There is a need in many industries and government functions to identify the source of origin for various materials. For example, the food industry needs to ensure that the claimed source of some of the food products (e.g. coffee, spices) are in fact legitimate due to the variation of quality from different source locations world-wide. Another example is to identify the source country for imported commodities going through Customs so as to assess the correct tariff which varies depending on the source country. Laser Induced Breakdown Spectroscopy (LIBS) holds promise for being a field-portable tool for rapid identification of the country of origin of various materials. Recent research at Towson University has identified the elemental markers needed for discrimination of select spices back to their country of origin using wavelength dispersive X-ray fluorescence (WDXRF). The WDXRF device, however, is not particularly suitable for convenient and fast field analysis. We are extending this study to evaluate the potential of a benchtop commercial LIBS device that could be located at ports of entry and to compare its performance with WDXRF. Our initial study on the spice cumin has demonstrated that discriminant function models can not only be created with 100% separation between the 4 countries of origin (China, India, Syria, and Turkey), but also when tested they show 100% correct matching to the country of origin. This study adds to the growing number of publications that indicate the power of LIBS elemental fingerprinting for provenance determinations.
There continues to be a need for improved technology to be used in theater to quickly and accurately identify the person who shot any weapon during a terrorist attack as well as to link a suspect to the actual weapon fired during a crime. Beyond this, in areas of conflict it would be desirable to have the capability to establish the source country for weaponry and ammunition. Gunshot residue (GSR) analysis is a reasonably well-studied technology area. Recent scientific publications have reported that the residues have a rich composition of both organic and inorganic compounds. For the purposes of identifying the manufacturer or country of origin for the ammunition, the inorganic components of GSR appear to be especially promising since their presence in the propellant and primer formulations are either specific to a given chemical formula, or they represent impurities in the manufacturing process that can be unique to a manufacturer or the source country for the chemicals used for propellants and primers. The Laser Induced Breakdown Spectroscopy (LIBS) technology has already demonstrated considerable capability for elemental fingerprinting, especially for inorganic/metallic components. A number of reports have demonstrated LIBS capability in forensics for matching materials such as inks, fabrics, paper, glass, and paint. This work describes the encouraging results of an initial study to assess a new commercial field-portable (battery operated) LIBS system for GSR analysis with gunshot residues having been collected from inside cartridge casings from 3 different ammunition manufacturers.