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Forensic Chemical Analysis

NCJ Number
Law Enforcement Technology Volume: 31 Issue: 4 Dated: April 2004 Pages: 80,82,84,85
Doug Hanson
Date Published
April 2004
4 pages
This article describes the forensic methods used in organic and inorganic chemical analysis of crime-scene evidence.
Much evidence requires detailed chemical analysis to determine what it is and how it fits into what has occurred and who was present at a crime scene. Modern chemical analysis is often required when crimes involve illegal drugs, explosive and bomb residues, paints, solvents, fire accelerants, glass and plastic, fabrics, dyes, and various other materials at a crime scene. Organic compounds contain one or more carbon atoms. Organic chemicals include the majority of compounds found at a crime scene, since all living material is composed of organic compounds; hair, tissue, blood, and DNA are all composed of various organic chemicals; and fibers, clothing, plastics, and plant materials are all composed of a characteristic, identifiable set of organic chemicals. Organic analysis is usually performed by a combination of two methods: chromatography (separation) and spectrophotometry (identification and quantification). This article briefly describes the purposes and procedures of the following types of organic chemical analysis: chromatography, spectrophotometry, gas chromatography, gas chromatography/mass spectrometry, high-performance liquid chromatography, LC-mass spectrometry, and infrared spectrophotometry. Inorganic chemical analysis pertains to elemental chemicals and those that do not contain carbon atoms. Atomic absorption spectroscopy and inductively coupled plasma-atomic emission spectroscopy can be used for this type of chemical analysis. A special area of chemical analysis that has developed since the September 11, 2001, events is the analysis for potential chemical warfare agents. These agents, mostly neuro-toxins, are a combination of organic and inorganic compounds and can be analyzed by the instrumentation in a forensic chemistry laboratory.