Bahman, Nur Atiqah Salwa
(2015)
“Characterization of Blue Ballpoint Pens
Using UV-Visible Spectroscopy and Pattern Recognition
Techniques”.
Project Report.
Universiti Sains Malaysia.
(Submitted)
Abstract
Analysis of ink is important particularly in the investigation of forgery cases involving
handwriting and signatures. Characterisation of ballpoint pen inks among different
brands becomes of great interest in questioned document since most of documents
are written using ballpoint pens. The purpose of this study was to evaluate the
possibility of discriminating 24 blue ballpoint pen inks from four different brands
namely Kilometrico, G’Soft, Faber Castell and Stabilo.
The blue ballpoint pen inks components were first separated using Thin Layer
Chromatography (TLC) before the ink extracts were subjected to UltraViolet-Visible
(UV-Vis) spectroscopy. The colour of the spots developed on the TLC plate and their
Rf values as well as the UV-Vis spectra were examined manually by direct visual
examination in attempt to classify the ink into their respective group. However, this
approach had failed to differentiate the ink. The UV-Vis spectra of the ink which could
not be differentiated were introduced to chemometrics techniques of Principal
Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA). PCA had
successfully differentiated and grouped all the blue ballpoint pen inks according to
their brands manifested in the score plot. Using the Euclidean distance as the
proximity measure and complete linkage as the linkage strategy to link cluster, HCA
had also successfully differentiate the blue ballpoint pen inks under study according
to the brand. The results proved that the UV-Vis spectra combine with chemometrics
technique of PCA and HCA can be effective tool to differentiate blue ballpoint pen
inks of different brands
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