The analysis of forensic samples using laser micro-pyrolysis gas chromatography mass spectrometry

Laser micropyrolysis gas chromatography-mass spectrometry is used for the a nalysis of paint, photocopier toner, and synthetic fiber materials to test the forensic potential of this emerging technology. It uses a laser micropr obe to selectively target very small parts of the materials for GC-MS analy sis. Whereas the paint and the toner samples were amenable to direct laser pyrolysis, the synthetic fibers proved transparent to the 1064 nm laser rad iation. The difficulty with the fibers demonstrates that a specific laser w avelength may not be appropriate for all types of materials. Nevertheless, the fibers were able to be indirectly pyrolyzed by impregnation in a strong ly absorbing graphite matrix. A vast array of hydrocarbon pyrolysates was d etected from the different materials studied. Unique product distributions were detected from each sample and in sufficient detail to facilitate indiv idual molecular characterization (i.e., molecular fingerprinting). The inte grity of the laser data were confirmed by comparison to data obtained from the same samples by the more conventional pyroprobe pyrolysis GC-MS method. The high spatial resolution and selectivity of the laser method may be adv antageous for specific forensic applications, however, further work may be required to improve the reproducibility of the data.