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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Forensic analysis of hand-written documents using laser-induced breakdown spectroscopy (LIBS) and chemometrics

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Author(s):
Hilario, Felipe Ferri [1] ; Lima de Mello, Matheus [1] ; Pereira-Filho, Edenir Rodrigues [1]
Total Authors: 3
Affiliation:
[1] Univ Fed Sao Carlos, Dept Chem, Grp Appl Instrumental Anal, BR-13565905 Sao Carlos, SP - Brazil
Total Affiliations: 1
Document type: Journal article
Source: ANALYTICAL METHODS; v. 13, n. 2, p. 232-241, JAN 14 2021.
Web of Science Citations: 0
Abstract

With the use of Laser Induced Breakdown Spectroscopy (LIBS), fast and semi non-destructive elemental analysis of ball-point pen writings has been performed directly from paper surfaces, aiming to obtain maximum differentiation between pens with a minimum number of pulses. The instrumental variables, the delay time, laser pulse energy and number of pulses per point, were evaluated through factorial design and optimum values were obtained through a quadratic regression model. Several atomic emission lines were tested as fingerprints in order to improve the differentiation between the tested inks and the range of 212-228 and 324-328 nm, which corresponds to Cu emission, demonstrated to be the best alternative as a discriminatory factor for two pens of the same color. However, the background contribution of cheque paper limited the multielement profile of the technique. Seventeen different pens were analyzed. Principal Component Analysis (PCA) treatment was used to classify the samples in clusters and to assemble hyperspectral images in order to obtain visual differentiation of the inks in a scores map. The results obtained by LIBS analysis were verified by microwave-assisted digestion of inks and analysis by ICP OES. Lastly, a real situation test was conducted where a forged document was analyzed by the proposed methodology as an alternative to distinguish between two inks of the same color, originating from different pens. For this proof of concept study, seventeen samples were evaluated, but further studies related to heterogeneity between pulses and samples should be carried out. (AU)

FAPESP's process: 19/24223-5 - Calibration in Laser-Induced Breakdown Spectroscopy (LIBS): alternatives, challenges, proposals comparison and proposition of a universal procedure
Grantee:Edenir Rodrigues Pereira Filho
Support Opportunities: Regular Research Grants