Determination of clozapine in hair and nail: The role of keratinous biological materials in the identification of a bloated cadaver case

Keratinous biological materials, such as hair and nails, offer a substantially longer retrospective window of detection compared to other body fluids. Little research on drug analysis in nails is currently being conducted. In this study, the hair and nails from a bloated cadaver was analyzed. The study showed that the forensic toxicology results of keratinous biological materials could provide valuable clues for solving cases.In this study, a method was developed for the extraction and analysis of clozapine from hair and nails. The keratinous bio-samples were washed and then pulverized using a freeze mill. After ultrasonic bath extraction, the supernatants were analyzed by ultra-performance liquid chromatography tandem mass spectrometer (UPLC–MS/MS).The method presented in this study proved to be reliable, specific, selective and sensitive with high precision and accuracy. Clozapine was found in both hair and nails from a long term user's remains, even after serious decomposition. The mean concentration of clozapine in the hair was 322.9 pg/mg and 138.3 pg/mg in the nails. Toxicological results helped police narrow the scope of the investigation and improved the efficiency of the breaking of the case.The findings of the present study demonstrated that the method can be used in forensic investigation. Toxicological results increased the efficiency of cadaver identification and the solving of the case. The study demonstrated that hair and nail analysis could provide vital clues for solving cases and showed the value of keratinous biological materials in the forensics field.