A Practical Approach to Determine Cutoff Concentrations for Opiate Testing with Simultaneous Detection of Codeine, Morphine, and 6-Acetylmorphine in Urine

Background: Both the Department of Defense (DoD) and the Department of Health and Human Services (DHHS) currently require two confirmation tests to verify use of heroin, one test for total morphine and a separate test for 6-acetylmorphine (6-AM). Our aim was to determine appropriate free-codeine, free-morphine, and 6-AM cutoff concentrations that could be substituted for total-morphine, total-codeine, and 6-AM cutoff concentrations and to develop a less labor-intensive method for measuring codeine, morphine, and 6-AM. Methods: Urine samples containing opiates were extracted, derivatized, and analyzed using gas chromatography–mass spectrometry with selective ion monitoring. Results: The limits of detection for codeine, morphine, and 6-AM were 6, 5, and 0.5 μg/L, respectively. Recoveries were >90%. Quantification was linear over the concentration range of 6–1000 μg/L for codeine, 5–5000 μg/L for morphine, and 0.5–800 μg/L for 6-AM. Cutoff concentrations for confirmation of opiates were 100, 100, and 10 μg/L for free codeine, free morphine, and 6-AM. Conclusion: The proposed cutoff concentrations for free morphine and 6-AM provide better detection windows for morphine and heroin use than the cutoff concentrations for total morphine and 6-AM used at present. Detection of free codeine, instead of total codeine, simplifies interpretation of codeine use. The single-extraction method enables simultaneous, less labor-intensive analysis of morphine, codeine, and 6-AM.