Identification of Luminescent Markers for GunshotResidues: Fluorescence, Raman Spectroscopy, and Chemometrics

Gunshot residue (GSR) is an evidence of major importance in firearm-related crimes. The recent introduction of non-toxic ammunition has made impossible the characterization of GSR particles by the current methods employed by forensic experts. To overcome this drawback, the introduction of luminescent markers was proposed, allowing on site visual detection of luminescent gunshot residue (LGSR) at the crime scene. Three different luminescent markers coordinated with europium, for specific and selective encoding of ammunition have been proposed. To promote a variety of versatile tools for GSR analysis, spectroscopic techniques combined with chemometric methods can be applied to achieve a reliable, fast and non-destructive means to identify LGSR and discriminate among the different markers. Luminescence (emission and excitation), normal and resonance Raman spectroscopies associated with Principal Component Analysis (PCA) and Partial Least Squares - Discriminant Analysis (PLS-DA) were evaluated. The classifica...