T/CAICC 03-2021 Rapid detection of Chlorpyrifos in fruits and vegetables using colloidal gold immunochromatography method

Scope

Scope: This method specifies a rapid detection method for chlorpyrifos in vegetables and fruits using colloidal gold immunoassay. This method is applicable to the rapid determination of chlorpyrifos in vegetables and fruits such as Brussels sprouts, cowpeas, chives, and apples. Main technical content: 3. Principle: This method adopts the principle of competitive inhibition immunoassay. After extraction, the chlorpyrifos in the sample binds to the specific antibody labeled with colloidal gold, which inhibits the binding of the antibody and the antigen on the detection line (T line) of the test strip, resulting in a change in the color intensity of the detection line. By comparing the color intensity of the detection line with that of the control line (C line), the chlorpyrifos in the sample can be qualitatively determined. 4. Reagents and materials 4.1 Reagents: Unless otherwise specified, all reagents are of analytical purity, and the laboratory water should meet the requirements of Grade II water in GB/T 6682. 4.1.1 Methanol (CH3OH). 4.1.2 Extraction solution: Provided by the colloidal gold immunoassay test strip or prepared according to its instructions. 4.1.3 Reference substance: The Chinese and English names, CAS registration number, molecular formula, and relative molecular mass of the chlorpyrifos reference substance are shown in Table 1. The purity should be ≥98%. Table 1: Chinese and English names, CAS registration number, molecular formula, and relative molecular mass of the chlorpyrifos reference substance Chinese name English name CAS registration number Molecular formula Relative molecular mass Chlorpyrifos Chlorpyrifos 2921-88-2 C9H11Cl3NO3PS 350.6 Note: Equivalent traceable substances may also be used. 4.2 Solution preparation 4.2.1 Chlorpyrifos standard stock solution (100 μg/mL): Accurately weigh 1 mg of the chlorpyrifos reference substance (4.1.3) and place it in a 10 mL volumetric flask. Dissolve and dilute t

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