Application of time of flight secondary ion mass spectrometry to the in situ analysis of ballpoint pen inks on paper

Results presented in this paper demonstrate that time of flight secondary ion mass spectrometry (TOF-SIMS) can be used for the analysis of ballpoint pen inks producing mass spectra that were highly characteristic of the constituent dyes and inorganic substances used in their formulations. Analysis was performed directly off the substrate (typically document paper) containing the ink with no interference from the background matrix. The resultant spectra were highly characteristic of the ink formulation and could be used to confidently discriminate between different inks. No extraction or complicated sample preparation was necessary which ensures the integrity of the document under examination. This is not only important in forensic applications but also indicates the potential for the application of this technique to the analysis of inks on documents of historical or archaeological significance. TOF-SIMS was also shown to be capable of analysing ink containing a mixture of dyes, initially separated by thin-layer chromatography, directly on the chromatographic material.