A Sensitive, Rapid Radioimmunoassay for Morphine and ImmunologicallyRelated Substances in Urine and Serum

A rapid, simple radioimmunoassay for morphine and immunologically related compounds is described and evaluated. The 2-h assay requires as little as 0.1 ml of urine or serum and provides a quantitative esti-mate of serum or urinary morphine. Individuals known not to be receiving heroin or other narcotics had apparent urinary morphine concentrations of less than 25 zg/liter and apparent serum concentra-tions of less than 10.tg/liter. Patients receiving as much as 100 mg of methadone gave results (ex-pressed as morphine) of less than 25 or 10 sg/liter, respectively, for their serum and urine. Fifty-eight of 59 urines from known heroin users, sampled up to 48 h after self-administered heroin, contained more than 25 ig of morphine per liter; 32 of 37 sera ob