Coupling ATR-FTIR Spectroscopy and Chemometric Analysis for Rapid and Non-Destructive Ink Discrimination of Forensic Documents

Abstract

The large increase of global counterfeit documents urges the need to explore novel methods for forensic examination toward efficient discrimination of forged and authentic documents. The attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy holds great promise for reliable chemical analysis. The chemometric analysis such as the principal component analysis (PCA) provides a very powerful analytical tool, especially when dealing with complicated multi-component spectral data sets. In this paper, we demonstrate a promising approach for the rapid and non-destructive discrimination of writing-pen inks using the ATR-FTIR spectroscopic technique coupled with the PCA. A variety of writing pens of different sorts were collected and the ink samples were applied onto one type of photocopier paper. The ATR-FTIR spectra of ink samples were measured triply over two spots yielding six spectra for each studied ink. The obtained FTIR spectra were compared to confirm the repeatable spectral profile. The ATR-FTIR spectral results obtained for the different inks indicate the presence of triarylmethane dye as a basic colorant in the studied writing-pen inks. Adopting the visual analysis of the FTIR spectra of the different inks, a relatively low discrimination power of only 72 % could be achieved which limits routine FTIR analysis in forensic documents examination. Interestingly, the coupling of the PCA as a multivariate chemometric technique with FTIR resulted in much improved spectral discrimination. The PCA score plot of the first two principal components (PC1 and PC2) using the spectral data of the 33 pen ink samples resulted in a significantly higher discrimination power of 100 % with all data points showing separately, indicating successful discrimination of all ink samples. Such high discrimination power is highly desirable in forensic examination of question documents to eliminate errors leading to poor ink identification due to human factors. The inks discrimination was achieved using samples of inks directly applied onto paper without any sophisticated sample preparation or processing. This ATR-FTIR/PCA analytical approach may serve as a potential method for reliable, and non-destructive forensic documents examination aimed at rapidly identifying a forgery.

Chemical and Imaging Analysis of Questioned Document Paper by FTIR, ICP and Video Spectral Comparator (VSC) for Forensic Discrimination

“…The characteristics bands due to −CH 2 , −CH−, −OH and C−O were detected at 1422, 1311, 1030 and 871 cm −1 , which are assigned to the cellulose. The peaks at 871 and 711 cm −1 are corresponding to the C−O stretching and O−C−O bending, which indicate the presence of calcium carbonate filler, respectively [37–39] . Moreover, asymmetric C−O at 1424 cm −1 showed the presence of CaCO 3 [40] .…”

Utilization of iron fillings solid waste for optimum biodiesel production

“…The absorption peaks at the wavelengths of 460.9, 509.1, and 616.2 cm −1 correspond to the Fe-O stretching mode of Fe 2 O 3 and the vibration of Fe-O in the rhombohedral lattice of hematite which is an important characteristic of the crystalline of α-Fe 2 O 3 compound ( Lassoued et al, 2017b ; Jing and Wu, 2004 ). The absorption peak at the wavelength of 870.8 may be due to the presence of an oxygen-containing function group of calcite ( Gawad et al, 2022 ) or aromatic C-H stretching vibration because of the presence of organic impurities in the sample ( Mansour et al, 2022 ).…”

“…Frontiers , 2004). The absorption peak at the wavelength of 870.8 may be due to the presence of an oxygen-containing function group of calcite (Gawad et al, 2022) or aromatic C-H stretching vibration because of the presence of organic impurities in the sample (Mansour et al, 2022).…”

Validated ATR-FTIR Method For Quantitative Simultaneous Estimation of Terbutaline Sulfate, Guaiphenesin and Bromhexine Hydrochloride, in Bulk and Pharmaceutical Dosage Form.

“…ATR-FTIR is gaining much interest as an environmental friendly analytical technique, for qualitative and quantitative estimation of chemical substances in the of fields chemistry, pharmacy, forensics, and food analysis, among others experimental sciences., e.g. Spectroscopy Analysis of Saliva for Breast Cancer Diagnosis [6] also in rapid Non-Destructive Ink Discrimination of Forensic Documents [7] for the of biopharmaceuticals [8] quantification of water content in deep eutectic solvents, [9] and other liquids such as milk [10], honey, [11], etc. The ATR sampling allows for quick and easy analysis without the need for time-consuming sample preparation.…”