168
D. K. Pandey et al.
substrate has analyzed cocaine standards down to a concentration of 1 ng/mL and
the outcomes of this study indicate the possible future usefulness of the technique
for onsite testing [187].
4.3.4 Detection of Explosive Materials
Explosives represent a field of forensic chemistry in which the material may present
a deadly danger to the public at large [188]. Research of explosives is conducted by
both national security departments engaged in pre-explosion identification and law
enforcement agencies dealing with post-blast investigations [189]. Among various
explosives, trinitrotoluene (TNT) is an extremely dangerous and explosive nitroaromatic compound and a source of concern internationally. TNT is most widely used
as an explosive substance for guided explosions [190] but is being employed for
several years in military and terrorist activities such as improvised explosive devices
(IEDs) and landmines production [191]. Wu et al. recently presented a review
concentrating primarily on techniques for enhancing the Raman spectroscopic technique including alteration of the SERS substrate and surface efficiency of explosive detection [192]. Elbasuney and group employed laser-induced Raman spectroscopy to detect spectra from the three main explosive categories: nitric esters,
nitro-compounds, and nitramines. The result was that explosives could be separated from all three explosive groups except for nitrocellulose [193]. Elbasuney and
colleagues used Raman spectroscopy for the identification of IEDs-related explosive
substances and obtained more detailed profiles for the compounds used (ammonium
nitrate, urea nitrate, fuel oil, ammonium perchlorate, and nitroguanidine) [194]. Most
recently, Diaz, and Hahn used Raman spectroscopy as a sensor for the detection
of ammonium nitrate (as an explosive precursor often used in IEDs) [195]. Using
the utility of Raman spectroscopy, authors have achieved a relative limit of detection (LOD) of ammonium nitrate in water 0.1% (1 mg/g), and the absolute limit of
detection was 1.0 μg. The interest in using SERS for explosive detection has also
reappeared, as illustrated by a review article by Wu et al. that deals only with SERS
for explosive analysis [192]. In this regard, the Faulds group used SERS to detect
TNT, hexanitrostillbene (HNS), and 2,4,6-trinitrophenyl methylnitramine (tetryl),
with an outstanding LOD of 135.1 ng mL
−1 for HNS, 17.2 ng mL
−1 for tetryl, and
6.81 ng mL
−1 for TNT as a fast, sensitive and selective technique [196]. These recent
studies show potential for the production of Raman spectroscopy based rapid and
portable assays that can be used in the field to achieve accurate and quantitative
identification.
4.4 Food Analysis
With the globalization of food and its complex networking mechanism, a wide variety
of food pollutants is introduced into the food system that can occur inadvertently,
D. K. Pandey et al.
substrate has analyzed cocaine standards down to a concentration of 1 ng/mL and
the outcomes of this study indicate the possible future usefulness of the technique
for onsite testing [187].
4.3.4 Detection of Explosive Materials
Explosives represent a field of forensic chemistry in which the material may present
a deadly danger to the public at large [188]. Research of explosives is conducted by
both national security departments engaged in pre-explosion identification and law
enforcement agencies dealing with post-blast investigations [189]. Among various
explosives, trinitrotoluene (TNT) is an extremely dangerous and explosive nitroaromatic compound and a source of concern internationally. TNT is most widely used
as an explosive substance for guided explosions [190] but is being employed for
several years in military and terrorist activities such as improvised explosive devices
(IEDs) and landmines production [191]. Wu et al. recently presented a review
concentrating primarily on techniques for enhancing the Raman spectroscopic technique including alteration of the SERS substrate and surface efficiency of explosive detection [192]. Elbasuney and group employed laser-induced Raman spectroscopy to detect spectra from the three main explosive categories: nitric esters,
nitro-compounds, and nitramines. The result was that explosives could be separated from all three explosive groups except for nitrocellulose [193]. Elbasuney and
colleagues used Raman spectroscopy for the identification of IEDs-related explosive
substances and obtained more detailed profiles for the compounds used (ammonium
nitrate, urea nitrate, fuel oil, ammonium perchlorate, and nitroguanidine) [194]. Most
recently, Diaz, and Hahn used Raman spectroscopy as a sensor for the detection
of ammonium nitrate (as an explosive precursor often used in IEDs) [195]. Using
the utility of Raman spectroscopy, authors have achieved a relative limit of detection (LOD) of ammonium nitrate in water 0.1% (1 mg/g), and the absolute limit of
detection was 1.0 μg. The interest in using SERS for explosive detection has also
reappeared, as illustrated by a review article by Wu et al. that deals only with SERS
for explosive analysis [192]. In this regard, the Faulds group used SERS to detect
TNT, hexanitrostillbene (HNS), and 2,4,6-trinitrophenyl methylnitramine (tetryl),
with an outstanding LOD of 135.1 ng mL
−1 for HNS, 17.2 ng mL
−1 for tetryl, and
6.81 ng mL
−1 for TNT as a fast, sensitive and selective technique [196]. These recent
studies show potential for the production of Raman spectroscopy based rapid and
portable assays that can be used in the field to achieve accurate and quantitative
identification.
4.4 Food Analysis
With the globalization of food and its complex networking mechanism, a wide variety
of food pollutants is introduced into the food system that can occur inadvertently,