Comparison of methadone level measurement by enzyme immunoassay with Gas chromatography–mass spectrometry

Introduction: Determination of poisoning and its type in drug poisoning is one of the important challenges of the forensic laboratory, given that drugs have therapeutic, toxic and pathogenic doses. In this study, we tried to measure the blood level of methadone with enzyme immunoassay and compare it with Gas chromatography–mass spectrometry methodMethods: Samples were developed in the methadone treatment center for addiction treatment. The ELISA kit was purchased from RANDOX Company and performed according to the protocol set forth on the respective test kit, and then the results were obtained. Methadone s analytical standard was provided by Sigma-Aldrich. Serum samples were extracted by alkaline extraction with ethyl acetate.Results: The results were analyzed statistically. The result of the relative error in the accuracy of one day ELISA method was 3. 3% and the GC / MS method was 4/4% and the result of the relative error in the accuracy in the ELISA method was 4.1% and in the GC/MS method was 2.3%. The GC/MS method was linear from 30 ng to 10 μg, but the ELISA method was linear from 1.2 to 100 ng. And both methods did not interfere with the materials contained in the matrix and with drugs similar to methadone.Conclusion: The proposed GC/MS method is preferable to RANDOX s ELISA kit, given its high ability in methadone analysis at different concentrations. But given the time consuming, the great effort, and the high cost, the hazards of chemical solvents and the complexity of the device, it is not possible to use it everywhere and in large measure with many samples. But ELISA, with a high sensitivity and high speed, and relatively simple to use, compared to GC/MS, can analyze the number of samples in a very short time. If the methadone is positive by Gas chromatography–mass spectrometry, the ELISA method can be used to determine the blood level for a precise decision.