Analysis of Volatile Solvent Components in Ink Blot Samples Prepared by 84 Inks from 3 Common Brands of Ink-Jet Printers by GC-MS

A method was established to analyze the volatile solvent components in 84 ink blot samples prepared by 84 inks from 3 common brands of ink-jet printers by GC-MS, and the solvent components in different inks were classified and summarized. A4 paper was printed with original inks of different models of A and B brand printers, and ink drops blot of different models of C brand printer inks were collected with A4 paper. Samples were taken with a hole punch the next day, and volatile solvent components were extracted with methanol solution containing 5 mg·L^-1 ethyl benzoate, and the extract was introduced into the GC-MS without split flow. The solvent components were separated by temperature programmed on an HP-INNOWAX chromatographic column, and then detected by mass spectrometer equipped with electron impact ion source (EI) for qualitative analysis with retention time and qualitative ions. The results showed that 12 solvents in 84 ink blot samples obtained were diethylene glycol, triethylene glycol, 2-pyrrolidinone, 1-(2-Hydr-oxyethyl)-2-pyrrolidone, glycerol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, trimethylol propane, 1,6-hexanediol, 2-methyl-1,3-propanediol, 1,2-hexanediol, triethylene glycol monobutyl ether. The composition of volatile solvents in samples of different brands or different models of the same brand had certain characteristic, which can distinguish the ink blot samples of different brands and even models and provide technical reference for the identification of the authenticity of ink-jet printed documents in judicial identification.