Tetracycline is a broad-spectrum antibiotic, mainly functions in inhibiting bacterial protein synthesis. It is applied in treating infectious disease for livestocks with benefits like low-cost, low toxicity and great therapeutic effect. However, tetracycline residures in food has threatened human health substantially and brought social attention.

EU MRL rules the combined total residues of all substances within the Tetracycline group in milk should not exceed 100 ppb.

Drug residues test of Tetracycline applies the principle of competition-inhibition immunochromatography. Tetracycline in the sample binds to specific monocolonal antibodies labeled by colloidal gold, which prevents antibodies from binding to haptens immobilized on test line. Therefore, uncolored test line indicates a positive result.