Advances in the forensic analysis and dating of writing ink

23 Oct

the Secret Service's TLC library consists of ~8,500 inks).It's an important technique, however the process can't be automated.The researchers, with Florida International University, compared four Laser Induced Breakdown Spectroscopy (LIBS) systems – three commercially available and one built by the researchers – to the more complex and costly Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) system that is used in forensic analysis.

All of the systems tested work by laser ablation, which is a progressive and superficial destruction of a material by melting, fusion, sublimation, erosion, and explosion, the researchers said.

Differences in the samples suggested that the questioned entry was made on a separate occasion, possibly to cover insider trading violations.

In their articles in this month's Forensic Science Communications, FBI research chemists James Egan, Jason Brewer, and Kristin Hagan demonstrate advances in the forensic analysis of ballpoint pen inks--both for black inks and blue inks. A process called thin-layer chromatography (TLC) is normally used.

The researchers also noted that as papers and inks are constantly being changed in the marketplace, document examiners have an increased interest in finding alternative and complementary methods of analysis.

For instance, they said, gel pen inks have become a prominent type of ink in forensic document examinations but present a challenge because gel inks are difficult to analyze by conventional techniques. A total of 400 different types of ink were analyzed and more than 97 percent of writing inks and up to 100 percent of printing inks were correctly “discriminated” by the LIBS system.