Forensic classification of ballpoint pen inks using high performance liquid chromatography and infrared spectroscopy with principal components analysis and linear discriminant analysis

Kher, Ashwini; Mulholland, M.; Green, Elinore; Reedy, Brian

doi:10.1016/j.vibspec.2005.11.002

Cited by 103 publications

(61 citation statements)

References 24 publications

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“…12 All of these articles also described the difficulties caused by the complexity of the chemical matrix due to the presence of a wide range of contaminants/adulterants, which demands the use of multivariate chemometric methods. In particular, the combined use of FTIR and principal component analysis (PCA) has proved to be a rapid and non-destructive analysis tool of great importance in criminal investigations, and has been recently used in other subjects of forensic interest, such as the discrimination of ballpoint pen inks 13 and spray paints. 14 The aim of this article was to chemically characterize cocaine samples seized between 2008 and 2010 by the Federal Police of the Minas Gerais State (Brazil), which is the government organization responsible for international and interstate drug traffic control.…”

Section: Introductionmentioning

confidence: 99%

Analysis of seized cocaine samples by using chemometric methods and FTIR spectroscopy

Rodrigues¹,

Cardoso²,

Andrade³

et al. 2013

J. Braz. Chem. Soc.

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O objetivo deste trabalho foi desenvolver uma metodologia quimiométrica para descrever o perfil químico de amostras de cocaína apreendidas no estado de Minas Gerais (Brasil). A identificação de adulterantes e a quantificação do teor de cocaína foram feitas por cromatografia gasosa acoplada à espectrometria de massa (GC-MS). Espectros de 91 amostras foram obtidos por espectroscopia no infravermelho usando refletância total atenuada (ATR-FTIR), e utilizados na construção de um modelo de análise de componentes principais (PCA). A primeira componente principal (PC1) discriminou as amostras de maior pureza das mais diluídas/adulteradas, nas quais foram identificadas lidocaína, cafeína e benzocaína. PC2 discriminou a forma química da cocaína, cloridrato ou base. Além disso, dois modelos supervisionados discriminantes (mínimos quadrados parciais para análise discriminante, PLS-DA) foram desenvolvidos para classificar as amostras em função de sua diluição (abaixo e acima de 15% m/m) e de sua forma química, apresentando taxas de acerto que variaram entre 83 e 97%. Os modelos de classificação constituem uma ferramenta simples, rápida e não destrutiva, de grande valor para peritos forenses e investigadores criminais.The aim of this article was to develop a chemometric methodology for determining the chemical profile of cocaine samples seized in Minas Gerais State, Brazil. The adulterant detection and the cocaine determination were performed by gas chromatography-mass spectrometry (GC-MS). Spectra of 91 samples were obtained by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and used to build an exploratory principal component analysis (PCA) model. The first principal component (PC1) discriminated samples of more purity from the more diluted/adulterated ones, which were characterized by the presence of lidocaine, caffeine and benzocaine. PC2 discriminated the two chemical forms of cocaine, hydrochloride and base. In addition, two supervised discriminant partial least-squares models (partial least-squares discriminant analysis, PLS-DA) were developed for classifying the samples according to dilution (above and below 15% m/m) and chemical form, with a rate of success that varied between 83 and 97%. The classification models constitute a simple, rapid and non-destructive tool, of great value for both forensic experts and criminal investigators. Keywords: illicit drugs, MID infrared, principal component analysis, cocaine, chemometrics IntroductionCocaine is an alkaloid extracted from plants of the genera Erythroxylum (E. novagranatense and E. coca). United Nations Office on Drugs and Crime (UNODC) considers cocaine, after heroin, the second most problematic drug worldwide in terms of negative health consequences and probably the most problematic drug in terms of trafficking-related violence. Estimates suggest that 440 t of pure cocaine were consumed in the world in 2009, which would be in line with a total production estimate of 1,111 t, wholesale purity-adjusted seizures Analysis of Seized Cocain...

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Section: Introductionmentioning

confidence: 99%

Analysis of seized cocaine samples by using chemometric methods and FTIR spectroscopy

Rodrigues¹,

Cardoso²,

Andrade³

et al. 2013

J. Braz. Chem. Soc.

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show abstract

“…However, such methods are invasive and time-consuming [6], and these disadvantages must be considered. Different approaches, such as Raman spectroscopy [7][8][9][10], UV-Vis spectroscopy [4,11], and IR spectroscopy [12], are based on the interaction of light with the substrate. Those methods ensure the physical integrity of the document, and yield data on organic and inorganic components of a sample.…”

Section: Introductionmentioning

confidence: 99%

Hyperspectral imaging coupled with chemometric analysis for non-invasive differentiation of black pens

et al. 2016

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Differentiation of the written text can be performed with a non-invasive and non-contact tool that connects conventional imaging methods with spectroscopy. Hyperspectral imaging (HSI) is a relatively new and rapid analytical technique that can be applied in forensic science disciplines. It allows an image of the sample to be acquired, with full spectral information within every pixel. For this paper, HSI and three statistical methods (hierarchical cluster analysis, principal component analysis, and spectral angle mapper) were used to distinguish between traces of modern black gel pen inks. Non-invasiveness and high efficiency are among the unquestionable advantages of ink differentiation using HSI. It is also less time-consuming than traditional methods such as chromatography. In this study, a set of 45 modern gel pen ink marks deposited on a paper sheet were registered. The spectral characteristics embodied in every pixel were extracted from an image and analysed using statistical methods, externally and directly on the hypercube. As a result, different black gel inks deposited on paper can be distinguished and classified into several groups, in a non-invasive manner.

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“…Details of relevant algorithms for both iPCA and siPCA can be found in [4]. In the field of forensic science, PCA is a popular exploratory and dimensionality reduction technique [6][7][8][9]. However, there is a lack of literature on the application of the aforementioned variants of PCA in forensic analysis.…”

Section: Introductionmentioning

confidence: 99%

Comparison of several variants of principal component analysis (PCA) on forensic analysis of paper based on IR spectrum

Lee¹,

Liong²,

Osman³

et al. 2016

AIP Conference Proceedings

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Forensic classification of ballpoint pen inks using high performance liquid chromatography and infrared spectroscopy with principal components analysis and linear discriminant analysis

Cited by 103 publications

References 24 publications

Analysis of seized cocaine samples by using chemometric methods and FTIR spectroscopy

Analysis of seized cocaine samples by using chemometric methods and FTIR spectroscopy

Hyperspectral imaging coupled with chemometric analysis for non-invasive differentiation of black pens

Comparison of several variants of principal component analysis (PCA) on forensic analysis of paper based on IR spectrum

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