Source Determination of Red Gel Pen Inks using Raman Spectroscopy and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy combined with Pearson's Product Moment Correlation Coefficients and Principal Component Analysis |
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Authors: | Muhammad Naeim Mohamad Asri B.Sc. Wan Nur Syuhaila Mat Desa Ph.D. Dzulkiflee Ismail Ph.D. |
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Affiliation: | 1. Forensic Science Program, School of Health Sciences, Universiti Sains Malaysia, Health Campus, Kubang Kerian, Kelantan, Malaysia;2. Forensic Science Program, Department of Diagnostics and Allied Health Sciences, Faculty of Health Science, Management and Science University, Shah Alam, Selangor, Malaysia |
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Abstract: | The potential combination of two nondestructive techniques, that is, Raman spectroscopy (RS) and attenuated total reflectance–fourier transform infrared (ATR‐FTIR) spectroscopy with Pearson's product moment correlation (PPMC) coefficient (r) and principal component analysis (PCA) to determine the actual source of red gel pen ink used to write a simulated threatening note, was examined. Eighteen (18) red gel pens purchased from Japan and Malaysia from November to December 2014 where one of the pens was used to write a simulated threatening note were analyzed using RS and ATR‐FTIR spectroscopy, respectively. The spectra of all the red gel pen inks including the ink deposited on the simulated threatening note gathered from the RS and ATR‐FTIR analyses were subjected to PPMC coefficient (r) calculation and principal component analysis (PCA). The coefficients r = 0.9985 and r = 0.9912 for pairwise combination of RS and ATR‐FTIR spectra respectively and similarities in terms of PC1 and PC2 scores of one of the inks to the ink deposited on the simulated threatening note substantiated the feasibility of combining RS and ATR‐FTIR spectroscopy with PPMC coefficient (r) and PCA for successful source determination of red gel pen inks. The development of pigment spectral library had allowed the ink deposited on the threatening note to be identified as XSL Poppy Red (CI Pigment Red 112). |
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Keywords: | forensic science Raman spectroscopy ATR‐FTIR spectroscopy Pearson's product moment correlation principal component analysis gel pen inks |
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