Chapter 32: Analytical and Forensic Toxicology

INTRODUCTION

It is impossible to consider the topic of forensic toxicology without discussing analytical toxicology in detail, as analytical toxicology has its roots in forensic applications. Therefore, it is logical to discuss these mutually dependent areas together. Analytical toxicology involves the application of the tools of analytical chemistry to the qualitative and/or quantitative estimation of chemicals that may exert effects on living organisms. Generally, the chemical that is to be measured (the analyte) is a xenobiotic that may have been altered or transformed by metabolic actions of the organism. Frequently, the specimen that is to be analyzed consists of a matrix composed of body fluids or solid tissues removed from the organism. Both the identity of the analyte and the complexity of the matrix can present formidable problems to an analytical toxicologist.

Forensic toxicology involves the use of toxicology for the purposes of the law (Cravey and Baselt, 1981). Although this broad definition includes a wide range of applications, such as regulatory toxicology and workplace urine testing to detect drug use, by far the most common application is to identify any chemical that may serve as a causative agent in inflicting injury or death on humans, or in causing damage to property. Frequently, as a result of such unfortunate incidents, charges of liability or criminal intent are brought that must be resolved by the judicial system. At times, indirect or circumstantial evidence is presented in an attempt to prove cause and effect. However, there is no substitute for the unequivocal identification of a specific chemical substance that is demonstrated to be present in tissues from the victim at a sufficient concentration to explain the injury with certainty. For this reason, forensic toxicology and analytical toxicology have long shared a mutually supportive partnership.

To aid in deciding whether adverse effects of xenobiotics contribute to death, injury, or other harm to persons or property, great efforts are made to initiate and implement analytical procedures in a forensically credible manner. Laws prescribing punishment to drug-impaired drivers are evidence of attempts to mitigate impaired driving. The measurement of ethanol in blood or breath at specific concentrations is generally required to prove impairment by this agent (Fisher et al., 1968). Similarly, the decade of the 1980s saw a growing response by society to the threat of drug abuse. Identification of drug users through testing urine for the presence of drugs or their metabolites, using methods and safeguards developed by forensic toxicologists, has become required by law (Department of Health and Human Services, 1988).

The diagnosis and treatment of health problems induced by chemical substances and the closely allied field of therapeutic drug monitoring also rely greatly on analytical toxicology. Although the analytes are present in ...