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Qi P.,Zhejiang Academy of Agricultural Sciences | Qi P.,State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control | Wang X.,Zhejiang Academy of Agricultural Sciences | Wang X.,Agricultural Ministry Key Laboratory for Pesticide Residue Detection | And 8 more authors.
Journal of Separation Science | Year: 2014

The computer-assisted design and synthesis of molecularly imprinted polymers for the simultaneous capture of six carbamate pesticides from environmental water are reported in this work. The quantum mechanical computational approach was employed to design the molecularly imprinted polymers with carbofuran as template. The interaction energies between the template molecule and different functionalmonomers in various solvents were calculated to assist in the selection of the functional monomer and porogen. The optimised molecularly imprinted polymer was subsequently used as a class-selective sorbent in solid-phase extraction for pre-concentration and determination of carbamates from environmental water. The parameters influencing the extraction efficiency of the molecularly imprinted solid-phase extraction procedure were systematically investigated to facilitate the class-selective extraction. For the proposed method, linearity was observed over the range of 2-500 ng/mL with the correlation coefficient ranging from 0.9760 to 1.000. The limits of detection ranged from 0.2 to 1.2 ng/mL, and the limit of quantification was 4 ng/mL. These results confirm that computer-assisted design is an effective evaluation tool for molecularly imprinted polymers synthesis, and thatmolecularly imprinted solid-phase extraction can be applied to the simultaneous analysis of carbamates in environmental water. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA. Source


Qi P.,Zhejiang Academy of Agricultural Sciences | Qi P.,State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control | Wang Z.,Zhejiang Academy of Agricultural Sciences | Wang Z.,State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control | And 12 more authors.
Microchimica Acta | Year: 2015

The authors describe magnetite (Fe3O4) nanoparticles modified with 3-(N,N-diethylamino) propyltrimethoxysilane (Fe3O4-PSA NPs) for use as a sorbent for dispersive solid phase extraction of pesticide residues. The Fe3O4-PSA NPs were prepared by silanizing Fe3O4 NPs and modifying them with 3-(N,N-diethylamino) propyltrimethoxysilane. Field-emission scanning electron microscopy, FTIR and zeta potential measurements were employed to characterize the modified NPs. They were then used as an adsorbent to remove acidic interferences (such as malic acid and succinic acid), which are major interferences in LC-MS/MS analysis in causing ion suppression in the MS spectra of pesticides. In addition, graphitized carbon black (GCB) was used as an adsorbent to eliminate interferences by pigments. The use of Fe3O4-PSA NPs can replace time-consuming centrifugation as used in the so-called QuEChERS (quick, easy, cheap, effective, rugged and safe) method. This improvement is particularly significant in high-throughput analysis. Following the optimization of the quantities of Fe3O4-PSA NPs and GCB, the method was applied to the determination of 56 pesticides in (spiked) fruits (apple, kiwi, orange and pear) by ultra-HPLC-MS/MS. The analytical ranges typically extend from 1 to 200 ng∙mL−1, and recoveries range from 60.2 to 130 % at different concentrations of all four kinds of fruits. The LOQs for the pesticides are 10 ng∙kg−1, which makes the method a viable tool for pesticide monitoring in fruits. [Figure not available: see fulltext.] © 2015, Springer-Verlag Wien. Source


Qi P.,Zhejiang Academy of Agricultural Sciences | Qi P.,State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control | Qi P.,Agricultural Ministry Key Laboratory for Pesticide Residue Detection | Qi P.,Key Laboratory of Detection for Pesticide Residues and Control of Zhejiang | And 16 more authors.
Food Analytical Methods | Year: 2014

The enantioseparation and determination of isocarbophos enantiomers in orange pulp, peel, and kumquat by chiral HPLC tandem mass spectrometry (HPLC-MS/MS) are presented. Four cellulose-based chiral columns and two amylose-based columns were employed to explore the influence of chiral stationary phase on the enantioseparation selectivity and elution order of isocarbophos enantiomers. The fastest baseline enantioseparation of isocarbophos was achieved on amylose tris(3,5-dimethylphenylcarbamate) (Chiralpak AD-3R) with acetonitrile and water (containing 2 mmol L−1 ammonium formate and 0.1 % formic acid) (60:40, v/v) as mobile phase. The influence of temperature on enantioseparation of isocarbophos was investigated, indicating that the enantioseparation of isocarbophos on Chiralpak AD-3R columns was an enthalpy-driven separation. The method performance including linearity, sensitivity, matrix effect, and precision was evaluated. Under the optimized conditions, the recoveries of the isocarbophos enantiomers in orange pulp, peel, and kumquat were 76.1–95.4 % with RSD lower than 11.1 % at 5, 50, and 250 μg kg−1 levels. The limits of detection ranged from 0.2 to 0.5 μg kg−1 for enantiomers in orange pulp, peel, and kumquat. Application of the proposed method to the real sample analysis suggested its potential use in the enantioselective determination of isocarbophos in food samples. © 2014, Springer Science+Business Media New York. Source

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