Malaysian Journal of Analytical Sciences, Vol 27 No 6 (2023): 1205 - 1215

 

EVALUATING THE POTENTIAL OF CHEMOMETRICS TECHNIQUES AS RAPID SCREENING TOOLS FOR BLACK GEL INKS DISCRIMINATION

 

(Menilai Potensi Teknik Kemometrik sebagai Alat Saringan Pantas untuk Diskriminasi Dakwat Hitam Gel)

 

Nur Atiqah Zaharullil1,2, Dzulkiflee Ismail1*, Wan Nur Syuhaila Mat Desa1, and Nik Fakhuruddin Nik Hassan1

 

1Forensic Science Programme, School of Health Sciences
Universiti Sains Malysia, Health Campus, 16150 Kubang Kerian, Kelantan, Malaysia

2Universiti Teknologi MARA Jasin Campus 77300 Melaka

 

*Corresponding author: dzulkiflee@usm.my

 

 

Received: 20 July 2023; Accepted: 15 October 2023; Published:  29 December 2023

 

 

Abstract

Examining the questioned documents can offer essential scientific proof that the documents are authentic. Examining inks and handwriting to establish authenticity, authorship, suspected counterfeiting, and/or modifications are forensic problems that require critical attention. Due to gel pens popularity and widespread usage, their emergence in criminal cases associated with questioned documents are therefore anticipated. A dissolution test by dissolving gel ink into organic solvent can sometimes be used for rapid discrimination of gel ink into either pigment-based or dye-based colourants. However, due to its extremely destructive nature, this test is unfavourable for forensic document examination purposes. The main aim of this study was to develop a model that could be used to determine the nature of colourant in black gel ink without having to perform the destructive dissolution test. To achieve this, black gel pen inks of different brands/models (n = 30) that were procured from 23 different manufacturers from Malaysia, India, and China were initially dissolved in a series of organic solvents, and the nature of their colourants was recorded. Thereafter, their infrared (IR) spectra profiles were acquired using the attenuated total reflectance - Fourier transform infrared (ATR-FTIR) spectroscopy, and then preprocessed prior to feature selection using the principal component analysis (PCA). The selected features were used for the development of a classifier using the linear discriminant analysis (LDA), whereby 98.1% of correct classification was recorded for the cross-validated samples. Furthermore, it signified the potential of this approach for rapid screening of black gel ink without having to perform the destructive dissolution test, which could be utilised by forensic document examiners.

 

Keywords: black gel inks, forensic science, questioned document, attenuated total reflectance infrared spectroscopy, principal component analysis

 

Abstrak

Meneliti dokumen yang dipertikai boleh memberikan bukti saintifik penting bahawa dokumen itu sahih. Memeriksa dakwat dan tulisan tangan untuk menentukan keaslian, kepengarangan, disyaki pemalsuan dan/atau pengubahsuaian adalah masalah forensik yang memerlukan perhatian kritikal. Disebabkan oleh populariti pen dakwat gel dan penggunaannya yang semakin meluas, kemunculan mereka dalam kes jenayah yang berkaitan dengan dokumen yang dipertikai adalah dijangkakan. Ujian pembubaran dengan melarutkan dakwat gel ke dalam pelarut organik kadangkala boleh digunakan untuk diskriminasi pantas dakwat gel kepada sama ada berasaskan pigmen atau pewarna. Walau bagaimanapun, disebabkan sifatnya yang sangat merosakkan, ujian ini tidak sesuai untuk tujuan pemeriksaan dokumen forensik. Matlamat utama kajian ini adalah untuk membangunkan model yang boleh digunakan untuk menentukan sifat pewarna dalam dakwat gel hitam tanpa perlu melakukan ujian pelarutan yang merosakkan. Untuk mencapai matlamat ini, dakwat pen gel hitam daripada jenama/model berbeza (n = 30) yang diperoleh daripada 23 pengeluar berbeza dari Malaysia, India, dan China, pada mulanya dilarutkan dalam satu siri pelarut organik, dan sifat pewarnanya direkodkan. Berikutan itu, profil spektrum inframerah (IR) mereka diperoleh menggunakan spektroskopi jumlah pemantulan yang dilemahkan - inframerah transformasi Fourier (ATR-FTIR), dan kemudian pra-diproses sebelum pemilihan ciri menggunakan analisis komponen utama (PCA). Ciri-ciri yang dipilih telah digunakan untuk pembangunan pengelas menggunakan analisis diskriminasi linear (LDA), di mana 98.1% pengelasan yang betul telah direkodkan untuk sampel-sampel yang disahkan  silang, yang menandakan potensi pendekatan ini untuk pemeriksaan pantas dakwat gel hitam tanpa perlu melakukan ujian pelarutan yang merosakkan, yang boleh digunakan oleh pemeriksa dokumen forensik.

