Discrimination of Ballpoint Pen Inks for Document Examination: A Forensic Approach using Uv-Vis, FTIR, and HPTLC Techniques

Introduction/Objective: Documents are widely used in financial transactions, business operations, identity verification, and information dissemination, making them targets for forgery and alteration. Ink analysis, therefore, plays a crucial role in forensic document examination, particularly for ballpoint pens, whose complex ink formulations can make analytical differentiation challenging. This study focuses on ballpoint pen inks commonly used in Ghana, aiming to characterize their chemical compositions, differentiate between ink types, assess changes over time, and establish reference data for forensic comparison. A combination of UV-Vis spectroscopy, FTIR spectroscopy, and HPTLC was employed to evaluate both direct and extracted ink samples and to determine the discrimination potential of each technique. Methodology: Fifty-six ballpoint pens (32 blue, 10 black, 9 red, 5 green) of various brands were collected across Ghana. UV-Vis analysis was performed on methanol-extracted inks. FTIR spectra were obtained directly from 1cm x 1cm marked paper areas using ATR. For HPTLC, handwritten samples were cut and extracted with 0.5 mL methanol; 5μL of each extract was applied to silica plates developed in ethyl acetate: ethanol: water (7:3:2) and visualized under white and UV light. Results: UV-Vis identified crystal violet in blue and black inks, methyl yellow in black inks, rhodamine dyes in red inks, and phthalocyanine dyes in green inks. Discrimination potential exceeded 90% for most colors across direct and extracted samples. HPTLC differentiated inks based on band patterns and Rf values and detected changes over one month of heat exposure. FTIR revealed characteristic functional groups and achieved discrimination potentials of 91% - 100%. Discussion: This study establishes reference data for ballpoint pen inks in Ghana and demonstrates the strong discriminatory capability of combining UV-Vis, HPTLC, and FTIR techniques. Conclusion: The study shows that UV-Vis spectrophotometry, HPTLC, and FTIR spectroscopy together provide reliable identification of inks, which can be useful for forensic document examination.