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Fiber traces are one of (micro)traces that can be found at a crime scene. They are easily transferable and, like other forms of evidence, can provide a link between a suspect and a victim. The main purpose of this review is to present methods developed to examine textile dyes extracted for forensic purposes using different capillary electromigration methods (CEMs). Scientific papers, mainly from the 20th century, provide reliable methods for the separation of water-soluble dyes. However, dyes insoluble in aqueous solutions have been and still are a challenge. Another problem is the sensitivity of the developed methods, which is, in most cases, insufficient for forensic examination of dyes extracted from a single fiber preserved at the crime scene. Although the methodologies already developed and presented in this review have the potential to be applied in a comparative analysis of textile dye traces, there seems to be a lot of work to be conducted. Some ideas on how to resolve these problems are presented and discussed in the article. [ABSTRACT FROM AUTHOR]

Cosmetics are becoming more and more popular; consequently, the chance of finding them as microtraces at a crime scene increases. They are easily transferable and can provide a link between a suspect and a victim. For this reason, identifying and comparative analysis of red lipstick – the most popular and used – is required. The aim of this study was to apply a multitechnique methodology for the comparative forensic analysis of the red lipsticks traces of a very similar hue. For this purpose, four methods of different physicochemical basics – two nondestructive spectroscopic and two destructive separation techniques – were used. The possibilities and advantages of attenuated total reflection infrared spectroscopy (ATR‐FTIR), confocal Raman microscopy (CRM), capillary electrophoresis (MEKC) and gas chromatography‐mass spectrometry (GC‐MS) have been combined. Specially prepared lipstick traces in various forms (imprints, smears) on different surfaces (absorbent and nonabsorbent) were analyzed to confirm the usefulness of the proposed methods. The premise is that if two methods yield a consistent result, the investigation is terminated at this stage. All investigated traces were properly identified. First, the ATR‐FTIR method as a nondestructive technique is recommended. Sometimes, due to strong interferences from the substrates, the newly proposed method with the use of confocal Raman microscopy may be an alternative. The next recommendation is the MEKC method. Only in case of the absence of unambiguous conclusions, it is proposed to use the GC‐MS method. This methodology has the potential to be applied in the comparative analysis of red lipsticks for forensic purposes. [ABSTRACT FROM AUTHOR]

The study focused on comparison of on-line sample concentration techniques, i.e. sample stacking modes, applied in capillary electrophoresis in order to improve the detection of components of stamp pad inks so that destruction of analysed document could be minimized. In particular, such techniques were taken into consideration as: normal stacking mode/field amplified sample stacking (NSM/FASS), high-salt concentration, sweeping, electrokinetic injection + FASS, and field enhanced sample injection (FESI). At first, two mixtures of 4 red dyes and 4 violet/blue dyes were examined. As a result, in case of red dyes two environments: ACN/1 mg mL −1 aqueous NaCl (95:5, v/v) and 10-fold water dilution of BGE preceded by water plug (6 s, 0.7 psi) injection, were chosen as the most promising for further examination. Regarding the blue/violet dyes, the 100-fold water dilution of BGE was selected as giving the best increase of height of peaks. Ultimately, nine stamp pad inks in three colours (red, blue and violet) produced by different manufacturers were examined under the optimal conditions. Only 5 dots cut-out from inked paper were sampled. Almost all examined samples were possible to be differentiated basing on the obtained electrophoretic profiles. In conclusion, the developed sample stacking mode of MECC–based method was found as a useful tool in the differentiation of stamp pad inks for the purposes of forensic questioned document analysis. [ABSTRACT FROM AUTHOR]

The potential of capillary electrophoresis coupled to mass spectrometry with electrospray ion source and time of flight analyser (CE-ESI-TOF-MS) in the analysis of inkjet inks was investigated. The developed and validated method allowed reliable and repeatable analysis of black inkjet inks extracted from printouts. Over a dozen inkjet printouts printed on various printer models from different manufacturers were analysed under selected conditions to determine the variation of chemical composition of inks between different brands and types. It was ascertained that the developed method is capable of revealing qualitative differences between ink samples. For most of the investigated inks, the studies showed the presence of a characteristic mass spectrum originating from the surfactant or polymer. The mass distribution of the additive is distinctive for some inkjet ink producers, and allows for group identification of inks. The results showed the strength of the CE-ESI-TOF-MS method as an effective technique for forensic purposes, requiring a small amount of inkjet ink samples and giving analytical information that is useful in the identification of compounds. [ABSTRACT FROM AUTHOR]

