What Is Chemical Detection?

Maggie J. Hall

Chemical detection systems are generally used to sense and identify chemical agents in air, soil, or water. Law enforcement officers, industrial work sites, and the military may use different types of detection systems to alert personnel to the existence of harmful or toxic substances. Scanners, sensors, and spectrometers are common types of chemical detection system equipment.

Chemical detection might be done by law enforcement officers at a crime scene.
Chemical detection might be done by law enforcement officers at a crime scene.

In crime scene investigations, law enforcement officers might use hand held devices that take air samples and analyze them for the existence of particular substances. The tracers may detect air particles containing explosives, like nitroglycerin, or narcotic substances, such as marijuana and methamphetamines. A handheld or desktop chemical detection system might also analyze physical samples for the presence of certain chemicals. These devices incorporate the use of swabs that capture particles when rubbed over surfaces. By inserting the swab into the device, the machine analyzes and identifies possible substances located on the object.

Chemical detection devices may be used to screen for drugs such as marijuana.
Chemical detection devices may be used to screen for drugs such as marijuana.

For the purpose of public safety, airports and other public areas may employ the use of portal detectors that monitor for possible explosives or narcotic chemicals. The noninvasive, automated devices analyze the air around individuals standing in the portal. The machine immediately detects and identifies any illegal substances emitted into the air by individuals or their clothing.

Industrial work sites may use stationary detectors in specific areas, hand held devices, or chemical detection systems worn by employees. Stationary devices generally sound an alarm when air quality is jeopardized by elevated levels of toxic substances. Employees can use hand held devices that scan work areas or the clothing of personnel entering or exiting a specific location. An armband chemical detection system may contain a number of small cassettes that monitor and change color in the presence of toxic gases.

The military commonly use chemical warfare agent detectors. Chemical detection systems can alert personnel to the presence of gaseous, liquid, or solid chemicals that include blistering agents, nerve gas, and other substances designed to kill or cause serious injury. These devices may be handheld or portable table top models.

Scanners and sensors may detect substances by the amount of fluorescence observed under a particular wavelength of light. Using a laser beam, a sensor might also measure particle mass by measuring the amount of light deflection that occurs as the beam passes through the particles. Samples placed in a spectrometer are split into molecules by an electron beam. The particle fragments then pass through a vacuum and a magnetic field where the molecules are identified by their mass to charge ratios.

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