results showed that the detected pesticides were basically the same.However,the experimental method is more time-saving and affordable.The results also showed that the safety of the 10 types of vegetables is satisfactory.None of the forbidden high-toxic pesticides were detected in these vegetables.The method has the advantages of quick analysis,good reproducibility and high sensitivity which is suitable for high sensitivity detection of pesticide residues in fruits and vegetables.