The Malaysian Journal of Analytical Sciences Vol 16 No 3 (2013): 262 – 272

 

 

 

SYSTEMATIC ASSESSMENT OF ATTENUATED TOTAL REFLECTANCE-FOURIER TRANSFORMS INFRARED SPECTROSCOPY COUPLED WITH MULTIVARIATE ANALYSIS FOR FORENSIC ANALYSIS OF BLACK BALLPOINT PEN INKS

 

(Penilaian Bersistem Spektroskopi Mikro-ATR-FTIR yang Digabungkan dengan Analisis Multivariat untuk Analisis Forensik Pen Mata Bulat  Dakwat Hitam)

 

L. C. Lee ^1,2, Mohamed Rozali Othman¹*, and H. Pua²

 

¹School of Chemistry Sciences and Food Technology,

Faculty of Science & Technology,

Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor D.E. Malaysia;

 ² Program of Forensic Science, Faculty of Health Science,

Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur, Malaysia

 

*Corresponding author: rozali@ukm.my

 

 

Abstract

This manuscript aims to provide a new and non-destructive method for systematic analysis of inks on a questioned document. Ink samples were analyzed in situ on the paper substrate by micro-ATR-FTIR spectroscopy and the data obtained was processed and evaluated by a series of multivariate chemometrics. Absorbance value from wavenumbers of 2000-675 cm^-1 were first processed by cluster analysis (CA), followed by principal component analysis (PCA) to form a set of new variables. Subsequently, the variables set was used for classification, differentiation and identification of 155 sample pens that comprise nine different brands. Results show that nine black ballpoint pen brands could be classified into three main groups via discriminant analysis (DA). Differentiation analyses of nine different pen brands performed using one-way ANOVA indicated only two pairs of brands cannot be differentiated at 95% confidence interval. Finally an identification flow chart was proposed to determine the brand of unknown pen inks. As a conclusion, the proposed method for extracting and creating a new variable set from infrared spectrum was evaluated to be satisfactory for systematic analysis of inks based on their infrared spectrum.

 

Keywords: Forensic science; ATR-FTIR spectroscopy; classification; differentiation; ink analysis; multivariate analysis

 

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