Optimizing Analytical Parameters for Detection of Chronic and Single Dose Drug Exposure in Forensic Hair Analysis

In forensic toxicology, retrospective biomonitoring of drug use is most commonly done by analysis of hair. Advantages of hair include the ability to perform segmental analysis to determine timelines of use and/or abstinence. This is of particular significance in drug-facilitated crime (DFC), when blood and urine samples may not be available due to delayed reporting of the event. However, hair analysis does have technical and interpretive challenges. As a solid sample matrix, it requires specialized pretreatment measures, including removal of external contamination, cutting and/or pulverization, and extraction to recover drug systemically incorporated into the hair matrix. While general recommendations on protocols for hair analysis are available, they do not provide details on specific analytical procedures.

In previous NIJ-supported work, a Design of Experiment (DoE) approach was employed to compare the performance of various hair pretreatment and extraction parameters for selected drugs and metabolites in authentic hair reference materials (HRM) and in specimens from individual chronic drug users. This approach was successful in identifying a optimized general protocol for hair analysis for selected drugs, using liquid chromatography coupled to mass spectrometry (LC-MS/MS). The present proposal builds upon this work to further improve the performance and reliability of forensic hair testing. DoE studies will be conducted for additional drugs of abuse, with a particular focus on drugs associated with DFC. Other extraction parameters not previously tested will be assessed. The applicability of the optimized protocols for analysis of hair of different colors will be investigated. Finally, the optimized method(s) will be fully validated for adoption in forensic toxicology laboratories.

One major challenge in forensic hair analysis is the retrospective detection of single doses of drugs. DFC cases often involve ingestion of a single drug dose or of several doses within a short period of time. The resulting concentrations in hair are typically low and restricted to a narrow segment of hair, thus requiring an analytical method with high selectivity and sensitivity. To address this important issue, we will assess the performance of the optimized, validated method(s) for detection and quantitation of single drug exposures in hair.

     The outcomes of this project will have relevant applications in forensic toxicology and law enforcement. Furthermore, this work addresses current challenges in DFC cases for the detection of licit and illicit drugs in hair following single dose exposures. Results from this project are anticipated to significantly benefit forensic science for criminal justice practice. CA/NCF