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Acing the Tests

Advanced tools for detecting drugs and blood alcohol content provide excellent evidence.

May 28, 2010  |  by Tim Dees - Also by this author

No-touch Analysis

A relatively new application of an old technology allows officers to identify suspect drugs without sampling or touching the drug, and sometimes without even opening its packaging.

Raman spectroscopy (named after one of the people who first described it in 1928) measures the shift in energy of photons emitted when laser light strikes the substance in question. This energy profile is unique for each molecule, so any chemical substance is identifiable by comparing the profile against a standard. There's no need to sample or touch the substance in question. The analysis can be done through a plastic bag or other clear container.

Full-scale Raman spectroscopy requires quite a bit of equipment, but the bulk is reduced considerably when you limit the substances you can identify. A device called the ReporteR packs the technology into a handheld device a bit larger than a pack of cigarettes. The device, manufactured by DeltaNu, contains the laser, a collector for the emitted photons, and a database of profiles of commonly encountered drugs of abuse.

When a user points the laser at a suspect drug, the device analyzes the profile of the substance and compares it to the information stored in the ReporteR. A display shows a match with one of the stored profiles or a "no match" indication. There is enough memory to hold the profiles of nearly all commonly encountered drugs of abuse, so this is a single-test solution with no consumables. The device comes with a liquid vial attachment for analysis of solutions. The operator can save each test result and print out a report later, if desired.

Alcohol Testing in the Field

Although the number of alcohol-related fatalities has steadily declined, driving under the influence of alcohol remains a major factor in injury and non-injury accidents, and an enforcement priority for most police agencies.

Field sobriety testing is more standardized and definitive than ever before. Still, there is an experiential factor for officers administering these tests, and defense attorneys will use any actual or perceived error to try to discredit the officer and his or her decision to arrest. Fortunately, there is technology to aid officers in taking drunk drivers off the road.

Breath testing is the most common method for measuring blood-alcohol concentration (BAC). While not as accurate as a blood test, it is less invasive, faster, and less expensive than drawing blood and having it analyzed in a laboratory. Breath testing technology has been slowly evolving for more than 70 years, and nearly every method is still used today in some form.

The "drunkometer" was first used in 1938. The subject blew into a tube that inflated a balloon inside the test device. The breath sample was pumped through an acidified solution of potassium permanganate, which changed color if alcohol was present. The greater the color change, the more alcohol was present.

Today, companies such as Dräger (which also produces sophisticated evidentiary breath testers and other medical equipment) still sells Alcotest Tubes, which use a similar chemical reaction color change to show the presence of alcohol in a breath sample.

CONTINUED: Acing the Tests «   Page 2 of 3   »

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