Transferrin (TF) rapid test is a double antibody sandwich immunoassay kit for the qualitative testing of TF in feces. The membrane was precoated with TF specificity antibodies on the test band region and Goat anti-mouse IgG antibody on the control band region. During the test, the specimen is allowed to react with matched TF Specific antibodies -colloid gold conjugate, which was predried on the test strip. The conjugate binds to the TF forming an antibody-antigen complex. The complex moves forward on the membrane by the capillary action, then the complex is captured by TF Specific antibodies on the test region to produce a visual red color band. Regardless of the presence of TF, as the mixture continues to move across the membrane to the control band region, the complex is captured by immobilized Goat anti-mouse IgG antibodies to form a distinct red colored control band. The quality control line (C line) should have a red line when testing samples, indicating that reagent testing is normal.