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Wang X.,Chinese Academy of Agricultural Sciences | Wang X.,Key Laboratory of Biology and Genetic Improvement of Oil Crops | Wang X.,Laboratory of Risk Assessment for Oilseeds Products Wuhan | Li P.,Chinese Academy of Agricultural Sciences | And 3 more authors.
Food Chemistry | Year: 2015

An automated, size-exclusion solid phase extraction (SPE)-UPLC-MS/MS protocol without pre-treatment of samples was developed to screen for four mycotoxins (OTA, ZEN, AFB1, and AFM1) in liquid milk and milk powder. Firstly, a mixed macropore-silica gel cartridge was established as a size-exclusion SPE column. The proposed methodology could be a candidate in green analytical chemistry because it saves on manpower and organic solvent. Permanent post-column infusion of mycotoxin standards was used to quantify matrix effects throughout the chromatographic run. Matrix-matched calibration could effectively compensate for matrix effects, which may be caused by liquid milk or milk powder matrix. Recovery of the four mycotoxins in fortified liquid milk was in the range 89-120% and RSD 2-9%. The LOD for the four mycotoxins in liquid milk and milk powder were 0.05-2 ng L-1 and 0.25-10 ng kg-1, respectively. The LOQ for the four mycotoxins in liquid milk and milk powder were 0.1-5 ng L-1 and 0.5-25 ng kg-1, respectively. © 2014 Elsevier Ltd. All rights reserved. Source


Liu J.,Chinese Academy of Agricultural Sciences | Liu J.,Key Laboratory of Detection for Mycotoxins | Zhang Q.,Chinese Academy of Agricultural Sciences | Zhang Q.,Key Laboratory of Detection for Mycotoxins | And 12 more authors.
Food and Agricultural Immunology | Year: 2014

The glutathione-coated CdTe quantum dots (QDs) were synthesized in a paper. After purification, the QDs were coupled with monoclonal antibody to fight against fenvalerate. The conjugates had the same emission wavelength as that of QDs. The excitation wavelength and emission wavelength of the conjugates were determined to obtain the highest signal-to-noise ratio. After the antibody concentration optimization, the fluorescence-linked immunoassay method was developed. The method used the QDs as the signal to quantify the fenvalerate. Compared with the enzyme-linked immunosorbent assay (ELISA), it saved more than 1 h and decreased the false-positive rate using the specified emission wavelength of QDs. The 50% inhibitory concentration (IC50) of the method was 0.28 μg mL-1. The detection limit was 25 ng mL-1 and the linear range was 60 ng mL-1-3.83 μg mL-1. Via preliminary application, fenvalerate residues in spiked samples were determined. The recovery of fenvalerate in water samples ranged from 84.5% to 96.2% and that in vegetables ranged from 72.5% to 125.7%. It was a rapid detection of the fenvalerate residue in environment and vegetables. © 2013 Taylor & Francis. Source


Zhao F.,Chinese Academy of Agricultural Sciences | Liu J.,Chinese Academy of Agricultural Sciences | Wang X.,Chinese Academy of Agricultural Sciences | Wang X.,Key Laboratory of Detection for Mycotoxins | And 13 more authors.
European Journal of Lipid Science and Technology | Year: 2013

The method of headspace coupled with comprehensive two-dimensional GC-time-of-flight MS (HS-GC×GC-TOF/MS) was applied to differentiate the volatile flavor compounds of three types of pure vegetable oils (sesame oils, peanut oils, and soybean oils) and two types of adulterated oils (sesame oils and peanut oils adulterated with soybean oils). Thirty common volatiles, 14 particular flavors and two particular flavors were identified from the three types of pure oils, from the sesame oils, and from the soybean oils, respectively. Thirty-one potential markers (variables), which are crucial to the forming of different vegetable oil flavors, were selected from volatiles in different pure and adulterated oils, and they were analyzed using the principal component analysis (PCA) and cluster analysis (CA) approaches. The samples of three types of pure vegetable oil were completely classified using the PCA and CA. In addition, minimum adulteration levels of 5 and 10% can be differentiated in the adulteration of peanut oils and sesame oils with soybean oils, respectively. Practical applications: The objective was to develop one kind of potential differentiated method to distinguish high cost vegetable oils from lower grade and cheaper oils of poorer quality such as soybean oils. The test result in this article is satisfactory in discriminating adulterated oils from pure vegetable oils, and the test method is proved to be effective in analyzing different compounds. Furthermore, the method can also be used to detect other adulterants such as hazelnut oil and rapeseed oil. The method is an important technical support for public health against profit-driven illegal activities. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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