Multivariate chemometric discrimination of black ballpoint pen inks based on infrared spectra

A method for differentiating two brands of black ballpoint pen inks was developed based on infrared spectra (IR) and chemometric methods including discriminant analysis (DA), hierarchical agglomerative cluster analysis (HACA) and principal component analysis (PCA). The spectral region 4000-400 cm^-1 was used to `fingerprint´ ink comprising a total of 33 samples. Analysis of the spectra of different types of each brand of ink showed clear discrimination of the two brands of inks with 100% correctly assigned discriminant analysis. PCA analysis of these spectra resulted in four latent factors explaining 84.22% of the total variance. This study showed that infrared spectra in combination with chemometric analysis were able to classify these inks in an objective manner.