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Sherlock Holmes Forensic Series: Toxicology

As a forensic toxicologist, it is my job to either rule out or confirm the presence of a particular substance as a potential cause of death. I test for a number of things including alcohol, illegal or prescription drugs, toxic chemicals, metals and gases such as carbon monoxide or cyanide. Any substance can be toxic if administered in sufficient quantities. Poisons are considered to be those substances which produce harmful effects in small quantities.

The investigation starts by examining the crime scene for evidence such as pill bottles, powders, trace residue, toxic plants or chemicals. Great care must be taken when collecting specimens to prevent cross contamination, and every step of the process must be documented. It is the job of the forensic toxicologist to perform a series of analytical tests in order to determine which substances are present in  biological specimens and in what concentrations.

There are a number of techniques used for initial screening of specimens. Certain analytical procedures such as the Marsh test for arsenic did exist in the times of Sherlock Holmes. Today, analytical methods are far more specific and sensitive. Initial screening can also be performed by Immunoassay, a biological test using antibodies. This is followed by using various methodologies to confirm the presence of one or more substances and to determine the quantities in various specimens. The most commonly used methods include Gas Liquid Chromatography, high performance Liquid Chromatography, and Mass Spectrometry.

Sherlock Holmes Exhibit

The International Exhibition of Sherlock Holmes was developed by Exhibits Development Group and Geoffrey M. Curley + Associates in collaboration with the Conan Doyle Estate Limited, the Oregon Museum of Science and Industry, and the Museum of London.

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