Toxicological Analysis: Drug Screening and Confirmation

This chapter provides a snapshot of the most common methods and approaches to drug screening and confirmation and includes some of the more recent developments in analytical methodology. Screening tests provide an indication of the absence or presence of a drug or drug class in an exhibit, but do not necessarily provide unequivocal proof of the presence of a drug or drug class. The first step in any analysis is the isolation of drugs and poisons from the sample. In modern forensic laboratories, one or more forms of mass spectrometry are used to confirm the presence of chemical substances. Immunoassay screening techniques rely on the competition of the analyte and the labelled antigen with an antibody showing selectivity and reasonable sensitivity for a class of related drugs or sometimes just a single substance. It is essential that any methods used in the laboratory are properly assessed for their suitability and appropriateness for the application.