Raman imaging for determining the sequence of blue pen ink crossings

Braz, André; Lopez‐López, María; García-Ruiz, Carmen

doi:10.1016/j.forsciint.2015.01.023

Cited by 39 publications

(18 citation statements)

References 20 publications

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“…This technique is a nondestructive analysis, it needs no sample preparation, and the sample size can be in the order of picograms. Recently, Raman spectroscopy has been shown to be an effective multipurpose analytical method for forensic applications: identification of drugs [3], lipsticks [4], fibers [5], paints [6], and ink [7]. A previous study reported the identification of body fluids using Raman spectroscopy [8].…”

Section: Introductionmentioning

confidence: 99%

Blood identification and discrimination between human and nonhuman blood using portable Raman spectroscopy

et al. 2016

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Raman spectroscopy is commonly used in chemistry to identify molecular structure. This technique is a nondestructive analysis and needs no sample preparation. Recently, Raman spectroscopy has been shown to be effective as a multipurpose analytical method for forensic applications. In the present study, blood identification and discrimination between human and nonhuman blood were performed by a portable Raman spectrometer, which can be used at a crime scene. To identify the blood and to discriminate between human and nonhuman blood, Raman spectra of bloodstains from 11 species (human, rat, mouse, cow, horse, sheep, pig, rabbit, cat, dog, and chicken) were taken using a portable Raman spectrometer. Raman peaks for blood (742, 1001, 1123, 1247, 1341, 1368, 1446, 1576, and 1619 cm) could be observed by the portable Raman spectrometer in all 11 species, and the human bloodstain could be distinguished from the nonhuman ones by using a principal component analysis. This analysis can be performed on a bloodstain sample of at least 3 months old. The portable Raman spectrometer can be used at a crime scene, and this analysis is useful for forensic examination.

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Section: Introductionmentioning

confidence: 99%

Blood identification and discrimination between human and nonhuman blood using portable Raman spectroscopy

et al. 2016

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“…Braz et al 124,125 published two studies on the matter. In the first, 124 they investigated the Raman spectral variability of 190 blue pens of different ink types, brands, models and batches.…”

Section: Raman Spectroscopy In Document Analysismentioning

confidence: 99%

Vibrational Spectroscopy and Chemometrics in Forensic Chemistry: Critical Review, Current Trends and Challenges

Silva¹,

Braz²,

Pimentel³

2019

J. Braz. Chem. Soc.

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The present manuscript makes an extensive review of the scientific approaches developed in the last decade involving infrared and Raman spectroscopy combined with chemometrics for solving several issues in the investigation of the most relevant forensic traces, such as questioned documents and currency, explosives, gunshot residues, illicit drugs and body fluids. In addition, current trends, main challenges and the adequate use of several chemometric techniques are discussed. Principal component analysis (PCA) was found to be the most used technique. This unsupervised approach, however, has sometimes been misunderstood as a classification technique. Discriminant analysis techniques are widely employed, leaving a range of possibilities for application of class-modeling techniques, particularly in cases of problems regarding only one target class. In addition, increasingly complex dataset structures frequently require nonlinear approaches or flexible techniques such as multivariate curve resolution-alternating least squares (MCR-ALS). Results reporting, however, still lack reliable quality parameters and sample representativeness, posing a significant challenge to the solution of forensic problems. Regarding the analytical techniques, Raman has been playing an important role, especially in the area of questioned documents and of body fluids. Portable and hyperspectral imaging infrared spectrometers have also been showing significant potential in forensic applications.

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“…In principle, if a document is altered so that a new ink line is drawn over an existing one the ink molecules of the later will lie on top of the original, so that methods which are depth sensitive should be able to determine the order of the lines. Although various methods based on advanced instrumentations from focused ion beam microscopy to spectrophotometry have been proposed, all have shown limited success [34,35]. As shown in Figure 5 normal Raman measurements of the test sample with crossing blue and green ink lines do not give sufficient discrimination but the SENSERS spectra at the crossing points are indeed dominated by the ink in the uppermost line.…”

Section: Sensers For Trace Analysis Of Real-life Samplesmentioning

confidence: 99%

Pressing solids directly into sheets of plasmonic nanojunctions enables solvent-free surface-enhanced Raman spectroscopy

et al. 2018

Applied Materials Today

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Often chemical analysis of solid materials begins with dissolving the sample in a solvent but this is undesirable, particularly if the physical form is important. In principle surfaceenhanced Raman spectroscopy (SERS) should allow detection of solid analytes and offers attomolar sensitivity combined with molecular specificity. SERS requires the target molecules to sit in plasmonic hot-spots, which are normally nanojunctions, just a few nm across. This means that solid samples normally need to be dissolved in a solvent so they can diffuse into the enhancing region. Here, we show that SERS spectra of picograms of solid analytes can be directly obtained by pressing them into a flexible SERS substrate with a dense field of exposed nanojunction hot-spots anchored on its surface. We demonstrate that this can be a powerful tool for straightforward and non-destructive forensic analysis of layered materials (crossing ink lines), solid explosives and illicit drugs as well as for studying previously intractable samples such as pharmaceutical co-crystals, whose important solid state structure is lost when they are dissolved.

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Raman imaging for determining the sequence of blue pen ink crossings

Cited by 39 publications

References 20 publications

Blood identification and discrimination between human and nonhuman blood using portable Raman spectroscopy

Blood identification and discrimination between human and nonhuman blood using portable Raman spectroscopy

Vibrational Spectroscopy and Chemometrics in Forensic Chemistry: Critical Review, Current Trends and Challenges

Pressing solids directly into sheets of plasmonic nanojunctions enables solvent-free surface-enhanced Raman spectroscopy

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