Abstract: An improved immunoassay for methadone is disclosed. The subject radioimmunoassay utilizes a novel antigen, antibody and novel labelled methadone derivatives.

Abstract: Aminoaryl esters and amino-lower alkyl amides of carboxy substituted barbiturates are linked via an amide linkage to carboxylated latex polymers to form reagents which are useful in a sensitive diagnostic test to detect the presence of barbiturates in body fluids.The large increase in the abuse of therapeutic agents, particularly the barbiturates, by the general population as well as military personnel, has brought with it a substantial need to improve analytical techniques for the determination of such agents in biological fluids. In many instances, medical treatment centers are faced with the immediate need for determining the identity of a barbiturate taken by a patient who is unable, being in a comatose condition, or unwilling to supply such information to the treating physician. Early procedures involved the identification of barbiturates by extraction and thin-layer, gas chromatographic and spectrophotometric methods.