title: Study of a molecularly imprinted solid-phase extraction coupled with high-performance liquid chromatography for simultaneous determination of trace trichlorfon and monocrotophos residues in vegetables.
abstract: BACKGROUND
  Organophosphate pesticide residues are harmful to human health because of their potential mutagenic and carcinogenic properties. Therefore, it is of great importance to development an accurate and reliable analytical method to prevent their uncontrolled effects on environmental pollution and human health.
  
  
  RESULTS
  This study reports a new method of molecularly imprinted solid-phase extraction coupled with high-performance liquid chromatography (MISPE-HPLC) for simultaneous determination of two organophosphate pesticides residues. Two types of molecularly imprinted polymers (MIPs) were prepared using the trichlorfon and monocrotophos as the template molecule, respectively, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker. The recognition ability and adsorption-desorption dynamic of each imprinted polymer toward the trichlorfon or monocrotophos were characterised. Using the mixture of trichlorfon-MIP and monocrotophos-MIP (20:80, wt/wt) as solid-phase extraction sorbent, the factors affecting the pre-concentration on the analytes and the sensitivity of the MISPE-HPLC method were optimised. Under optimal condition, the linear range was 0.005-1.0 mg L⁻¹. The limit of detection was 4.2 µg g⁻¹ for trichlorfon, and 1.2 ng g⁻¹ for monocrotophos. The peak area precision [Relative standard deviation (RSD)] for three replicates was 2.9-4.5%. The blank rape and cauliflower samples spiked with trichlorfon and monocrotophos at 0.05 and 0.005 µg g⁻¹ levels were extracted and determined by this method with recoveries ranging from 88.5% to 94.2%. Moreover, this method was successfully applied to the quantitative detection of the trichlorfon and monocrotophos residues in leek samples.
  
  
  CONCLUSIONS
  With good properties of high sensitivity, simple pre-treatment and low cost, this MISPE-HPLC method could provide a new tool for the rapid determination of multi-pesticide residues in the complicated food samples.
authors.affiliation: College of Food Science and Engineering, Shandong Agricultural University, Tai'an, 271018, P.R. China.
authors.forename: Xilong
authors.initials: X
authors.lastname: Wang
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Tang
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Wang
authors.forename: Xuguang
authors.initials: X
authors.lastname: Qiao
authors.forename: Zhixiang
authors.initials: Z
authors.lastname: Xu
mesh_terms: D001937:Brassica / Q000737:chemistry; D029741:Brassica rapa / Q000737:chemistry; D002274:Carcinogens, Environmental / Q000032:analysis; D002681:China; D002851:Chromatography, High Pressure Liquid; D005506:Food Contamination; D005513:Food Inspection / Q000379:methods*; D007306:Insecticides / Q000032:analysis*; D057230:Limit of Detection; D054802:Molecular Imprinting; D008999:Monocrotophos / Q000032:analysis*; D009153:Mutagens / Q000032:analysis; D019697:Onions / Q000737:chemistry; D010573:Pesticide Residues / Q000032:analysis*; D015203:Reproducibility of Results; D052616:Solid Phase Extraction; D014236:Trichlorfon / Q000032:analysis*; D014675:Vegetables / Q000737:chemistry*
chemical_list: D002274:Carcinogens, Environmental; D007306:Insecticides; D009153:Mutagens; D010573:Pesticide Residues; D008999:Monocrotophos; D014236:Trichlorfon
keywords: high-performance liquid chromatography; molecular imprinting; monocrotophos; solid-phase extraction; trichlorfon