Changes in composition of ballpoint pen inks on aging in darkness

Area of Science:

• Forensic Science
• Analytical Chemistry

Background:

• Determining the relative age of ink entries is crucial in forensic document examination.
• Existing methods may be limited in scope or applicability.

Purpose of the Study:

• To present a novel method for comparing the relative age of ballpoint pen ink entries on documents stored in darkness.
• To establish a reliable technique for forensic casework involving undated or disputed documents.

Main Methods:

• Ink samples were extracted from documents.
• High-performance liquid chromatography (HPLC) was employed to analyze ink composition.
• Ternary diagrams were constructed using Crystal Violet, Methyl Violet, and Tetramethyl Para Rosaniline dyes to track aging.

Main Results:

• Chemical composition changes in inks were observed during aging.
• These aging-induced changes mirrored those caused by light and heat exposure.
• The method demonstrated applicability for relative dating of ink entries from the same pen.

Conclusions:

• The proposed HPLC method provides a viable approach for the relative dating of ballpoint pen inks.
• The technique is particularly useful for documents with multiple entries from the same pen, such as diaries and notebooks.
• The method's limitations include inapplicability after prolonged exposure to light or heat.