T/CAICC 01-2021 Rapid detection of pyrimethanil in raw milk using colloidal gold immunochromatography method

Scope

Scope: This method specifies a rapid detection method for imidacloprid in raw milk using colloidal gold immunoassay. This method is suitable for the rapid determination of imidacloprid in raw milk; Main technical content: 3. Principle This method adopts the principle of competitive inhibition immunoassay. After extraction, imidacloprid in the sample combines with the colloidal gold-labeled specific antibody, inhibiting 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 depth of the detection line. By comparing the color depth of the detection line with that of the control line (C line), the qualitative determination of imidacloprid in the sample is made. 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 Class II water in GB/T 6682. 4.1.1 Methanol (CH3OH). 4.1.2 Reference substances: The Chinese and English names, CAS registry number, molecular formula, and relative molecular mass of the imidacloprid reference substance are shown in Table 1. The purity shall be ≥98%. Table 1: Chinese and English names, CAS registry number, molecular formula, and relative molecular mass of imidacloprid reference substances Chinese name English name CAS registry number Molecular formula Relative molecular mass Imidacloprid Imidacloprid 138261-41-3 C9H10ClN2O2 255.7 Note: Or equivalent traceable substances. 4.2 Solution preparation 4.2.1 Imidacloprid standard stock solution (100 μg/mL): Accurately weigh 1 mg of the imidacloprid reference substance (4.1.2) and place it in a 10 mL volumetric flask. Dissolve and dilute to the mark with methanol (4.1.1), shake well, and prepare a standard stock solution of imidacloprid with a concentration of 100 μg/mL. Store at 4℃ in the dark for 6 months. 4.2.2 Imidacloprid standard working solution (1 μg/mL): Precisely

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