A new approach to forensic analysis with infrared microscopy: Internal reflection spectroscopy

Bartick, Edward G.; Tungol, Mary W.; Reffner, John A.

doi:10.1016/0003-2670(94)85114-x

Cited by 54 publications

(19 citation statements)

References 11 publications

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“…The entire set of 807 samples was not available at the time of this study. Toners were transferred from documents to reflective media (heavy duty aluminum foil affixed to standard glass slides with double-sided tape) using a temperature-regulated soldering iron set at 288°C [15,22,24]. The soldering iron was equipped with a screwdriver tip that had been ground off, leaving a flattened round head with a 4.8-mm diameter.…”

Section: Methodsmentioning

confidence: 99%

Forensic discrimination of photocopy and printer toners II. Discriminant analysis applied to infrared reflection-absorption spectroscopy

Egan

Morgan

Bartick

et al. 2003

Analytical and Bioanalytical Chemistry

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Copy toner samples were analyzed using reflection-absorption infrared microscopy (R-A IR). The grouping of copy toners into distinguishable classes achieved by visual comparison and computer-assisted spectral matching was compared to that achieved by multivariate discriminant analysis. For a data set containing spectra of 430 copy toners, 90% (388/430) of the spectra were initially correctly grouped into the classifications previously established by spectral matching. Three groups of samples that did not classify well contained too few samples to allow reliable classification. Samples from two other pairs of groups were similar and often misclassified. Closer examination of spectra from these groups revealed discriminating features that could be used in separate discriminant analyses to improve classification. For one pair of groups, the classification accuracy improved to 91% (81/89) and 97% (28/29), for the two groups, respectively. The other pair of groups were completely distinguishable from one another. With these additional tests, multivariate discriminant analysis correctly classified 96% of the 430 R-A IR toner spectra into the toner groups found previously by spectral matching.

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Section: Methodsmentioning

confidence: 99%

Forensic discrimination of photocopy and printer toners II. Discriminant analysis applied to infrared reflection-absorption spectroscopy

Egan

Morgan

Bartick

et al. 2003

Analytical and Bioanalytical Chemistry

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“…4 This method is nondestructive and generally allows the analysis of specimens in situ, on evidence such as garments or documents.…”

Section: Technique Evaluationmentioning

confidence: 99%

“…However, the presence of hair spray or other coatings on hair ( Figure 5) can significantly increase the value of evidence. 4 …”

Section: Hairmentioning

confidence: 99%

Microspectrophotometry in Forensic Science

Ziȩba‐Palus¹

2000

Encyclopedia of Analytical Chemistry

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Infrared microspectrophotometry is a combination of two techniques – optical microscopy and infrared (IR) spectrometry – which supply specific information about the composition and structure of a given material. The equipment used is a Fourier transform infrared (FTIR) spectrometer connected on line with an optical microscope. The microscope allows observation of a sample in white light at relatively high magnification; this allows its morphology and microstructure to be established, and facilitates selection of the area which will subsequently be subjected to IR spectrometric analysis. The microscope also permits use of polarized light in investigations. The spectrometer enables analysis of a sample with a chosen measuring technique – transmission or reflection – with the aim of determining the chemical composition of the sample. It also supplies information about its microstructure and orientation. This method is particularly useful in the analysis of trace amounts of various substances secured as material evidence in court cases, and in analysis of the homogeneity of the sample, identification of inclusions and contaminants on the surface, and detection of structural defects. A specific advantage of this method is its ability to unambiguously photograph and record marked and measured areas of the sample and minimize the process of preparing the sample for analysis. Furthermore, IR microspectrophotometry gives the rare opportunity of studying small crystals or areas in the oriented materials by using polarized IR radiation, both by the transmission and the reflection technique. Its fundamental drawback is that the physical nature of the microsample may influence the precision of the photometric measurements and cause distortion of the spectra (artefacts) obtained. Furthermore, because only a small area is studied the heterogeneity of the sample and the amount of contaminants may significantly influence the results of spectrometric measurements. Microspectrophotometry in the ultraviolet/visible (UV/VIS) range is a combination of photometric measuring techniques and optical microscopy. It allows comparison of the color of very small samples of various materials, such as single fibers, tiny amounts of paint, traces of ink or ball‐point pen ink on a forged document in an objective way, independently of the sharpness and quality of the observers's vision. It yields immediate information about spectral differences existing between two samples of similar color, which are indistinguishable by use of the optical microscope. Additionally, using appropriate software to analyze the results of microspectrometric measurements, it enables precise measurement of a color, and – applying the theory of colors – gives a color a defined numerical value; this facilitates communication between experts working with this method. The equipment consists of an optical microscope with a spectrometer for analysis in the visible and ultraviolet range, connected to a microcomputer via an analog‐to‐digital converter.

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“…Other analysis techniques have been successfully applied to inks, including highperformance liquid chromatography (HPLC) [13][14][15], capillary zone electrophoresis [15,16], Xray fluorescence [15,[17][18][19], surface-enhanced Raman spectroscopy (SERS) [20][21][22], and FT-IR spectroscopy [7,15,18,23,24]. These generally provide more compositional information than TLC does, and some of them lend themselves to computer-searchable libraries, so a reference collection of inks need not be maintained.…”

Section: Introductionmentioning

confidence: 99%

Analysis of writing inks on paper using direct analysis in real time mass spectrometry

Jones¹,

McClelland²

2013

Forensic Science International

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Ink analysis is central to questioned document examination. We applied direct analysis in real time mass spectrometry (DART MS) to ballpoint, gel, and fluid writing ink analysis. DART MS acquires the mass spectrum of an ink while it is still on a document without altering the appearance of the document. Spectra were acquired from ink on a variety of papers, and the spectrum of the blank paper could be subtracted out to produce a cleanly isolated ink spectrum in most cases. Only certain heavy or heavily processed papers interfered. The time since an ink is written on paper has a large effect on its spectrum. DART spectra change radically during the first few months after an ink is written as the more volatile components evaporate, but the spectra stabilize after that. A library-search study involving 166 well-aged inks assessed the ability to identify inks from their DART spectra. The aggregate success rate was 92%. ABSTRACTInk analysis is central to questioned document examination. We applied direct analysis in real time mass spectrometry (DART MS) to ballpoint, gel, and fluid writing ink analysis. DART MS acquires the mass spectrum of an ink while it is still on a document without altering the appearance of the document. Spectra were acquired from ink on a variety of papers, and the spectrum of the blank paper could be subtracted out to produce a cleanly isolated ink spectrum in most cases. Only certain heavy or heavily processed papers interfered. The time since an ink is written on paper has a large effect on its spectrum. DART spectra change radically during the first few months after an ink is written as the more volatile components evaporate, but the spectra stabilize after that. A library-search study involving 166 well-aged inks assessed the ability to identify inks from their DART spectra. The aggregate success rate was 92%.

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A new approach to forensic analysis with infrared microscopy: Internal reflection spectroscopy

Cited by 54 publications

References 11 publications

Forensic discrimination of photocopy and printer toners II. Discriminant analysis applied to infrared reflection-absorption spectroscopy

Forensic discrimination of photocopy and printer toners II. Discriminant analysis applied to infrared reflection-absorption spectroscopy

Microspectrophotometry in Forensic Science

Analysis of writing inks on paper using direct analysis in real time mass spectrometry

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