Chapter 27 - Liquid chromatography in forensic toxicology

Abstract

Forensic toxicology is a branch of forensic science that consists of the systematic collection and interpretation of evidence to solve crimes. In particular, forensic toxicology is a multidisciplinary science combining the principles of toxicology, analytical chemistry, clinical chemistry, pharmacology, and anatomic pathology to investigate the cause of fatal and non-fatal intoxications constituting a crime. Since the first analytical method was developed in 1832, analytical toxicology has drastically evolved in response to the new challenges. The development of separative analytical techniques such as chromatography has represented an important step forward in forensic analysis, thanks to their versatility. Ante-mortem toxicological analyses concern the analytical determination of drugs and poisons in biological matrices obtained from living subjects actively, passively, intentionally, and/or unintentionally exposed to those compounds. Post-mortem analysis is required to prove that a drug or a poison contributed to or was the cause of death. However, changes occur after death, which should be considered during toxicological analysis. Sample pretreatment plays a crucial role in analytical chemistry, especially when complex matrices such as biological specimens are investigated. The most widely used techniques have been liquid/liquid extraction (LLE) and solid phase extraction (SPE). A novel approach for sample pretreatment in forensic toxicology is the so-called QuEChERS, which stands for Quick, Easy, Cheap, Effective, Rugged, and Safe and consists of solvents, reagents, and salts to precipitate matrix components and interferences. Concerning the most relevant class of target analytes of forensic analysis are prescription drugs, drug of abuse, new psychoactive substances, alcohol biomarkers. A particular attention should be paid to the central nervous system depressant Gamma-hydroxybutyrate (GHB), benzodiazepines and Z-drugs. UHPLC- or HPLC–MS/MS has proved to be the most suitable techniques for this purpose. Recent improvements in mass spectrometry have led to higher detection capabilities and faster analysis, thanks to the advantages of new technologies such as high-resolution mass spectrometry (HRMS), achieving accurate mass measurements.