Exploring volatile organic profiles of red pen inks based on gas-chromatography-flame ionization detection (GC-FID) and chemometric methods for forensic investigation purposes

Abstract

Criminal cases involving questioned documents often cause the loss of a huge amount of money in a country. Red ballpoint pen inks found on threatening notes, or any official documents are potentially encountered by a forensic document examiner as questioned documents. Identifying sources of the questioned ink entries is paramount to revealing the authenticity or sources of the document. Despite the multitude of works being devoted to discriminating pen inks by their sources, very little is focused on the volatile fractions. In this study, the volatile compositional profiles of ten types of red ballpoint pen inks as acquired by gas chromatography-flame ionization detection (GC-FID) were studied using various multivariate exploratory tools. Scores plot of principal component analysis reveals that inter-pen brand variation is higher than the inter-pen type variation. Meanwhile, hierarchical clustering analysis showed that 6 of the 10 pen types and all five pen brands could be discriminated. In conclusion, volatile organic compositions of red pen inks are useful in classifying the pen inks by brands. The outcome of the study will provide vital insight into the potential of volatile organic profiles in discriminating red pen inks sold in Malaysia.