Anions in pre- and post-blast consumer fireworks by capillary electrophoresis.

Consumer fireworks are a heterogeneous group of pyrotechnic items widely used by citizens around the world. There are a wide number of forensic cases related to consumer fireworks that require knowing their chemical composition and variety of designs to conduct accurate and comprehensive analyses. In this research paper, a selection of six consumer firework types (firecracker, rocket, pyrotechnic fountain, pyrotechnic battery, sparkler, and smoke bomb) is physically described and their anionic compositions are determined. Preblast (fuses and charges) samples and postblast residues of the different consumer fireworks were analyzed by CE in order to determine their anionic composition. Different types of chemical compositions in fuses and pyrotechnic charges were determined, although they were not related to any type of item. Additionally, several discrepancies were found between the analytical results and the declared item compositions. Regarding postblast residues, a huge variety of anions were identified and attributed to some unconsumed starting materials and different chemical reactions occurring during combustion.

Study of the suitability of DUO plastic bags for the storage of dynamites.

A comparative study on the retentiveness of two plastic bags (DUO and Royal Pack) has been carried out by gas chromatography with mass spectrometry detection. Two types of dynamites were packed in both plastic bags. The bags were placed into glass jars and headspace analyses were performed over 11 weeks to detect whether the volatile constituents of the dynamites were released from the bags. DUO plastic bags showed much better retentiveness than Royal Pack plastic bags. Ethylene glycol dinitrate (EGDN) was quickly detected in the headspace of the glass jars containing Royal Pack plastic bags after 1 week of storage. On the contrary, only a weak signal of EGDN, which was not detectable in the total ion chromatogram, was detected after 11 weeks of storage. Moreover, DUO plastic bags have shown less background signals than the Royal Pack bags, being the former bags much more suitable for the storage of dynamites.

Dynamite analysis by Raman spectroscopy as a unique analytical tool.

Apart from powerful explosives, dynamites are complex samples with an intricate analysis. These mixtures of compounds of diverse chemical nature present a challenge to the analyst, and as a result, several analytical techniques need to be applied currently for their analysis. Taking into account that presently there are almost no methods for dynamite analysis in the literature, it is crucial to develop analytical methods that could be applied for the analysis of these samples. This study introduces the use of Raman spectroscopy to analyze dynamites. Two different dynamites made up of ethylene glycol dinitrate and ammonium nitrate, among other minor components, were analyzed by Raman spectroscopy. First, confocal Raman spectroscopy allowed the identification of different components easily distinguished by eye (ammonium nitrate, ethylene glycol dinitrate, and sawdust). Then, Raman mapping was used to show the distribution of the main components throughout the dynamite mass. Finally, several minor components were identified after flocculation (nitrocellulose) or precipitation (sawdust, CaCO3, and flour). The results obtained demonstrate the huge potential of this technique for the analysis of such a complex and tricky sample.

Comparative analysis of smokeless gunpowders by Fourier transform infrared and Raman spectroscopy.

Fourier Transform Infrared (FTIR) and Raman spectroscopic techniques were used to perform a comparative study of the spectral profiles of single-base, double-base and triple-base smokeless gunpowders. Preliminary results based on visual comparison of the spectra point out that spectra obtained by both vibrational techniques were useful for a rapid identification of gunpowders containing dinitrotoluene as one of the major components and triple-base gunpowders. Additionally, the Raman spectra of gunpowders with diphenylamine in its primary composition showed a characteristic band, assigned to 2-nitro-diphenylamine, allowing the identification of this type of gunpowders. Further differentiation among the spectra of different types of smokeless gunpowders obtained by both vibrational spectroscopic techniques was investigated by discriminant analysis. Different analyses were applied to spectral data considering the different composition of gunpowders. The presence or absence of different compounds (such as dinitrotoluene, diphenylamine or dibutyl phthalate) or the type of gunpowder according to the number of active components (single-base or double-base gunpowder) has been taken into account. FTIR and Raman spectroscopy in combination with discriminant analyses were successful tools of forensic interest for the classification of gunpowders and the possible identification of unknown samples of gunpowders.

Why is methenamine detected in Goma-2 dynamites originally methenamine free? An interpretation of relevant forensic results.

