Differentiation and dating of gel pen ink entries on paper by laser desorption ionization- and quadruple-time of flight mass spectrometry

The approaches for differentiation and dating of gel pen ink entries have been investigated by laser desorption ionization-time of flight mass spectrometry (LDI-TOF-MS) and high performance liquid chromatography-quadruple-time of flight mass spectrometry (HPLC-Q-TOF-MS). 45 kinds of black and blue gel pen ink entries were differentiated individually by the profiles of their LDI-MS spectra. The dye components in the black and blue ink entries have been identified by thin layer chromatography and HPLC-Q-TOF-MS methods. The degradation processes of the dye components in the ink entries under various aging conditions have been probed by LDI-MS approach. The results showed that the variations of relative intensities for the main dye components have a close relationship with aging time, and the degradation of the main dye components were significant under natural storage conditions, which can provide important evidences for dating of the ink entries on paper.

► The gel pen ink entries have been differentiated by LDI-TOF-MS.
► The dye components of the ink entries have been identified by Q-TOF-MS.
►  Degradation of the dye components in ink entries has been investigated by LDI-MS.
► Dating method for the ink entries were developed based on degradation of the dyes.