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KEY POINTS

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  • Analytic toxicology involves the application of the tools of analytic chemistry to the qualitative and/or quantitative estimation of chemicals that may exert adverse effects on living organisms.

  • Forensic toxicology involves the use of toxicology for the purposes of the law; by far the most common application is to identify any chemical that may serve as a causative agent in inflicting death or injury on humans or in causing damage to property.

  • The toxicologic investigation of a poison death involves (1) obtaining the case history in as much detail as possible and gathering suitable specimens, (2) conducting suitable toxicologic analyses based on the available specimens, and (3) the interpretation of the analytic findings.

  • The toxicologist as an expert witness may provide two objectives: testimony and opinion. Objective testimony usually involves a description of analytic methods and findings. When a toxicologist testifies as to the interpretation of analytic results, that toxicologist is offering an “opinion.”

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INTRODUCTION

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With its roots in forensic applications, 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. Forensic toxicology involves the use of toxicology for the purposes of the law. The most common application is to identify any chemical that may serve as a causative agent in inflicting death or injury on humans, or in causing damage to property. 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 a reasonable degree of scientific probability or certainty. For this reason, forensic toxicology and analytical toxicology have long shared a mutually supportive partnership.

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ANALYTICAL TOXICOLOGY

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Forensic toxicologists learned long ago that when the nature of a suspected poison is unknown, a systematic, standardized approach must be used to identify the presence of most common toxic substances. An approach that was first suggested by Chapuis in 1873 in Elements de Toxicologie is based on the origin or nature of the toxic agent. Such a system can be characterized as follows:

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  1. Gases—Gases are most simply measured by means of gas chromatography.

  2. Volatile substances—These are generally liquids of various chemical types that vaporize at ambient temperatures. Gas chromatography is the simplest approach for separation and quantitation.

  3. Corrosive agents—These include mineral acids and bases. Many corrosives consist of ions that are normal tissue constituents. Chemical techniques can be applied to detect these ions when they are in great excess over normal concentrations.

  4. Metals—Metals are encountered frequently as occupational and environmental hazards. Separation involves destruction of the organic matrix by chemical or thermal oxidation.

  5. Anions and nonmetals—These present an analytical challenge as they are rarely encountered in an uncombined form.

  6. Nonvolatile organic substances—These constitute the largest group of substances that must be considered by analytical toxicologists. This group ...

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