Analysis, Stability and Distribution of Pharmaceuticals and Drugs of Abuse over a Period of One Year in Formalin-Fixed Liver and Formalin Solutions.

This article focuses on the development and application of a validated ultra high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS-MS) method for analyzing the stability of 84 drugs of abuse and pharmaceuticals in formalin-fixed human liver tissues and corresponding formalin solutions over a 12-month period. The study, involving 14 forensic cases with known drug use, found that drug detectability significantly decreases over time in fixed tissues, with only 17% of initially detected substances remaining after one year, while some drugs showed migration into the formalin solution. Specific findings include the persistence of methadone and certain benzodiazepines (e.g., diazepam, 7-aminoflunitrazepam) in both tissues and formalin for up to 12 months, whereas morphine was undetectable post-fixation. These results provide important forensic toxicology insights for interpreting toxicological analyses when only formalin-fixed tissues or solutions are available, although they do not allow for quantitative conclusions regarding cause of death.