Multivariate chemometric discrimination of blue gel-pen inks by fourier transform infrared spectroscopy: Diskriminasi kimometrik statistik terhadap pen gel dakwat biru dengan spektroskopi sinar merah

The aim of this study is to discriminate and classify fifteen blue gel-pen inks from five different brands (Pilot, Faster, M&G, G-Soft and Faber Castell) available in Malaysia market. Discrimination method was developed based on the combination of infrared (IR) spectroscopy with chemometric technique which comprise of principal component analysis (PCA) and Agglomerative Hierarchical Clustering (AHC). The XLSTAT 2012 was used as software to analyze IR spectra. The spectral region (wavenumber) 4000-400 cm^-1 was used to `fingerprint´ each ink from the fifteen samples. PCA used to detect any outliers while AHC used to separate inks into their own class. PCA showed 74.67% of the acceptable statistical discrimination value between these fifteen blue gel-pen inks. FTIR-PCA and FTIR-AHC were successfully discriminate Pilot and Faber Castell. Faster, M&G and G-Soft not discriminated perfectly but these brands still provide a reasonable discrimination. The result of this study indicate that Transmission FTIR spectroscopy coupled with chemometric can be more powerful discriminating tool for forensic investigator to investigate the cases involving inks.