Trace level detection and identification of nitro‐based explosives by surface‐enhanced Raman spectroscopy

Abstract

Methods for rapid identification of explosives and their associated compounds at trace level quantities are needed for security screening applications. In this paper, we apply the surface‐enhanced Raman spectroscopy (SERS) to detect and identify traces (as low as tens of pg) of pentaerythritol tetranitrate (PETN), ethylene glycol dinitrate (EGDN), cyclotrimethylene‐trinitramine (RDX) and trinitrotoluene (TNT) using commercially available substrates (Klarite®, Renishaw diagnostics). High quality spectra were achieved within 10 s with a compact Raman spectrometer. Principal component analysis (PCA) of the data was performed to understand what factors affected the spectral variation across the samples. It was found that 76% of the spectral variation was explained by the first three PCs. Score plots for these components showed that the energetic materials can be clearly classified on the basis of SERS spectra also at trace level quantity. Our measurements further demonstrate the potential for using SERS as fast, in situ analytical tool for safety devices, with a sensitivity which competes and, in some cases, overcomes other techniques. Copyright © 2013 John Wiley & Sons, Ltd.

Recent advances in capillary electrophoresis instrumentation for the analysis of explosives

“…[45] Another advantage of Raman spectroscopy is its potential to identify compounds in a sample (fingerprinting), as Raman spectra are unique for each compound. [45,46] Nevertheless, when samples are composed of homogeneous mixtures, a separation technique is usually more useful, as this analysis allows a separation of the components prior to detection and confirmation with other techniques or validated methods.…”

“…[45] Another advantage of Raman spectroscopy is its potential to identify compounds in a sample (fingerprinting), as Raman spectra are unique for each compound. [45,46] Nevertheless, when samples are composed of homogeneous mixtures, a separation technique is usually more useful, as this analysis allows a separation of the components prior to detection and confirmation with other techniques or validated methods. [24] Besides, quantification of analytes is a difficult task when employing Raman spectroscopy; thus, this technique is not usually considered for environmental applications where quantification can be required, and is used primarily in the detection of potential compounds for security purposes or in forensic casework.…”

“…In summary, the advantages of Raman spectroscopy depend on short duration of analysis and easier sample preparation compared to the separation or other spectrometric techniques; the miniaturized format of this technique has been used for in situ analysis. [45] MS has been established as a powerful analytical technique in many analytical fields and more specifically in forensic chemistry, due to its potential to unequivocally detect the compounds present in a sample and also its quantification capability at trace levels and Fig. 4.…”

Fabrication of disposable flexible SERS substrates by nanoimprint

“…However, the negative PMMA replica were shown to present, after metallization, a high enough SERS effect and were used to detect Rhodamine 6G colorant in very low concentration (10nM). In this current work, we decided to go further by using, as a master mold, silicon microstructures that have already shown a good SERS effect [4]. By performing two-consecutive nanoimprint steps, we succeeded in elaborating, on the final flexible foil, the same morphology of SERS devices than those originally present on the master mold.…”

A facile one-step photochemical strategy for preparation of polyacrylamide functionalized CdTe(S) quantum dots and their application in sensitive determination of 2,4,6-trinitrotoluene

“…Therefore, fast and reliable detection of trace TNT has attracted considerable attentions [5]. Various analytical techniques, including gas chromatography [6,7], high performance liquid chromatography [8,9], voltammetry [10,11], ion mobility spectrometry [12,13], mass spectrometry [14,15], energy dispersive X-ray diffraction [16,17], surface enhanced Raman spectroscopy [18,19], and surface plasmon resonance [20][21][22], just name a few, have been applied in the detection of trace amounts of TNT. These techniques are all effective, but the requirement of complicated analytical instruments, lengthy and tedious operation procedures of these methods exclude their application in on-site analysis, especially in emergencies.…”