 

Kata kunci: dakwat gel hitam, sains forensik, dokumen yang dipersoalkan, spektroskopi inframerah jumlah pemantulan yang dilemahkan, analisis komponen utama

 

References

1.       Ortiz-Herrero, L., de Almeida Assis, A. C., Bartolomé, L., Alonso, M. L., Maguregui, M. I., Alonso, R. M., and Seixas de Melo, J. S. (2020). A novel, non-invasive, multi-purpose and comprehensive method to date inks in real handwritten documents based on the monitoring of the dye ageing processes. Chemometrics and Intelligent Laboratory Systems, 207: 1-11.

2.       Said, H. M., and Ismail, D. (2018). Study on the effect of ageing to gel pen ink on papers using attenuated reflectant mode fourier transform infrared (ATR-FTIR) spectroscopy. The International Journal of Medicine and Sciences, 3(1): 38-43.

3.       Hoang, A. D., Tu, M. B., Ta, T. T. and Hoang, M. H. (2021). Combination of a green and a traditional method for estimating relative and absolute ink age: A case study of ballpoint pen ink dating in Vietnam. Journal of Analytical Methods in Chemistry, 3: 1-10.

4.       Gautam, R., Chauhan, R., Kumar, R. and Sharma, V. (2021). PLS-DA and infrared spectroscopy based rapid and non-destructive discrimination of black ball and gel pen inks for forensic application. Forensic Science International: Reports, 3: 1-8.

5.       Kumar, R. and Sharma, V. (2017). A novel combined approach of diffuse reflectance UV–Vis-NIR spectroscopy and multivariate analysis for non-destructive examination of blue ballpoint pen inks in forensic application. Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy, 175: 67-75.

6.       Qureshi, R., Wasim, M. and Ashraf, M. (2022). Forensic discrimination of blue ballpoint, gel and oil-gel pens: Application of chemometrics to ATR-FTIR Data. International Journal of Forensic Sciences, 7(3): 1-12.

7.       Florence, D. C., Harralson, H. H. and Gbarabe, J. (2018). An introduction to gel inks: History and analysis. Journal of Forensic Document Examination, 28: 105-124.

8.       Calcerrada, M. and García-Ruiz, C. (2015). Analysis of questioned documents: A review. Analytica Chimica Acta, 853(1): 143-166.

9.       Narayan, V., Shalini, S. and Agrawal, N. (2015). Forensic identification and differentiation of different indian brands of gel pen inks. International Journal for Scientific Research & Development, 3(1): 557-561.

10.    Łydżba-Kopczyńska, B., Czaja, T., Cieśla, R. and Rusek, G. (2021). Application of chemometric methods for the determination of fading and age determination of blue ballpoint inks. Journal of Raman Spectroscopy, 52(1): 159-169.

11.    Durney, L. (2015). Using vibrational spectroscopy to analyse the effect of environmental aging on gel pen inks.Thesis of Master Degree, University of Central Lancashire.

12.    Nastova, I., Grupče, O., Minčeva-Šukarova, B., Ozcatal, M. and Mojsoska, L. (2013). Spectroscopic analysis of pigments and inks in manuscripts: I. Byzantine and post-Byzantine manuscripts (10-18th century). Vibrational Spectroscopy, 68: 11-19.

