Evaporation of Volatile Solvents to Characterize the Aging of Inkjet Inks for Forensic Purposes Studied by Thermal Microdesorption and Gas Chromatography-Mass Spectrometry (GC-MS)

Evaporation of various solvents in inkjet printouts on paper text was studied by thermal microdesorption in combination with gas chromatography-mass spectrometry (GC-MS). Inks from several models of printers and from several manufacturers were studied. The thermal microdesorption at 200 & DEG;C as well as the fractionated microdesorption at three temperatures were employed. The following solvents were found in the examined printouts: diethylene glycol, glycerol, 2-pyrrolidinone, 2-ethyl 2-hydroxymethyl 1,3-propanediol, triethylene glycol, butoxyethoxyethanol, and 1,5-pentanediol. On aging, the quantity of these solvents decreased rapidly and generally could be detected in the prints only for several months after the deposition. In prints more than two years old, no or only traces of volatile solvents were found by this method. This is important for forensic analysis of documents produced by inkjet printers. The method can reveal that a document is fresh and not as old as given in the questioned document.