Forensic Identification of Explosives by Mass Spectrometry and Allied Techniques.

In forensic analysis of explosives, analytical methods are required that combine good separation characteristics with highly specific and sensitive detection. Two novel techniques, liquid chromatography/mass spectrometry (LC/MS) and tandem mass spectrometry (MS/MS) have such specifications. These are now well-established analytical techniques for separation and identification of mixtures and for trace analysis of selected components. The principles and instrumentation of LC/MS and MS/MS are described, as well as their applications, in forensic identification of explosives residues and detection of hidden explosives.

Metabolic studies of explosives 6. Electron impact and chemical ionization mass spectrometry of metabolites of 2,4-dinitrotoluene.

A series of metabolites of 2,4-dinitrotoluene have been synthesized and analysed by electron impact and chemical ionization mass spectrometry. Identification characteristics of these metabolites by their mass spectra have been determined. Differentiation of isomers is made possible by electron impact ions which are characteristic to the position of the methyl group with regard to the nitro group and to the position of the carboxylic acid group with regard to the nitro group. Metabolites containing an acetyl amino group are characterized by an [M - COCH2]+. electron impact ion.

Applications of liquid chromatography-mass spectrometry in metabolic studies of explosives.

Liquid chromatography-mass spectrometry was used for the detection and identification of metabolites of 2,4,6-trinitrotoluene (TNT) in urine and blood. The metabolites were found in the urine of rats and in the blood of rabbits fed with TNT, in the urine of rats exposed to TNT by skin absorption and in the urine of TNT munition workers. The detected metabolites, formed by reduction processes, included 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,4-diamino-6-nitrotoluene and 2,6-diamino-4-nitrotoluene, in addition to untransformed TNT.

Metabolic studies of explosives. 5. Detection and analysis of 2,4,6-trinitrotoluene and its metabolites in urine of munition workers by micro liquid chromatography/mass spectrometry.

Metabolites of 2,4,6-trinitrotoluene (TNT) were found in the urine of a group of TNT munition workers. The urine extracts were analysed by micro liquid chromatography/mass spectrometry. The metabolites found included 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene, 2,4-diamino-6-nitrotoluene, 2,6-diamino-4-nitrotoluene and untransformed TNT. The detection limit of the metabolites in urine was 0.1 ng/ml for 20 ml urine samples.

Identification of urinary metabolites of 2,4,6-trinitrotoluene in rats by liquid chromatography-mass spectometry.

Metabolites of 2,4,6-trinitrotoluene (TNT) were found in the urine of rats fed with TNT. The urine extracts were analysed by liquid chromatography-mass spectrometry (LC-MS). Metabolites found included TNT itself as well as 2-amino-4,6-dinitrotoluene, 4-amino-2,6-dinitrotoluene and 2,4-diamino-6-nitrotoluene, indicating that reduction processes are responsible for the formation of these metabolites.

Metabolic studies of explosives. II. High-performance liquid chromatography-mass spectrometry of metabolites of 2,4,6-trinitrotoluene.

A series of metabolites of 2,4,6-trinitrotoluene were studied by combined high-performance liquid chromatography-mass spectrometry. These metabolites are formed mainly by oxidation and reduction processes. Separations were done on a C8 reversed-phase column, using acetonitrile-water at various relative concentrations as mobile phases, followed by ultraviolet and on-line mass spectrometry with a direct liquid insertion probe liquid chromatograph-mass spectrometer interface. The mass spectra obtained were chemical-ionization spectra with the mobile phase as reagent. Mass spectra obtained included mainly reduced ions, adduct ions and typical fragment ions. The combination of high-performance liquid chromatographic separation with on-line mass spectrometry was found to be a suitable method for the identification of the investigated metabolites.

Metabolic studies of explosives. 1--EI and CI mass spectrometry of metabolites of 2,4,6-trinitrotoluene.

A series of metabolites of trinitrotoluene (TNT) have been synthesized and analysed by electron impact (EI) and chemical ionization (CI) mass spectrometry. Identification characteristics of these metabolites by their mass spectra have been determined. Differentiation of isomers is made possible by EI ions which are characteristic of the position of the methyl with regard to the nitro groups.

Screening of organic acids in urine by chemical ionization mass spectrometry.

A method has been developed for qualitative screening of carboxylic acids in human urine. The method uses direct chemical inoization mass spectrometry with isobutane as reagent gas. The carboxylic acids are separated from the urine samples by ion exchange. Normal carboxylic acid profiles have been determined and are compared with the profiles of patients suffering from certain metabolic disorders.

Diagnosis of disorders in amino acid methabolism by chemical ionization mass spectrometry.

A semi-quantitative method has been developed for rapid determination of amino acids and other nitrogenous compounds in human urine. The method uses direct chemical ionization mass spectrometry with isobutane as reagent. The nitrogenous compounds are separated from the urine samples by ion exchange. Disorders in amino acid metabolism have been determined by this method in patients suffering from phenylketonuria, cystinuria and maple-syrup urihe disease.