SPECTROSCOPY 49
T
he use of mass spectrometry (MS), gas chromatography (GC) and the two in tandem in the detection and analysis of narcotics and explosives is well established, but the methods are becoming more refined and being applied in association with portable systems. Te latter is achieving growing popularity, in spite of drawbacks. Mobile screening systems, in the case of the on-site detection of explosives and chemical agents, can include smartphone apps, or chemical/explosive detectors worn as badges by military personnel with results cross-referenced by Cloud-based databases. Larger-scale portable devices can be used in the field and are capable of some analysis. For example, devices produced by Smiths Detection and newly devised systems such as an artificial sniffer for the security market with enhanced detection, developed by the University of Liverpool, UK, as part of
the EC project Chemsniff. However, whereas speed of detection can be vital in time- critical situations, lab-based analysis continues to be the essential means whereby in- depth analysis can be achieved for legal as well as purely scientific reasons. Dr Trisha Conti, of the
Vermont Forensic Laboratory in the USA, says, in relation to narcotics, “It seems as though many of the portable systems are used by narcotic officers as screening devices. Validation of these systems according to accreditation (ASCLD/LAB, ISO17025) and discipline- specific (SWGDRUG) standards have not been performed. Tat limits their usefulness as confirmation tools leaving conventional laboratory analysis as a requirement, since it’s defendable in court. I believe there may be labs using hand-held Raman systems after validation, but still referring to them as screening tests.”
Explosive zone D
r Natalie Mai, a research fellow at Cranfield University in the UK, uses GC-MS to analyse the gases coming
from the decompositions of explosives and the identification of the components of explosives. She explains her ongoing work in this area:
these gases allows us to investigate the ageing mechanisms of NC-based formulation.” She adds: “Unfortunately with the column but we
“We use GC-MS to understand the mechanism of degradation of ageing explosives. For example, nitrocellulose (NC) thermally degrades over time liberating gases such as NOx, a mixture of NO and NO2
. The study of we are using we cannot detect NO2
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Left: A GC/MS application for Smiths Detection technology
we are using is a single quadrupole mass spectrometer.”
definitely observe NO and N2
O. The detector
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