Technical Support

Technical Support

Principle of Amphetamine Test
Coretests, Inc.
The One Step Amphetamine Test is a one-step immunoassay in which a chemically labeled drug (drug conjugate) competes with the drug which may be present in urine for limited antibody binding sites. The test device contains a membrane strip that was pre-coated with drug conjugate on the test band. A colored anti-amphetamine monoclonal antibody colloidal gold conjugate pad is placed at the right end of the membrane. In the absence of the drug in the urine, the solution of colored antibody-colloidal gold conjugate and urine moves upward chromatographically by capillary action across the membrane. This solution then migrates to the immobilized drug-protein conjugate zone to form a visible line as the antibody complexes with the drug-protein conjugate. Therefore, the formation of a visible precipitant in the test band region occurs when the test urine is negative for the drug. When the drug is present in the urine, the drug/metabolite antigen competes with the drug-protein conjugate on the test band region for the limited antibody sites on the anti-amphetamine antibody-colloidal gold conjugate. When a sufficient concentration of the drug is present, it will fill the limited antibody binding sites. This will prevent the attachment of the colored antibody-colloidal gold conjugate to the drug-protein conjugate zone on the test band region (T). Therefore, the absence of the red band on the test region indicates a positive result.
A control band that has a different antigen/antibody reaction is added to the immunochromatographic membrane strip at the control region (c) to indicate that the test has performed properly. This control line should always appear regardless of the presence of the drug of metabolite. This means that negative urine will produce two red bands, and positive urine will produce only one band. The presence of this red band in the control region also serves as verification that 1) sufficient volume has been added, and 2) that proper flow was obtained.