13.    Sharma, V. and Kumar, R. (2017). Dating of ballpoint pen writing inks via spectroscopic and multiplelinear regression analysis: A novel approach. Microchemical Journal, 134: 104-113.

14.    Silva, C. S., Borba, F. de S. L., Pimentel, M. F., Pontes, M. J. C., Honorato, R. S. and Pasquini, C. (2013). Classification of blue pen ink using infrared spectroscopy and linear discriminant analysis. Microchemical Journal, 109: 122-127.

15.    Yadav, P. K. and Sharma, R. M. (2020). Classification of fiber tip pens using attenuated total reflectance (ATR) – Fourier transform infrared (FTIR) spectroscopy in tandem with chemometrics. Vibrational Spectroscopy, 108: 1-17.

16.    Mohamad Asri, M. N., Verma, R., Mahat, N. A., Mohd Nor, N. A., Mat Desa, W. N. S. and Ismail, D. (2022). Raman spectroscopy with self-organizing feature maps and partial least squares discriminant analysis for discrimination and source correspondence of red gel ink pens. Microchemical Journal, 175: 1-10.

17.    Chaplin, T. and Clark, R. (2016). Raman microscopy techniques for the characterisation of pigments. Royal Microscopical Society, 3(3): 86-98.

18.    Kunicki, M., Fabiańska, E. and Parczewski, A. (2013). Raman spectroscopy supported by optical methods of examination for the purpose of differentiating blue gel pen inks. Problems of Forensic Sciences, 95: 627-641.

19.    Geiman, I., Leona, M. and Lombardi, J. R. (2009). Application of raman spectroscopy and surface-enhanced raman scattering to the analysis of synthetic dyes found in ballpoint pen inks. Journal of Forensic Sciences, 54 (4): 947-952.

20.    Mazzella, W. D. and Buzzini, P. (2005). Raman spectroscopy of blue gel pen inks. Forensic Science International, 152 (2-3): 241-247.

21.    Senior, S., Hamed, E., Masoud, M. and Shehata, E. (2012). Characterization and dating of blue ballpoint pen inks using principal component analysis of UV-Vis absorption spectra, ir spectroscopy, and HPTLC. Journal of Forensic Sciences, 57 (4): 1087-1093.

22.    Thanasoulias, N. C., Parisis, N. A. and Evmiridis, N. P. (2003). Multivariate chemometrics for the forensic discrimination of blue ball-point peninks based on their Vis spectra. Forensic Science International, 138(1-3):75-84.

23.    Gorziza, R., González, M., de Carvalho, C., Ortiz, R., Ferrão, M. and Limberger, R. (2022). Chemometric approaches in questioned documents. Brazilian Journal of Analytical Chemistry, 34: 35-51.

24.    Gemperline, P. (2006). Practicle guide to chemometric. Taylor & Francis, New York: pp.1-7.

25.    Axelson, D. E. (2010). Data preprocessing for chemometric and metabonomic analysis. First Choice Books:pp. 330-336.

26.    Sauzier, G. Y. (2016). Applications of chemometrics to the analysis and interpretation of forensic physical evidence. Thesis of Doctor of Philosophy, Curtin University.

27.    Reed, G. (2013). Multivariate profiling of gel inks. Thesis of Doctor of Philosophy, University of Strathclyde, United Kingdom.

28.    Mohamad Asri, M. N. and Ismail, D. (2018). Combined principal component analysis (PCA) and hierarchical cluster analysis (HCA): An efficient chemometric approach in aged gel inks discrimination. Australian Journal of Forensic Sciences, 52(1): 38-59.

29.    Gawad, A. A., Salama, T. M., Meshref, M., Mohamed, G. G. and Zedan, A. F. (2022). Coupling ATR-FTIR spectroscopy and chemometric analysis for rapid and non-destructive ink discrimination of forensic documents. Egyptian Journal of Chemistry, 65(8): 167-179.

30.    Kher, A., Mulholland, M., Green, E. and Reedy, B. (2006). Forensic classification of ballpoint pen inks using high performance liquid chromatography and infrared spectroscopy with principal components analysis and linear discriminant analysis. Vibrational Spectroscopy, 40(2): 270-277.