Summary: The Ractopamine chromatographic diagnostic kit is based on the specific immuno-chemical reactions between antigen and antibody. It relies on the competition between Ractopamine residues in the sample and the Ractopamine immobilized on T line on the membrane for the Ractopamine antibody-dye conjugate. If the drug is presenting in the sample, it will compete with the drug immobilized on T line, to the limited amount of dye-antibody. When a sufficient amount of drug in the sample is presenting, the drug will saturate the antibody. Thus it will show invisible T line, indicating a positive result. If there is a negative sample (or the amount of the drug is lower than the cut-off value), it will generate two obvious lines in both the T and C line section.