Study Of A Sensitive Detection Method Of Organochlorine Pesticide Residue By Multi Dimensional Gas Chromatograph-Mass Spectrometer System

Organochlorine pesticides have a long history of using to control agricultural pests all around the world.Most of them have been found harmful to the ecological environment and human health because of their potential toxicity. And the prolonged application of large scale and its persistence make these pesticides having widespread residues in environmental and biological samples, which have formed the potential risks and threat to human beings. As the complexity of sample matrix, it is necessary to establish a high selective and stable analytical technique with efficient sample pretreatment.In this research, a task-specific ionic liquid based dummy molecularly imprinted polymer with good adsorption capability and selectivity to nine organochlorine pesticides was prepared using bisphenol A as dummy template,1-(triethoxysilyl) propyl-3-aminopropyl imidazole bromide as monomer, and tetraethoxysilane as cross-linker by combining surface imprinting with a sol-gel process. With a series of optimization experiments, it was found that the imprined polymer prepared with the solvent of 2 mL tetrahydrofuran and 2 mL methanol, the amount of template molecule, functional monomer and cross-linker at 228 mg,820 mg,887μL,500μL 0.1 mol L-1 NH3·H2O as catalyst,50 mL methanol and HC1 (1.0 mol L-1) (1/1, v/v) as the elution solvent to remove the template and Soxhlet’s technique with methanol and acetic acid (9:1, v/v) to remove the template completely, had higher adsorption capacity and selective ability for the template molecule. The results of kinetic and static adsorption experiments indicated that the imprinted polymer had higher saturated adsorption capacity (30.76 mg g-1) to the template and fast mass transfer rate (the adsorption equilibrium was achieved in 60 min).A method was developed with this molecularly imprinted polymer as solid-phase extraction sorbent coupling with multi dimensional gas chromatograph-mass spectrometer for the enrichment and detection of organochlorine pesticides in environment and food samples. Under the optimum conditions, good linearity was obtained for each analyte (R2>0.99), the limits of detection (S/N=3) of the method ranged from 0.007-0.126 μg L-1, and relative standard deviation for nine parallel determinations were below 6.69%.To evaluate the applicability of the developed method, free samples of river water, rural water, rural soil, rice and tea leaf were spiked and analyzed. The concentrations of nine organochlorine pesticides in free samples ranged from 0.0150-2.0787 μg L-1/μg kg-1. Recoveries of the spiked samples (two water samples were spiked with 0.5μg L-1 and 1.0 μg L-1, and other samples were spiked with 5.0 μg kg-1 and 10.0 μg kg-1) were achieved ranging from 65.65%-129.61% with satisfied relative standard deviation (RSD) of 0.91 %-11.47%.