Enzyme-linked immunosorbent assay and latex agglutination inhibition reaction test for morphine in urine

An enzyme-linked immunosorbent assay (ELISA) and a latex agglutination inhibition reaction test (LAIRT) for morphine have been established. Rabbits were immunized with 3-carboxymethylmorphine-bovine serum albumin (BSA) conjugate to obtain anti-morphine antibody and IgG fraction of the antiserum was used as an antibody. In ELISA, 3-carboxymethylmorphine-alkaline phosphatase (ALP) conjugate and antibody adsorbed on polystyrene microtiter wells were used. The enzyme activity of antibody bound ALP was measured with the enzyme cycling method. The range of morphine measurable by ELISA was 6-600 pg/well and the analysis time for 96 wells was 90 min. In LAIRT, 3-carboxymethylmorphine-rabbit serum albumin (RSA) conjugate and the antibody were bound to latex particles covalently to prepare latex-antigen and latex-antibody reagent, respectively. The agglutination reaction with latex-antigen and latex-antibody reagents was inhibited by 0.2 mu g morphine/ml urine and the analysis time for six samples on one glass slide was 20 min. The urine samples of 47 suspected abusers were analyzed by ELISA and LAIRT and the results were compared with those of the enzyme-multiplied immunoassay technique (EMIT(R)) and gas chromatography/mass spectrometry (GC/MS). Both ELISA and LAIRT for morphine seem to be suitable for the screening of urine samples.