Determination of indirect heroin biomarkers in biological samples of heroin users

Heroin use is responsible for many drug-related deaths, so the determination of its biomarkers, except for 6-acetylmorphine, in biological samples, is of particular concern in toxicological laboratories worldwide, for a better investigation of these cases. Th use of 6-acetylmorphine as a heroin biomarker has some limitations due to its rapid bioconversion to morphine within a few hours, especially in blood samples. The need for new indirect biomarkers, like the ones that come from the processing of opium during the clandestine production of heroin, becomes imperative. A GC/MS method was developed and validated for the determination of meconin, thebaine, papaverine, acetylcodeine and noscapine, along with morphine, codeine and 6-acetylmorphine, in different biological samples of heroin users. For all analytes and all individual biological samples, the LOD and LOQ were 2.00 and 5.00 ng/mL, respectively, the calibration curves were linear (R²≥0.991) from 5.00 to 500.0 ng/mL, and absolute recoveries were higher than 91.9 %. The method was applied during the toxicological investigation of 34 forensic cases after positive immunoassay screening for opiates. The results indicate that meconin is the most frequently detected indirect biomarker of heroin use, as it was found in 91.2 % of all cases, whilst in 23.5 % of them no 6-acetylmorphine was detected. Papaverine was found in 67.6 % of all cases and is considered to be the second most important indirect biomarker of heroin use. The establishment of detecting meconin and papaverine in biological materials in parallel with the detection of morphine, codeine and 6-acetylmorphine can contribute to more conclusive results concerning heroin use in forensic cases.