DETECTION
on the subject Shedding light
Nick Vent and John Johnson explain how fi rst responders use lab-proven technology to mitigate and minimize chemical emergencies
W
hen a chemical emergency occurs, the main priorities of fi rst responders are to ensure the safety of
the public and to minimize any future damage. To do this eff ectively, it is essential that responders be properly equipped with both the right tools and accurate information, as the appropriate response can vary greatly depending on the specifi c chemicals involved. Emergency situations involving dangerous or lethal chemicals occur frequently, from shipping industry accidents to illicit drug manufacturing, and improvised explosive devices (IEDs) are a concern worldwide. Additionally, the possibility of a chemical terrorist attack using common industrial chemicals as weapons of convenience and opportunity is a recognized vulnerability. Well-trained and equipped emergency personnel are essential to averting or minimizing
FirstDefender RMX being used in an explosives training course.
the damage of these potential disasters.
Advances in spectroscopy One of the most eff ective tools for rapid and accurate analysis of unknown materials is vibrational spectroscopy. Just like with visible light, every chemical substance has its own unique ways that it absorbs, refl ects, scatters and emits light. Spectroscopy is the process of measuring the amount of light at diff erent wavelengths coming off a material. By comparing the highly detailed digital data that is captured to a database of previous results, unknown materials can be identifi ed in seconds, allowing fi rst responders to identify threats and plan further actions. Thermo Fisher Scientifi c has developed
two product families for use by military and civilian fi rst responders for chemical identifi cation: both are rugged, handheld instruments for use downrange in hazard zones. The Thermo Scientifi c TruDefend-
er instruments use mid-IR Fourier Transform (FTIR) spectroscopy, a technique that bombards a substance with a broad spectrum of light and measures the amount of light absorbed at each wavelength in the spectrum. The Thermo Scientifi c FirstDefender
instruments use Raman spectroscopy. Here, a single wavelength laser strikes the substance, the sample scatters some of the light into diff erent wavelengths, and the device measures this light at diff erent wavelengths. Each device has diff erent situations for which it excels, and together they provide complemen- tary and confi rmatory results to the user. The large displays are easy to view
through protective gear, and at less than 1.4 kg each, they are ideal standard kit for military personnel and fi rst respond- ers in almost any chemical or explosives incident. In the rare case that an unknown substance isn’t identifi ed by the devices’ internal library, chemists are available 24/7 by phone to assist with spectral analysis.
Understanding limitations In order to use these devices to their greatest advantage, it is vital that fi rst responders understand their strengths and limitations. Raman spectroscopy, which powers the FirstDefender™ analyser, is most notable because it is non-contact. It uses a laser which can penetrate translucent containers to identify unknown chemicals, making Raman ideal for contained materials that the responder may not want to disturb.
Thermo Scientifi c TruDefender FT
spectrometer (FTIR).
Thermo Scientifi c FirstDefender RMX spectrometer (Raman).
58 CBNW 2013/01
Images: ©Thermo Fisher
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