are these liquids explosive?
-a team of researchers from the University of the Basque country (UPV/EHU) has developed a method for determining the chemical composition of suspicious liquids for explosives seized police. Some of the samples contain substances hazardous to health, such as methanol and boric acid
Spain, 2011-August every year security forces confiscated tons of pyrotechnic substances in principle, for the manufacture of fireworks of low power (such as flares or those used in artistic or sports events), but that may also end up in the hands of hooligans or violent groups.
Now a group of chemists at the University of the Basque country (UPV/EHU) has developed a method which provides the judges conclusive scientific evidence about the nature of such liquids. Until now many ways to the detection of high explosives, such as TNT, had engaged but only for minor power, although they can also be dangerous.
“ Have combined four techniques commonly used in laboratories to determine relatively easily, explosive or flammable compounds in liquids of dubious origin â€, emphasizes SINC Kepa Castro, researcher at the UPV/EHU and lead author of the study
On the one hand, the molecular composition of substances is obtained with two spectroscopic techniques (Raman and infrared), which can be carried out with portable devices in airports, customs and port offices.
EDS false color of one of the analyzed liquid waste. The red color corresponds to the energies of bromine, the sulfur blue and green to the phosphorus. Image: K. Castro et al. / UPV-EHU.
On the other hand, to determine what elements present the sample uses a detector energy dispersive (EDS), to adding images that provides an electronic scanning microscope (SEM).
“ With the technique SEM-EDS visualizes how are distributed and grouped the elements in the sample (calcium with sulfur suggests the presence of a calcium sulfate, for example) â€, explains Castro, “ and across the four techniques data can corroborate or confirm the results â€.
Samples with hazardous compounds
To validate the method scientists have applied it on five samples of confiscated liquids. Four of them, the results are consistent with its use for fireworks of low power. Alcohols such as the isopropyl and methanol were used for solubility compounds and the scientists managed to produce flames of colors.
The use of methanol as a main solvent was a surprise for the team, this compound is very toxic to humans (cause acidosis and blindness) and its use is restricted in many countries.
Boric acid, a substance recently joined the list was also detected in other fluids of the “ highly troubling †of the REACH Regulation (registration, evaluation, authorisation and restriction of chemicals) of the European Union. These acids can affect negatively human reproductive function.
The fifth sample not surprisingly found no substance that entered the ignition or develop. “ Probably a delay you flame, which is used just to otherwise: prevent fire â€, suggests the researcher.
Bibliographic reference:
KEPA Castro, Silvia Vallejuelo Fdez-Ortiz, Izaskun Astondoa, Felix M. Goñi, Juan Manuel Madariaga. “ Are these liquids explosive? Forensic analysis of indoor fireworks confiscated â€. Analytical and Bioanalytical Chemistry 400: 3065 – 3071, 2011. DOI 10.1007/s00216-011-5013-4
