Microdestructive Capillary Electrophoresis Analysis of Ink Samples

A novel microdestructive capillary electrophoresis (CE) method for the analysis of blue pen ink strokes has been published in the Journal of Chromatography A.¹ The analysis of pen inks can be challenging because ink compositions are usually under patent, the samples are small, and inks can degrade over time.

CE has previously given promising results when applied to the analysis of questionable documents, according to coauthor Matías Calcerrada. He told The Column: “We believe that CE could be an efficient analytical technique for casework involving questioned documents, due to advantages such as its minimal sample consumption and ability to detect and quantify different analytes found in ink formulations.”

The team developed a microdestructive sample treatment method using a scalpel to scratch 0.3 mg of an ink stroke from paper, prior to analysis using CE with a DAD detector. Samples of ink from 34 blue pens from different technologies (ballpoint, rollerball, marker) with different composition (gel, water-based, oil-based) were analyzed to discriminate between different technologies and inks. Calcerrada said: “We believe that the results published demonstrate that the method could be applied in forensic casework after applying other non-destructive methodologies, which are always recommended before destroying the sample.” - B.D.

Reference
1. Matías Calcerrada, Journal of Chromatography A1400, 140–148 (2015).

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