These method do, however, pose the greatest technical challenges due to the relatively large distances involved and the requirement for high sensitivity. There are several spectroscopic techniques that can be used when looking at IEDs and only a very brief overview will be given in this article. Most of the methods are laser-based, that is, a laser is used to interact with, or excite, the target compounds with the resultant changes in radiation measured through spectroscopic means. Laser induced spectroscopic methods can either be applied to species in the gaseous phase, such as laser absorption spectroscopic detection of TATP15
or in
the solid state using techniques such as Raman spectroscopy16
breakdown spectroscopy (LIBS)17,18
and laser induced .
Non-laser based spectroscopic techniques such as millimetre wave (MMW) imaging and terahertz spectroscopy also show promise in the field of IED detection15,17
. These have
some profound advantages over other standoff methods since radiation in the MMW region of the electromagnetic spectrum can penetrate clothes while the moderate intensities needed are safe for human application.
The
problem with MMW imaging, however, is that there is no distinctly identifying features in the spectra at these wavelengths and it takes radiation in the terahertz range to reveal any spectral detail. Spectroscopy in the terahertz region is, however, relatively unexplored and much work is needed on modelling and interpretation of spectra such that species related to IEDs can potentially be detected.
References 1. 2. 3. 4. 5. 6. 7. 8. 9.
Conclusions Both pre- and post-blast detection of IEDs is becoming increasingly important as the number and nature of premeditated attacks increase. Speed and accuracy are the key requirements in the detection and identification of explosives especially in high risk, high throughput areas such as airports. The trade-off between analysis speed and accuracy is ongoing but recent innovations such as the coupling of multiple robust liquid chromatographic techniques in series and the development of new sampling interfaces has demonstrated the possibility to reduce analysis time significantly. Portable instrumentation also offers the potential for reduced analysis time since analyses can be performed and results reported on site.
Furthermore, such
portable instrumentation can increase accuracy by minimising sample handling and the potential for contamination. Standoff detection of IEDs, or those who have prepared them, offers significant advantages over direct detection methods. Spectroscopic methods are ideally suited to standoff detection and this will be a major area of growth in the coming years.
Finally it should also be noted that it will take more than one “perfect” technique to cover the detection and identification requirements for all IEDs. The long term solution will involve a suite of methods, each one tailored for the particular application. In this manner not only can the speed of analysis be minimised through careful optimisation of the method, but confirmatory analyses will also be available as validation, thereby improving the accuracy and trustworthiness of results.
R.M. Burks, D.S. Hage, Analytical and Bioanalytical Analysis 395 (2009) 301.
Y. Takada, H. Nagano, Y. Suzuki, M. Sugiyama, E. Nakajima, Y. Hashimoto, M. Sakairi, Rapid Communications in Mass Spectrometry 25 (2011) 2448. E. Tyrrell, G.W. Dicinoski, E.F. Hilder, R.A. Shellie, M.C. Breadmore, C.A. Pohl, P.R. Haddad, Journal of Chromatography A 1218 (2011) 3007. E. Tyrrell, E.F. Hilder, R.A. Shalliker, G.W. Dicinoski, R.A. Shellie, M.C. Breadmore, C.A. Pohl, P.R. Haddad, Journal of Chromatography A 1208 (2008) 95. C. Sarazin, N. Delaunay, A. Varenne, J. Vial, C. Costanza, V. Eudes, J.-J. Minet, P. Gareil, Journal of Chromatography A 1217 (2010) 6971. C. Sarazin, N. Delaunay, C. Costanza, V. Eudes, P. Gareil, Electrophoresis 32 (2011) 1282.
J.P. Hutchinson, C.J. Evenhuis, C. Johns, A.A. Kazarian, M.C. Breadmore, M. Macka, E.F. Hilder, R.M. Guijt, G.W. Dicinoski, P.R. Haddad, Analytical Chemistry 79 (2007) 7005. J.P. Hutchinson, C. Johns, M.C. Breadmore, E.F. Hilder, R.M. Guijt, C. Lennard, G.W. Dicinoski, P.R. Haddad, Electrophoresis 29 (2008) 4593. G.A. Blanco, Y.H. Nai, E.F. Hilder, R.A. Shellie, G.W. Dicinoski, P.R. Haddad, M.C. Breadmore, Analytical Chemistry 83 (2011) 9068.
10. P.M. Flanigan, J.J. Brady, E.J. Judge, R.J. Levis, Analytical Chemistry 83 (2011) 7115. 11. M.E. Sigman, C.D. Clark, R. Fidler, C.L. Geiger, C.A. Clausen, Rapid Communications in Mass Spectrometry 20 (2006) 2851. 12. R.-M. Rasanen, M. Nousiainen, K. Perakorpi, M. Sillanpaa, L. Polari, O. Anttalainen, Utriainen, Analytica Chimica Acta 623 (2008) 59. 13. S. Yamaguchi, T. Uchimura, T. Imasaka, T. Imasaka, Rapid Communications in Mass Spectrometry 23 (2009) 3101. 14. M. Makinen, M. Nousiainen, M. Sillanpaa, Mass Spectrometry Reviews 30 (2011) 940. 15. U. Willer, W. Schade, Analytical and Bioanalytical Analysis 395 (2009) 275. 16. B. Zachhuber, G. Ramer, A. Hobro, E.t.H. Chrysostom, B. Lendl, Analytical and Bioanalytical Chemistry 400 (2011) 2439. 17. S. Wallin, A. Pettersson, H. Ostmark, A. Hobro, Analytical and Bioanalytical Analysis 395 (2009) 259. 18.
J.L. Gottfried, F.C. De Lucia Jr, C.A. Munson, A.W. Miziolek, Analytical and Bioanalytical Analysis 395 (2009) 283. 20 Download your FREE ASI "iPad/iPhone APP" NOW February 2012 Aviationsecurityinternational
Philip Zakaria, Greg W. Dicinoski and Michael C. Breadmore are at the Australian Centre for Research on Separation Science, School of Chemistry, University of Tasmania, Private Bag 75, Hobart, Tasmania 7001, Australia.
Zakaria
Dicinoski
Breadmore
The Australian Centre for Research on Separation Science (ACROSS) is a multi-institutional research
centre
focused on the development and application of leading edge analytical separations based on chromatography and electrophoresis. It has been funded for the past 7 years to develop analytical technology for the detection of inorganic explosives, both pre- and post-blast. A number of methods have been developed and adopted by laboratories associated with law enforcement, while prototype technology for portable field analyses is currently being developed.
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