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Ma F.,Chinese Academy of Agricultural Sciences | Ma F.,Key Laboratory of Biology and Genetic Improvement of Oil Crops | Ma F.,Key Laboratory of Detection for Mycotoxins | Ma F.,Quality Inspection and Test Center for Oilseeds Products | And 12 more authors.
Journal of Separation Science | Year: 2012

In this paper, ultrasonic-assisted extraction of 3-chloropropane-1,2-diol and its esters from edible oils was studied with isotope dilution GC-MS. Effects of several experimental parameters, such as types and concentrations of extracting solvent, ratios of liquid to material, extraction temperature, time of ultrasonic treatment on the extraction efficiency of 3-chloropropane-1,2-diol and its esters from edible oils and sample preparation for calibration were compared and optimized. The optimal extraction conditions were suggested as 66 mg oil sample in mixture of 0.5 mL MTBE/ethyl acetate (20% v/v) and 0.5 mL of sulfuric acid/n-propanol (0.3% v/v), being extracted for 30 min at 45°C under ultrasonic irradiation. Good linearity was gained in the range of 0.020-5.000 μg/g with the limit of detection (LOD) of 0.006 μg/g (S/N = 3) and the limit of quantification (LOQ) of 0.020 μg/g (S/N = 10). The recoveries at five spiked concentrations were ranged from 91.9 to 109.3% with RSD less than 9.4%. The method was successfully applied to the determination of 3-chloropropane-1,2-diol and its esters amounts in rapeseed, sesame, peanut, camellia, and soybean oils. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


Zhang D.,Northwest University, China | Li P.,Chinese Academy of Agricultural Sciences | Li P.,Key Laboratory of Biology and Genetic Improvement of Oil Crops | Li P.,Key Laboratory of Detection for Mycotoxins | And 10 more authors.
Sensors and Actuators, B: Chemical | Year: 2013

Recent trend toward semiquantitative strip tests has been driven by a strong demand for rapid screening of toxic or harmful substances in food. Here, a detector-free semiquantitative immunochromatographic assay (ICA) has been developed. In the assay, the test zone is formed by dispensing three test lines [TLs (TL-I, TL-II and TL-III)] with the same capture reagent onto a nitrocellulose membrane. The competition between the migrating analyte and the immobilized capture reagent on three TLs for the limited number of antibody binding sites causes less nanogold-Ab probe to accumulate on TLs, which provides an easily visible color owing to the red color itself. When analyte concentration is up to the threshold level, no color appears on the TL. That's to say, the appearing number of color bands after a reaction indicates the content (range) of analyte. Analyte concentration levels can thus be determined by observing the number of TLs developed in the test zone. Taking major aflatoxins as target analytes, the threshold levels for TL-I-III and the visual detection limit of the detector-free semiquantitative strip (DFQ-strip) assay were determined, respectively. Results show that the DFQ-strip assay is superior to traditional ICAs because it offers multiple dynamic detection ranges and semiquantitative analytical capability. © 2013 Elsevier B.V. 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


Wang Y.,Chinese Academy of Agricultural Sciences | Wang Y.,Key Laboratory of Biology and Genetic Improvement of Oil Crops | Wang Y.,Key Laboratory of Detection for Mycotoxins | Wang Y.,Laboratory of Risk Assessment for Oilseeds Products | And 12 more authors.
Analytical Chemistry | Year: 2013

Anti-idiotypic antibodies recognize the antigenic determinants of an antibody, thus they can be used as surrogate antigens. Single-domain antibodies from camlid heavy-chain antibodies with the benefit features of small size, thermostability, and ease in expression, are leading candidates to produce anti-idiotypic antibodies. In this work, we constructed an antibody phage library from the mRNA of an alpaca immunized with an antiaflatoxin monoclonal antibody (mAb) 1C11. Three anti-idiotypic VHH antibodies were isolated and applied to immunoassay toward aflatoxin as a coating antigen. The best immunoassay developed with one of these VHH antibodies shows an IC50 of 0.16 ng/mL toward aflatoxin B1 and cross-reactivity toward aflatoxin B2, G1, and G2 of 90.4%, 54.4%, and 37.7%, respectively. The VHH-based immunoassay was successfully applied to the analysis of peanuts, corn, and rice, which are the predominant commodities regularly contaminated by aflatoxins. A good correlation (r2 = 0.89) was found between the data obtained from the conventional ELISA and the ELISA based on a VHH coating antigen for the analysis of aflatoxins in peanuts and feedstuff. The use of biotechnology in developing the surrogate, the absence of standard aflatoxin and organic solvents in the synthesis procedures, and the reproducibility of the VHH antibody makes it an ideal strategy for replacing conventional synthesized antigens. © 2013 American Chemical Society. Source


Wang Y.,Chinese Academy of Agricultural Sciences | Wang Y.,Northwest Agriculture and Forestry University | Li P.,Chinese Academy of Agricultural Sciences | Li P.,Key Laboratory of Biology and Genetic Improvement of Oil Crops | And 12 more authors.
Analytical and Bioanalytical Chemistry | Year: 2016

A toxin-free enzyme-linked immunosorbent assay (ELISA) for aflatoxins was developed using an anti-idiotype nanobody VHH 2–5 as surrogate standard. Anti-idiotype nanobody VHH 2–5 was generated by immunizing an alpaca with anti-aflatoxin monoclonal antibody 1C11. This assay was used to detect aflatoxins in agro-products after a simple extraction with 75 % methanol/H2O. Aflatoxin concentration was calculated by a two-step approach: the concentration of VHH 2–5 was first obtained by a four-parameter logistic regression from the detected absorbance value at 450 nm, and then converted to aflatoxin concentration by a linear equation. The assay exhibits a limit of detection (LOD) of 0.015 ng mL−1, which is better than or comparable with conventional immunoassays. The performance of our VHH surrogate-based ELISA was further validated with a high-performance liquid chromatography (HPLC) method for total aflatoxins determination in 20 naturally contaminated peanut samples, displaying a good correlation (R2 = 0.988). In conclusion, the proposed assay represents a first example applying an anti-idiotype VHH antibody as a standard surrogate in ELISA. With the advantages of high stability and ease of production, the VHH antibody-based standard surrogate can be extended in the future to immunoassays for other highly toxic compounds. [Figure not available: see fulltext.] © 2016 Springer-Verlag Berlin Heidelberg Source

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