Spectroscopic techniques and chemometrics for ink analysis: Document analysis application

Area of Science:

• Forensic Science
• Analytical Chemistry
• Spectroscopy

Background:

• Document forgery is a significant challenge in forensic investigations.
• Reliable methods are needed to authenticate documents and identify counterfeit items.
• Spectroscopic techniques offer non-destructive analysis for material characterization.

Purpose of the Study:

• To develop and validate a combined spectroscopic and chemometric methodology for detecting falsified documents.
• To assess the discriminatory power of UV-Vis and FTIR-ATR spectroscopy for ballpoint pen ink analysis.
• To demonstrate the application of the methodology in real-world forensic scenarios, including limited sample analysis.

Main Methods:

• Application of UV-Vis and FTIR-ATR spectroscopy combined with Principal Component Analysis (PCA).
• Analysis of eleven ballpoint pen ink samples (black, blue, red) from three brands in Türkiye.
• Development of a dried sample preparation technique to enhance FTIR-ATR sensitivity for small samples.

Main Results:

• FTIR-ATR spectroscopy exhibited higher discriminative power than UV-Vis for identifying ink brands.
• UV-Vis spectroscopy effectively distinguished inks based on color.
• The methodology successfully classified ballpoint inks and identified a falsified old-dated check sample.
• FTIR-ATR analysis confirmed forgery detection from minimal sample amounts.

Conclusions:

• The proposed methodology, integrating UV-Vis and FTIR-ATR spectroscopy with chemometrics, is effective for classifying and identifying ballpoint inks.
• The technique is valuable for forensic applications, particularly in detecting document forgery from limited sample quantities.
• This comprehensive approach is applicable even in resource-limited laboratories with basic spectroscopic capabilities.