Dangers of dynamite storage: Cross-contamination of evidence bags from Madrid ...

The devastating Madrid train bombings in March 2004 killed almost 200 people and injured nearly 2000 and, despite the best efforts of the authorities, the attacks remain unattributed. The type of explosive used for this attack seems to point to the Basque terrorist organisation ETA, although Al-Qaeda is thought to have claimed responsibility.

The forensic teams identified traces of nitroglycerin and dinitrotoluene (DNT) in the explosion debris. These are components of the explosive known as Titadyn, a dynamite which has been used in many Spanish terrorist bomb attacks.

The debris from the Madrid train bombings was collected in polyethylene bags and sealed before transportation to a lab where it was stored for three years before analysis. This type of bag was considered the best available option to avoid losses of vapours from the bags compared with metal paint cans and glass jars.

However, recent studies have suggested that volatile components can escape from polyethylene bags, compromising the evidence in forensic cases. The bags from the train bombings were kept alongside further plastic bags containing Titadyn and other types of dynamite from different cases, raising the possibility of cross-contamination between the different samples.

These concerns have now been addressed by Spanish scientists who have undertaken a study of the Goma-2 EC and Goma-2 ECO dynamites, two common dynamites that are manufactured in Spain. Goma-2 EC contains DNT, nitrocellulose and ethyleneglycol dinitrate (EGDN) whereas Goma-2 ECO has no dinitrotoluene, in line with recent European legislation on toxic nitrotoluenes.

Their results were reported by senior reporter Carmen Garcia-Ruiz and colleagues from the Police Sciences University Research Institute at the University of Alcala, and the Criminalistics Service of Guardia Civil in Madrid.

In the first instance, the researchers examined losses of EGDN from Goma-2 ECO which was stored in an official polyethylene carrier bag fitted with a rubber seal designed to prevent the transfer of volatile compounds in either direction, in or out of the bag.

Following storage under varying conditions in glass jars, the compositions of the jar headspaces were measured by GC/MS and the concentrations of EGDN remaining in the dynamites were measured after solvent extraction by HPLC with mass spectrometric detection.

For LC/MS, the analytes were separated on a silica gel column with a gradient of methanol in water. The eluting compounds were analysed by atmospheric pressure chemical ionisation in negative-ion mode. LC/MS was preferred to HPLC-DAD, due to a better detection limit for 2,6-DNT: of 3 ng/mL compared with 300 ng/mL.

Complementary High-Performance Liquid Chromatography – Mass ...

Determination of Additives in Polymers and Rubbers .

Gas chromatography (GC) is only useful for analysing some low molecular weight polymers, other techniques such as high-performance liquid chromatography (HPLC) and particularly size exclusion chromatography (SEC) are applicable to the separation and/or fractionation of polymers prior to the detailed determination of their nature, amount and structure by mass spectroscopy (MS).  Additionally controlled pyrolysis of the polymer followed by HPLC or GC often supplies useful information on the composition, microstructure and thermooxidative degradation of polymers.

One of the limitations of GC and consequently of GC-MS is that in many cases polymers or their oxidation products are insufficiently volatile to be separated on a gas chromatography column operating even at their maximum temperature range.  As a consequence of this, there is a growing interest in applying HPLC which is not subject to this temperature limitation, to the elucidation of polymer structure and degradation mechanisms.  Some applications of this technique are:

Analysis of Polymer Blends

Adsorption/desorbtion chromatography linked to mass spectroscopy has been used to separate binary components blends such as polystyrene with polymethacrylate or polystyrene with polyvinylacetate.  This technique has been used to separate up to four component blends such as polystyrene, polymethylmethacrylate, polyvinyl alcohol and polyethylene oxide.

Toxic organic vapors in the workplace

Toxicology, a case-oriented approach

Medical toxicology

Guide to ASTM Test Methods for the Analysis of Petroleum Products and Lubricants

CRC handbook of chromatography