Stability test for the enzyme immunoassay reagents of Mitragynine

Abstract

IntroductionStability tests are used to evaluate whether an assay is suitable for general laboratory use. All reagents undergo degradation at a defined rate determined by the laws of chemistry and physics. In this assay, stability of antibodies against mitragynine, horseradish peroxidase labeled with mitragynine, and standard calibrators of mitragynine were examined. ObjectiveTo examine the stability of enzyme immunoassay reagents of mitragynine. MethodsFor stability test on antibodies and horseradish peroxidase, four types of stabilizers were used and compared with a control. The stabilizers include HRP SELECT, HRP STABILZYME, HRP STABILGUARD, and HRP F1H (In-house). Stability test on standard calibrators of mitragynine was performed without adding any stabilizers. The reagents to be tested were kept at 4°C and 37°C respectively for a period of 10 weeks. The ELISA assay was performed on day 0, 1, 3, 5, 7, 14, 21, 28, 35, 42, 49, 56, 63, and 70 by using the reagents that were kept at 4°C and 37°C respectively. The results obtained were recorded and the respective graphs were plotted. Results & DiscussionFor stability tests on antibodies against mitragynine and horseradish peroxidase labeled with mitragynine, the results showed that both were stable either by using HRP STABILZYME, HRP SELECT, HRP STABILGUARD or HRP F1H (In-house) at 4°C and 37°C compared with control, for up to 10 weeks. Using an accepted extrapolation formula, stability for 10 weeks at 37°C translates to 25 months at 4°C. Stability on standard calibrators showed that degradation occurred after one week being stored at 4°C in buffer solution. The readings decreased tremendously when kept in buffer solution at 37°C on day 1 compared with day 0. ConclusionHRP STABILZYME, HRP SELECT, HRP STABILGUARD and HRP F1H (In-house) can be used as stabilizers for antibodies against mitragynine and horseradish peroxidase labeled with mitragynine. In addition, the standard calibrators of mitragynine were only stable at 4°C for one week in buffer solution.