title: Development of an improved method to extract pesticide residues in foods using acetonitrile with magnesium sulfate and chloroform.
abstract: A multiresidue method was developed based on extraction of 10 g sample with 10 mL acetonitrile and subsequent liquid-liquid partitioning formed by adding 4 g MgSO₄ plus 1 mL chloroform. During the partitioning process, the extraction recoveries of polar analytes were found to be essentially determined by the acetonitrile content in the aqueous phase. The use of MgSO₄ gave the least acetonitrile left in the aqueous phase (lower than 5%) and thus promoting complete partitioning of analytes into the organic phase. At the same time, removal of water from the acetonitrile phase was achieved by adding only a small amount of chloroform with no influence on the acetonitrile content in the aqueous phase, thus leading to decreasing the co-extraction of polar matrix components. The most complete mutual separation of acetonitrile and water was achieved by the joint use of MgSO₄ and chloroform and thus the optimal extraction recovery and analytical selectivity were obtained simultaneously. The new method, with higher recoveries of polar analytes, better analytical selectivity and simpler manipulation, is a claimed improvement to the original QuEChERS method. The proposed method was finally validated by the determination of 20 pesticides in a mixed food matrix by using liquid chromatography tandem mass spectrum (LC-MS/MS). Acceptable linearity, sensitivity, recovery, precision and selectivity results were obtained.
authors.affiliation: Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research, Ministry of Education, Hunan Normal University, Changsha 410081, China.
authors.forename: Guozhu
authors.initials: G
authors.lastname: Liu
authors.forename: Lei
authors.initials: L
authors.lastname: Rong
authors.forename: Bin
authors.initials: B
authors.lastname: Guo
authors.forename: Mingshan
authors.initials: M
authors.lastname: Zhang
authors.forename: Shengjun
authors.initials: S
authors.lastname: Li
authors.forename: Qing
authors.initials: Q
authors.lastname: Wu
authors.forename: Jitao
authors.initials: J
authors.lastname: Chen
authors.forename: Bo
authors.initials: B
authors.lastname: Chen
authors.forename: Shouzhuo
authors.initials: S
authors.lastname: Yao
mesh_terms: D000097:Acetonitriles / Q000737:chemistry*; D002725:Chloroform / Q000737:chemistry*; D002849:Chromatography, Gas; D005504:Food Analysis / Q000379:methods*; D008278:Magnesium Sulfate / Q000737:chemistry*; D010573:Pesticide Residues / Q000032:analysis* / Q000737:chemistry*; D053719:Tandem Mass Spectrometry
chemical_list: D000097:Acetonitriles; D010573:Pesticide Residues; D008278:Magnesium Sulfate; D002725:Chloroform; C032159:acetonitrile