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Xie W.,Zhejiang Entry Exit Inspection and Quarantine Bureau | Han C.,Wenzhou Entry Exit Inspection and Quarantine Bureau | Qian Y.,Zhejiang Lead Product Technic Co. | Ding H.,Zhejiang Entry Exit Inspection and Quarantine Bureau | And 2 more authors.
Journal of Chromatography A | Year: 2011

This work reports a new sensitive multi-residue liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for detection, confirmation and quantification of six neonicotinoid pesticides (dinotefuran, thiamethoxam, clothiandin, imidacloprid, acetamiprid and thiacloprid) in agricultural samples (chestnut, shallot, ginger and tea). Activated carbon and HLB solid-phase extraction cartridges were used for cleaning up the extracts. Analysis is performed by LC-MS/MS operated in the multiple reaction monitoring (MRM) mode, acquiring two specific precursor-product ion transitions per target compound. Quantification was carried by the internal standard method with D4-labeled imidacloprid. The method showed excellent linearity (R2≥0.9991) and precision (relative standard deviation, RSD≤8.6%) for all compounds. Limits of quantification (LOQs) were 0.01mgkg-1 for chestnut, shallot, ginger sample and 0.02mgkg-1 for tea sample. The average recoveries, measured at three concentrations levels (0.01mgkg-1, 0.02mgkg-1 and 0.1mgkg-1 for chestnut, shallot, ginger sample, 0.02mgkg-1, 0.04mgkg-1 and 0.2mgkg-1 for tea sample), were in the range 82.1-108.5%. The method was satisfactorily validated for the analysis of 150 agricultural samples (chestnut, shallot, ginger and tea). Imidacloprid and acetamiprid were detected at concentration levels ranging from 0.05 to 3.6mgkg-1. © 2011 Elsevier B.V. Source


Hou J.-B.,Zhejiang Academy of Science and Technology for Inspection and Quarantine | Xie W.,Zhejiang Academy of Science and Technology for Inspection and Quarantine | Li J.,Zhejiang Lead Product Technic Co. | Lu S.,Zhejiang Lead Product Technic Co. | And 2 more authors.
Journal of Chinese Mass Spectrometry Society | Year: 2016

A method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the determination of five nitrogen-rich adulterants (dicyclanil, dicyandiamide, biuret, cyromazine, melamine) in milk and powdered milk samples. These compounds were potential to be used in economic adulteration to enhance the nitrogen content in milk products. The protein of sample was precipitated, and the extracts were dissolved and distilled with acetonitrile. The supernatant solution was extracted with n-hexane to remove the fat, and then cleaned up with SPE HLB cartridges. The quantitative detection was performed on LC-MS/MS by multiple reaction monitoring (MRM) mode under positive electrospray ionization (ESI+). Isotopes dilution internal standard method (melamine) or external standard method (dicyclanil, dicyandiamide, biuret and cyromazine) was used to determine the residue contents in samples. The limits of quantification (LOQs, S/N=10) are dicyclanil (0.5 μg/kg), dicyandiamide (2.5 μg/kg), biuret (20 μg/kg), cyromazine (5 μg/kg), melamine (15 μg/kg) for milk samples and dicyclanil (8 μg/kg), dicyandiamide (35 μg/kg), biuret (50 μg/kg), cyromazine (40 μg/kg), melamine (50 μg/kg) for powered milk samples. Single-laboratory method validation data are determined, the calibration standard curves concentration are 0, 50, 100, 200, 400 μg/kg and the correlation coefficients are more than 0.991. The average recovery is 72.4%-102.8%, and the relative standard deviation (RSD) is 1.3%-12.3%. The residues of 5 compounds in 55 batches of milk and milk powder samples are determined by LC-MS/MS, and the results are consistent with the national standard method (GB/T 22388-2008). This method is suitable for determination and confirmation of these compounds and provides a convenient, rapid and effective approach to proactively combat economically motivated adulteration in milk and powdered milk sample. © 2016, Editorial Board of Journal of Chinese Mass Spectrometry Society. All right reserved. Source


Hou J.,Zhejiang Academy of Science and Technology for Inspection and Quarantine | Xie W.,Zhejiang Academy of Science and Technology for Inspection and Quarantine | Chen X.,Zhejiang Academy of Science and Technology for Inspection and Quarantine | Xi J.,Zhejiang Lead Product Technic Co. | And 3 more authors.
Chinese Journal of Chromatography (Se Pu) | Year: 2011

A method of solid phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) for simultaneous determination of 54 drug residues (sulfonamides; nitro-imidazoles, quinolones, macrolides, lincosamides and praziquantel) in honey was developed. The honey samples were diluted by phosphate buffer solution (pH 8) followed by a further cleanup procedure with an Oasis (HLB) SPE column. The detection was carried out by LC-MS/MS, using positive-ion electrospray ionization in multiple reaction monitoring (MRM) mode, with one precursor/two product ion transitions for each compound. Isotope dilution internal standard method or external standard method was used to determine the residue contents with a good linear relationship (r > 0. 992). The limits of quantification (LOQs, S/N > 10) were 1.0 μg/kg for sulfonamides and nitroimidazoles, 2.0 μg/kg for quinolones and lincosamides, 3.0 μg/kg for macrolides, and 0.3 μg/kg for praziquantel. The recovery ranges were from 32.6% to 114% with the relative standard deviations (RSDs) between 1.3% and 28.9%. As a screening method, the developed procedure is suitable for the determination and confirmation of the drug residues in honey samples. Source

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