Forensic Characterization of Gel Pen Inks with Thin Layer Chromatography and Ultraviolet Spectroscopy Technique

Abstract Background: Using a comprehensive approach that combines Thin Layer Chromatography (TLC), UV-visible spectroscopy, and Adobe Photoshop image manipulation, this study aims to authenticate and identify Gen gel pens. Aim and Objectives: The principal objective is to describe gel pen ink compositions and develop an authentication process for them. Thirty gel pen ink samples total—ten of each for the colors red, black, and blue—are the subject of the study. Goals include applying Adobe Photoshop for improved visual differentiation and using TLC and UV-visible spectroscopy for preliminary characterization. Materials and Methods: To characterize the compositions of thirty gel pen ink samples, Thin Layer Chromatography and UV-visible spectroscopy were applied. To improve the visuals, images were turned upside down and their brightness was changed using Adobe Photoshop. Gel pen ink matching was tested in a blind trial that combined analytical findings with Photoshop-enhanced visual differentiation. Results: 76% of samples could be distinguished clearly, according to analytical data, and 40% of samples showed UV absorption at 237.5 nm regardless of the colour of the ink. Remarkably, on the UV Visible Spectrum, 76.6% showed distinct peaks. A major factor in the ability to visually distinguish ink samples was Adobe Photoshop. Different ink samples could be identified using UV-visible spectroscopy peak variations; 23.3% of the samples showed nonspecific peak patterns that could be seen in photos that had been Photoshopped. Conclusion: The combined findings provide insightful information about gel pen ink differentiation and suggest a possible approach for model identification and authentication. This method combines Adobe Photoshop image manipulation with analytical methods like TLC and UV-visible spectroscopy.