Gunshot residues: screening analysis by laser-induced breakdown spectroscopy

Journal of the Brazilian Chemical Society

Paim, Ana Paula S.¹  Universidade Estadual de Campinas, Campinas, Brazil¹  Pimentel, Maria Fernanda¹  Silva, Maria José¹  Universidade Federal de Pernambuco, Recife, Brazil¹  Pasquini, Celio¹  Cortez, Juliana¹  Superintendência Regional em Pernambuco, Recife, Brazil¹  Honorato, Ricardo S.¹ 

关键词: laser-induced breakdown spectroscopy;    gunshot residues;    SIMCA;    screening analysis;    LIBS;   

DOI  :  10.1590/S0103-50532009001000017

学科分类：化学（综合）

来源: SciELO

【 摘 要 】

Laser induced breakdown spectroscopy (LIBS) is further developed for the detection of gunshot residue (GSR) on the hands of a suspected shooter. To develop the procedure, 114 samples were obtained by pressing a small piece of adhesive tape against the dorsal region of the hands of non-shooters, of shooters just after firing a weapon, and of shooters after washing their hands with soap and water. The tapes were analyzed directly in a time-resolved echelle based LIBS system, assembled in the laboratory, and 20 single laser pulses, spread uniformly on the tape surface, were shown to be enough to ensure the detection of true positives. The spectra obtained by LIBS from the tape present a signature with emission lines that are attributed to barium and lead. After the spectral data was submitted to a pattern recognition method SIMCA (Soft Independent Modeling of Class Analogy), shooters and non-shooters were corrected classified. The method based on LIBS and SIMCA has been demonstrated to be non-destructive of crime evidence and enabled discrimination between the samples collected from non-shooter volunteers and shooter volunteers before and after washing their hands.

【 授权许可】

Unknown