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Li C.,Hebei University of Engineering | Wu Y.L.,Ningbo Agriculture Products Quality Detector Center | Shen J.Z.,China Agricultural University
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment | Year: 2010

An analytical method for the simultaneous determination of Sudan dyes (Sudan Red G, Sudan I, Sudan II, Sudan III, Sudan Red 7B and Sudan IV) and Para Red in food by ultra-performance liquid chromatography-electrospray tandem mass spectrometry (UPLC-ESI-MS/MS) was developed. Samples were extracted with acetonitrile, and water added into the extract. The supernatant was analysed by UPLC-MS/MS after refrigeration and centrifugation. The sample was separated on an Acquity BEH C18 column, and detected by MS/MS with the multiple reaction monitoring mode. Matrix calibration was used for quantitative testing of the method. The linear matrix calibrations of Sudan dyes and Para Red were 2-50 and 10-250 ng g-1, respectively, and the regression coefficients were >0.9945. The recoveries were 83.4-112.3% with good coefficients of variation of 2.0-10.8%. The limits of detection were between 0.3 and 1.4 ng g-1 for the six Sudan dyes, and between 3.7 and 6.0 ng g-1 for Para Red. The limits of quantification were between 0.9 and 4.8 ng g-1 for the six Sudan dyes, and between 12.2 and 19.8 ng g-1 for Para Red. © 2010 Taylor & Francis. Source


Li C.,Hebei University of Engineering | Wu Y.-L.,Ningbo Agriculture Products Quality Detector Center | Yang T.,Ningbo Agriculture Products Quality Detector Center | Zhang Y.,Ningbo Agriculture Products Quality Detector Center
Chromatographia | Year: 2011

A rapid, sensitive and reliable LC-MS-MS method for the determination of eight benzimidazoles in animal feed was developed and validated. Samples were extracted with acidic acetonitrile. The extract was diluted with 0.1% formic acid in water, and analyzed by LC-MS-MS on a Waters XBridge™ C 18 column with acetonitrile/0.1% formic acid in water as mobile phase. The samples were quantified with the matrix standard calibration curve method. Good linearity was obtained for eight benzimidazoles at a concentration of 0.005-2.5 μg mL-1 with a linear relative coefficient more than 0.990. Recoveries of 84.0-104.0% with CVs of 2.50-7.50% were obtained. Limit of detection was 2.1-63.0 μg kg-1. The method demonstrated to be suitable for the determination of eight benzimidazoles in animal feed samples. © 2011 Springer-Verlag. Source


Li C.,Hebei University of Engineering | Wu Y.-L.,Ningbo Agriculture Products Quality Detector Center | Yang T.,Ningbo Agriculture Products Quality Detector Center | Zhang Y.,Ningbo Agriculture Products Quality Detector Center
Chromatographia | Year: 2010

A simple, rapid, sensitive and reliable analytical method for the determination of metaldehyde in water by ultra performance liquid chromatography-electrospray tandem mass spectrometry (UPLC-ESI-MS-MS) was developed. Water samples were directly purified on C18 cartridge. Then metaldehyde was eluted using 2 mL of methanol/water (85:15 v/v) and directly analyzed by UPLC-MS-MS on an Acquity BHE C18 column with methanol/20 mM ammonium acetate solution (85:15 v/v) as mobile phase. The samples were quantified with the external standard calibration curve method. Good linearity was obtained for metaldehyde at a concentration of 0.05-5 ng mL-1 with a linear relative coefficient >0.999. Recoveries of 96.1-106.3% with CVs of 2.61-4.77% were obtained. Limit of detection was 0.003 ng mL-1. The method demonstrated to be suitable for the determination of metaldehyde in water samples. © 2010 Vieweg+Teubner Verlag | Springer Fachmedien Wiesbaden GmbH. Source


Li C.,Hebei University of Engineering | Wu Y.,Ningbo Agriculture Products Quality Detector Center | Yang T.,Ningbo Agriculture Products Quality Detector Center | Zhang Y.,Ningbo Agriculture Products Quality Detector Center
Journal of Chromatography A | Year: 2010

A simple, sensitive and reliable analytical method for the rapid simultaneous determination of dexamethasone and betamethasone in milk by high performance liquid chromatography-negative electrospray ionization tandem mass spectrometry (HPLC-NESI-MS/MS) with isotope dilution was developed. Samples were directly purified through C18 cartridge. Then the eluate was dried under nitrogen and residues were dissolved in mobile phase. Samples were analyzed by HPLC-MS/MS on a Hypercarb graphite column with a mixture of acetonitrile-water-formic acid as mobile phase. The samples were quantified using dexamethasone-D4 as an internal standard. The procedure was validated according to the European Union regulation 2002/657/EC determining specificity, decision limit (CCα), detection capability (CCβ), trueness, precision, linearity and stability. The method is demonstrated to be suitable for the determination of dexamethasone and betamethasone in milk. The total time required for the analysis of one sample was about 35 min. © 2009 Elsevier B.V. All rights reserved. Source


Yang T.,Ningbo Agriculture Products Quality Detector Center | Huangfu W.G.,Ningbo Agriculture Products Quality Detector Center | Wu Y.L.,Ningbo Agriculture Products Quality Detector Center
Poultry Science | Year: 2011

An experiment was carried out to determine melamine residual levels in eggs by feeding laying hens 200 or 1,000 mg of melamine/kg of diet. Each diet was offered in 3 replicate cages (10 laying hens/ cage) from d 1 to 29, followed by a 9-d feeding of a withdrawal diet that contained no melamine. Two eggs were collected from each replicate cage each day for the determination of residual melamine levels after 1 d of feeding. The feeding of melamine resulted in a fast accumulation of melamine in eggs within 3 to 4 d, then maintained 2.00 to 3.88 mg/kg for 200 mg of melamine/ kg of diet and 11.09 to 16.46 mg/kg for 1,000 mg of melamine/kg of diet. A withdrawal period of 4.0 d for 1,000 mg of melamine/kg of diet was required based on tolerance values established by the World Health Organization and no withdrawal period was required for 200 mg of melamine/kg of diet. © 2011 Poultry Science Association Inc. Source

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