After the train bombing in Madrid (Spain) on 11 March 2004, methenamine was detected in some of the specimens of Goma-2 ECO dynamite submitted to the forensic laboratories when analyzed by gas chromatography coupled with mass spectrometry detection (GC-MS). Methenamine is synthesized from formaldehyde and ammonia through a condensation reaction. However, neither methenamine nor any of these compounds were used to manufacture Goma-2 ECO dynamite. Four different experiments were designed in order to explain the presence of methenamine detected in the dynamite samples analyzed. In the first one, GC-MS was used to analyze the individual components of Goma-2 ECO provided by the manufacturer and the components mixed in a raw paste. Methenamine was detected in the manufacturer's ammonium nitrate and in the raw paste. The other experiments were designed to find the precursors sources for methenamine generation in Goma-2 ECO. Results revealed that these sources could be ammonium nitrate for ammonia and sawdust for formaldehyde. Under heating conditions, dynamite could produce these precursors, which could condense in the injection port of the GC-MS system and generate methenamine. However, methenamine was not always detected in these dynamites. This was explained by the existence of two opposite effects: (a) dynamite stability makes difficult that ammonium nitrate releases ammonia and (b) there is a gradual loss of formaldehyde in sawdust along the time. Both effects can prevent the formation of an amount of methenamine large enough to be detected.

Study of losses of volatile compounds from dynamites. Investigation of cross-contamination between dynamites stored in polyethylene bags.

The purpose of this work was to study the appropriateness of polyethylene bags for the preservation of explosive specimens. To this end, specimens of two types of dynamites, Goma-2 EC, containing nitroglycol (EGDN) and dinitrotoluene (DNT), and Goma-2 ECO, containing only EGDN, were placed individually inside bags and introduced into hermetically sealed glass jars, which were stored for a period of time. Losses of volatile compounds were studied by headspace analysis using gas chromatography coupled to mass spectrometry (GC-MS). The cross-contamination between dynamites was studied by using high performance liquid chromatography with mass spectrometry (HPLC-MS) to analyse the extracts obtained after a sequential solvent extraction of these specimens. Polyethylene bags permit the loss of volatile compounds since EGDN and DNT were detected in the headspaces of the jars. Moreover, cross-contamination between dynamites was also demonstrated since DNT content decreased in the dynamite containing this compound and increased in the dynamite that had not contained it.

New protocol for the isolation of nitrocellulose from gunpowders: utility in their identification.

In this work, a new approach for the isolation of nitrocellulose from smokeless gunpowders has been developed. A multistep solvent extraction method was needed to purify nitrocellulose contained in gunpowders. For single-base or double-base gunpowders six consecutive solvent extractions were selected: three extractions with methanol (to remove nitroglycerin, 2,4-dinitrotoluene, ethyl-centralite, diphenylamine, and diphenylamine derivatives); one extraction with dichloromethane (to remove colorants and plasticizers of organic nature); one extraction with methanol (to facilitate a final polar extraction); and one extraction with water (to remove ionic components) were necessary at 35 degrees C. For the triple-base gunpowder studied, eight solvent extractions were needed due to a high concentration of the water-soluble nitroguanidine was present. In addition to the same five initial phases used for the single-base and double-base gunpowders, three water extraction phases at a higher temperature (75 degrees C instead of 35 degrees C) were also needed. A final step to solubilize nitrocellulose in methyl ethyl ketone was used to remove inert components (mainly graphite). Nitrocellulose isolated from these propellants was characterized by Fourier-Transformed Infrared Spectroscopy (FTIR spectroscopy). The same FTIR spectra were observed for nitrocelluloses isolated from different types of gunpowders. A comparison of FTIR spectra of nitrocellulose samples of different nitration degree evidenced that the bands regions most affected by this factor were: 3600-3400cm(-1), corresponding to the stretching vibrations of residual hydroxyl groups; 1200-1000cm(-1), attributed to the valence vibrations nuCO of the glucopyranose cycle; and 750-690cm(-1), assigned to vibrations of the nitrate group. In both cases, the bands appearing in these regions were more pronounced in the spectra of nitrocellulose samples of low nitration degree.