Examination of black inkjet printing inks by capillary electrophoresis

Małgorzata Król; Agnieszka Kula; Renata Wietecha-Posłuszny; Michał Woźniakiewicz; Paweł Kościelniak

doi:10.1016/j.talanta.2011.12.025

Examination of black inkjet printing inks by capillary electrophoresis

Talanta. 2012 Jul 15:96:236-42. doi: 10.1016/j.talanta.2011.12.025. Epub 2012 Jan 2.

Authors

Małgorzata Król¹, Agnieszka Kula, Renata Wietecha-Posłuszny, Michał Woźniakiewicz, Paweł Kościelniak

Affiliation

¹ Laboratory for Forensic Chemistry, Faculty of Chemistry, Jagiellonian University, 3 Ingardena St., 30-060 Krakow, Poland.

PMID: 22817956
DOI: 10.1016/j.talanta.2011.12.025

Abstract

Counterfeiting of documents is a common phenomenon in the modern world. A large proportion of forgeries relates to inkjet printed documents. Hence there is an evident need to develop an effective and reliable method for the differentiation and identification of inkjet inks on questioned documents. The aim of the presented study was to investigate the possibility of applying micellar electrokinetic capillary chromatography (MECC) to forensic analysis of inkjet inks extracted from black and white printouts. In order to achieve the above aim, a capillary electrophoresis system equipped with a diode array detector was used. The separation was performed using a fused silica capillary (60/50cm total/effective length, 75μm i.d.) with a background electrolyte composed of 40mM sodium borate, 20mM SDS and 10% (v/v) acetonitrile (pH 9.5) at 25°C and 30kV. Ink samples were extracted from black inkjet printouts with the use of dimethyl sulphoxide (DMSO). Differentiation of inks was based on the number of significant peaks at different wavelengths, the relative migration times and the characteristic UV-Vis spectra. The electropherograms of the inks extracted from paper showed patterns which in most cases were distinctly different from each other. The greatest diversity of electrophoretic profiles was revealed for documents printed by Hewlett-Packard inkjet technology. A database of electrophoretic separation results of inks has been constructed for further forensic use.