Forensic laboratories are increasingly engaged in the examination of fraudulent documents, and what is important, in many cases these are inkjet-printed documents. That is why systematic approaches to inkjet printer inks comparison and identification have been carried out by both non-destructive and destructive methods. In this study, micro-Raman spectroscopy and capillary electrophoresis (CE) were applied to the analysis of colour inkjet printer inks. Micro-Raman spectroscopy was used to study the chemical composition of colour inks in situ on a paper surface. It helps to characterize and differentiate inkjet inks, and can be used to create a spectra database of inks taken from different cartridge brands and cartridge numbers. Capillary electrophoresis in micellar electrophoretic capillary chromatography mode was applied to separate colour and colourless components of inks, enabling group identification of those components which occur in a sufficient concentration (giving intensive peaks). Finally, on the basis of the obtained results, differentiation of the analysed inks was performed. Twenty-three samples of inkjet printer inks were examined and the discriminating power (DP) values for both presented methods were established in the routine work of experts during the result interpretation step. DP was found to be 94.0% (Raman) and 95.6% (CE) when all the analysed ink samples were taken into account, and it was 96.7% (Raman) and 98.4% (CE), when only cartridges with different index numbers were considered. [ABSTRACT FROM AUTHOR]

Questioned document examination in a wide variety of criminal and civil cases often focuses on the identification and comparison of stamp inks. Increasingly frequent counterfeiting of documents, especially those that have been stamped, has led to a growing need for instrumental methods that will allow an in-depth examination of stamp inks on a document. Therefore, the usefulness of two capillary electrophoresis techniques: micellar electrophoretic capillary chromatography with UV/Vis diode array detection (MECC-DAD) and capillary zone electrophoresis with electrospray mass spectrometric detection (CZE-ESI/MS) was verified for this purpose. Violet, red, blue and green stamp inks on paper surfaces were investigated. Electropherograms and mass spectra of inks purchased from 10 different producers were obtained in accordance with optimized and validated analytical procedures. It was shown that effective differentiation of individual inks was possible in terms of migration time and UV/ Vis spectra provided that there was more than one characteristic peak. However, the most problematic inks with only one very similar (or identical) dye component - violet and blue ones - were additionally differentiated by CZE-MS. The obtained results showed that the proposed procedures can be useful for the objective analysis of questioned documents involving stamp inks. Consequently, the developed methods can be applied in the forensic field, including in the investigation of the authenticity of documents. [ABSTRACT FROM AUTHOR]

Abstract: Counterfeiting of documents is a common phenomenon in the modern world. A large proportion of forgeries relates to inkjet printed documents. Hence there is an evident need to develop an effective and reliable method for the differentiation and identification of inkjet inks on questioned documents. The aim of the presented study was to investigate the possibility of applying micellar electrokinetic capillary chromatography (MECC) to forensic analysis of inkjet inks extracted from black and white printouts. In order to achieve the above aim, a capillary electrophoresis system equipped with a diode array detector was used. The separation was performed using a fused silica capillary (60/50cm total/effective length, 75μm i.d.) with a background electrolyte composed of 40mM sodium borate, 20mM SDS and 10% (v/v) acetonitrile (pH 9.5) at 25°C and 30kV. Ink samples were extracted from black inkjet printouts with the use of dimethyl sulphoxide (DMSO). Differentiation of inks was based on the number of significant peaks at different wavelengths, the relative migration times and the characteristic UV–Vis spectra. The electropherograms of the inks extracted from paper showed patterns which in most cases were distinctly different from each other. The greatest diversity of electrophoretic profiles was revealed for documents printed by Hewlett-Packard inkjet technology. A database of electrophoretic separation results of inks has been constructed for further forensic use. [Copyright &y& Elsevier]