Colloidal gold immunochromatography test strip for detecting benzoic acid in liquid food

The invention belongs to the technical field of immunology, and relates to a colloidal gold immunochromatography test strip for detecting benzoic acid in liquid food, in particular to the influence of colloidal gold particle size on lateral flow chromatography immunoassay sensitivity. According to the method, benzoic acid is taken as a model molecule, colloidal gold with different nano-particle sizes is synthesized by adopting gradient citric acid addition and a reduction method and is taken as a gold-labeled probe, gold-labeled antibodies with different nano-particle sizes are prepared, and a system compares the influence of the colloidal gold with different nano-particle sizes on lateral flow chromatography; and a basis is provided for improving the sensitivity of lateral flow chromatography and detecting benzoic acid. The test strip is high in sensitivity and can be used for rapidly detecting colloidal gold of benzoic acid residues in liquid food, especially milk, the cut-off value is 4 mg/kg, and the dete