Organic and inorganic discrimination of ballpoint pen inks by ToF-SIMS and multivariate statistics

Surface analysis by ToF-SIMS analysis of ballpoint pen ink markings was performed for discrimination. ToF-SIMS provided non-destructive analysis of ink's organic and inorganic components directly off paper with no interference from the paper substrate. Organic and inorganic information were collected simultaneously and processed with PCA, discriminating 41 out of 45 pairs (91%) of pens analysed. Minimal sample preparation and analysis time, the simultaneous acquisition of organics and metals, and ability to analyse trace amounts gives this technique advantages over others currently utilised in the forensic field. Simultaneous acquisition of organics and inorganics has not been presented before for the characterisation of these materials. It was indicated that pens from the same manufacturer, but discrete batches, can be significantly different.