Rapid latex agglutination inhibition reaction test for morphine in urine

A simple and rapid immunoassay of morphine based on latex agglutination inhibition reaction has been developed. Morphine-6-succinate is a morphine derivative, and its bovine serum albumin (BSA) conjugates were synthesized and characterized. The hapten density in the conjugate was determined spectroscopically to be 8.2 mol per mol of BSA. It was found that morphine-6-succinyl-BSA (M-6-S-BSA) exhibits favourable features in terms of immunogenicity and immunochemical specificity. A latex agglutination inhibition reaction test (LAIRT) using DEAE-cellulose purified rabbit IgG against M-6-S-BSA was found to give a sensitivity of 300 ng/ml of morphine. Various commonly used drugs and narcotics at concentration 0.1 mg/ml or less did not interfere with the test. Interference by normal urine was observed, but it could be eliminated by the inclusion of 0.78% normal rabbit serum. The sensitized latex was stable at 4°C for at least nine months. It was also stable to lyophilization and to at least four cycles of freezing and thawing. The total test time was 5 min. Comparison was made between LAIRT and enzyme-multiplied immunoassay (EMIT) on 100 urine samples collected from persons visiting the government narcotic clinic (Reference Laboratory, Tehran, Iran). While EMIT showed 84 positives and 16 negatives, LAIRT gave 68 positives and 32 negatives. The two tests showed no statistically significant difference (P < 0.05).