Analysis of explosive residues in human fingerprints using optical catapulting–laser-induced breakdown spectroscopy

Abstract

Optical catapulting in combination with laser induced breakdown spectroscopy (OC-LIBS) is a new developing technique that has been effectively tested for the analysis of solid aerosols. In the present work OC-LIBS has been used to analyze explosive residues in human fingerprints left on glass surfaces in the form of solid aerosols. Experimental conditions such as the temporal acquisition delay, the distance from the surface and the interpulse delay time between lasers are studied. Explosives residues (TNT, DNT and MNT) and confusant materials (oil and Bermuda grass smut spores) were identified by OC-LIBS. Chemical images generated by OC-LIBS provided visual information on the spatial distribution of the explosive residue in the fingerprints. Advantages of OC-LIBS over conventional LIBS include the absence of contamination of the specimen analyzed and the freedom from spectral contribution of the substrate where the sample was placed.