This product uses competitive immunochromatography technology to qualitatively detect drug residues in samples. The principle is to coat the antigen with a detection line (T-line) on a nitrocellulose membrane and label the corresponding monoclonal antibody on colloidal gold. When testing, when the drug is not present in the sample to be tested, colloidal gold particles will bind to the antigen coated on the membrane when chromatography reaches the detection line position, and the T-line will show color. When the drug is present in the sample to be tested, it will bind with gold specific monoclonal antibodies to form an immune complex. When the complex is chromatography to the detection line position, it will not bind to the antigen coated on the membrane, and the T-line will not show color or become lighter.