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Chemistry LibreTexts

Pen Ink

Spectroscopic and Chromatographic Analysis of Pen Ink


To determine the color and composition of pen inks and inked writing found on documents pertinent to the case.


Collect a variety of ballpoint and felt tip pens and prepare documents with those pens. Assign pens and documents to the suspects and to the crime scene.


Extraction fluid and mobile phase: aqueous 0.005 M heptanesulfonic acid and acetonitrile mixed in 45:55 ratio.

Standard Reference Material



Visible spectrophotometry; liquid chromatography

Special equipment

UV-Vis spectrophotometer; pair of small-volume, 1-cm cuvettes; liquid chromatograph with C18 column and diode array detector; 2-mL chromatography vials with screw caps


For instructor (detailed); For student (brief)

Typical results

Visible spectra of felt tip and ballpoint inks; representative chromatograms of two (A and B) pen inks: 20-µL injection of liquid sample; C18 column; isocratic elution with 45:55 aqueous 0.005 M heptanesulfonic acid (pH = 4.7): acetonitrile, flowing at 0.3 mL/min.