one step DOA Screening Tests are lateral flow,one-step,qualitative ,competitive inhibition immunoassays.The tests are based on the principle of the highly specific immunochemical reactions of antigens and antibodies.The test systems employ unique monoclonal antibodies to selectively identify specific drug of abuse and the corresponding metabolites in urine samples with a high degree of sensitivity.The cut off concentration for specific drug of abuse and its metabolites has been developed at the concentration standard set by NIDA(the National Institute on Drug Abuse)for the qualitative detection of corresponding drug in human urine.