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Zuba D.,Institute of Forensic Research
TrAC - Trends in Analytical Chemistry | Year: 2012

The supply of psychoactive substances has changed and users increasingly buy " legal highs" over the Internet or in specialized shops. Vast arrays of preparations are marketed as legal substitutes to controlled substances. Their analysis has revealed that the majority of active components belong to one of four chemical classes: phenethylamines, tryptamines, piperazines and cathinones, the last being novel.This article gives special attention to cathinone derivatives and certain characteristic fragmentations based on the GC-EI/MS and LC-ESI/QTOF-MS spectra. The parent ions of these substances are hard to obtain by EI/MS, whereas the protonated molecular ions can be observed clearly by ESI/QTOF-MS. Furthermore, two major characteristic α-cleavages are produced when the EI mode is used, leading to formation of iminium and acylium ions, respectively. These ions can process secondary and tertiary fragmentations, which are very useful in identification. In the case of ESI/QTOF-MS, characteristic fragments are produced via loss of water in cathinones, being secondary amines.The targeted MS/MS mode allows us to identify structures of many unknown substances with certainty. Nevertheless, in order to determine the location of a substituent in a molecule, it is sometimes necessary to use NMR or FTIR.Problems found in identifying novel recreational drugs sold as " legal highs" indicate the need for international collaboration and sharing knowledge and analytical data amongst experts from forensic and clinical laboratories. © 2011 Elsevier Ltd. Source

Czerederecka A.,Institute of Forensic Research
Z Zagadnien Nauk Sadowych | Year: 2013

Expert opinion is admissible as evidence in court and is therefore subject to evaluation. The question that immediately follows, however, is that of how and to what extent a court can control and evaluate the information provided by experts, whose knowledge is, by its very nature, specialised. The law lays down only general, formal requirements for expert opinions (Art. 200 and Art. 201 of the Code of Criminal Procedure and art. 285 § 1 of the Code of Civil Procedure) and, though methodological guidelines are given in a little more detail in the specialist legal literature, it would nevertheless appear essential to also consult the literature of the branches of learning the particular experts represent. In this way the specific nature of the data gathering, and of the grounds upon which the conclusions are drawn, can be taken into account. The aim of this article is to systematise the evaluation criteria for expert psychological opinions. It will first consider the American courts, where the evaluation criteria are distinguished by their orderliness and have a long tradition: the Frye standard of 1923, the Federal rules on the Admissibility of evidence of 1976 and the daubert standard of 1993. American forensic psychology takes into consideration guidelines specific to the conditions of the experts' work, which emphasise the specific nature of the interpersonal relationships involved and the ethical problems they entail: the Heilbrun model of 1992 and the Marlowe model of 1995. Polish court procedure does not yet possess such an homogenous system of evaluation and - considering the differences in legal systems and cultural conditioning - consideration is required in deciding which of the American experiences can be applied in Poland. The article then presents guidelines for the evaluation of expert evidence as they are found in the Polish legal literature (Tomaszewski, Widła, Wójcikiewicz), as well as ten psychological criteria formulated by the author in 2005 based on the methodological and ethical requirements obligatory in psychological research and on the guidelines found in the forensic psychology literature. These may serve as a starting point in the systematisation of expert psychological opinion in court and, therefore, be of use both to the agencies that request such opinions and to the experts who prepare them. © by the Institute of Forensic Research. Source

In this work, a selection of the best features for multivariate forensic glass classification using Scanning Electron Microscopy coupled with an Energy Dispersive X-ray spectrometer (SEM-EDX) has been performed. This has been motivated by the fact that the databases available for forensic glass classification are sparse nowadays, and the acquisition of SEM-EDX data is both costly and time-consuming for forensic laboratories. The database used for this work consists of 278 glass objects for which 7 variables, based on their elemental compositions obtained with SEM-EDX, are available. Two categories are considered for the classification task, namely containers and car/building windows, both of them typical in forensic casework. A multivariate model is proposed for the computation of the likelihood ratios. The feature selection process is carried out by means of an exhaustive search, with an Empirical Cross-Entropy (ECE) objective function. The ECE metric takes into account not only the discriminating power of the model in use, but also its calibration, which indicates whether or not the likelihood ratios are interpretable in a probabilistic way. Thus, the proposed model is applied to all the 63 possible univariate, bivariate and trivariate combinations taken from the 7 variables in the database, and its performance is ranked by its ECE. Results show remarkable accuracy of the best variables selected following the proposed procedure for the task of classifying glass fragments into windows (from cars or buildings) or containers, obtaining high (almost perfect) discriminating power and good calibration. This allows the proposed models to be used in casework. We also present an in-depth analysis which reveals the benefits of the proposed ECE metric as an assessment tool for classification models based on likelihood ratios. © 2011 Elsevier B.V. Source

Wach W.,Institute of Forensic Research
Forensic Science International | Year: 2013

Reconstruction of road accidents combines objective and subjective action. The former concerns science, the latter assessment of human behavior in the context of objective findings. It is not uncommon for experts equipped with an arsenal of tools to obtain similar results of calculations, but to present radically different conclusions about the cause of the accident. The use of sophisticated methods of uncertainty analysis does not guarantee improvement in quality of reconstruction, because, increasingly, the most serious source of reduced reliability of reconstruction is problems in logical inference. In the article the structure of uncertainty and reliability of accident reconstruction was described. A definition of reliability of road accident reconstruction based on the theory of conditional probability and Bayesian network, as a function of modeling, data and expert reliability (defined in the text) was proposed. The uncertainty of reconstruction was made dependent only on the uncertainty of the data. This separation makes it possible to conduct a qualitative and quantitative analysis of reconstruction reliability and to analyze its sensitivity to component parameters, independently of the uncertainty analysis. An example of calculation was presented. The proposed formalism constitutes a tool helpful to explain, among other things, the paradox of reliable reconstruction despite its uncertain results or unreliable reconstruction despite high precision of results. This approach is of great importance in the reconstruction of road accidents, which goes far beyond the analysis of a single, homogeneous subsystem. © 2013 Elsevier Ireland Ltd. Source

Sekula K.,Institute of Forensic Research
Journal of mass spectrometry : JMS | Year: 2012

'Herbal highs' have been advertised as legal and natural substitutes to cannabis, but a detailed examination of these products has revealed that the herbal matrix is laced with synthetic substances that mimic the effects of marijuana. Producers select the ingredients based on the results of scientific studies on the affinities of different chemicals to cannabinoid receptors. Naphthoylindoles have turned out to be the most popular class of substances identified in the products. Legal actions taken in order to tackle the problem of uncontrolled access to one substance have usually resulted in the marketing of derivatives or analogues. In the study, the mass spectral behavior of twelve synthetic cannabinoids from the naphthoylindole family under electrospray ionization (ESI) was investigated. LC-QTOFMS experiments were performed in three modes (low fragmentor voltage, high fragmentor voltage with/without collision energy), and they enabled the identification of protonated molecules and main ions. A general fragmentation pattern under this ionization method was proposed, and mechanisms of ion formation were discussed. The developed procedure allowed the determination of substituent groups of the core naphthoylindole structure and distinction between positional isomers. The obtained results were used for the prediction of the ESI-MS spectra for many naphthoylindoles with a high affinity to cannabinoid receptors. Similarities and differences between ESI-MS and electron impact-MS spectra of naphthoylindoles were discussed. The developed identification process was presented on an example of an analysis of an unknown herbal material, in which JWH-007 was finally identified. Knowledge of the fragmentation mechanisms of naphthoylindoles could also be used by other researchers for identification of unknown substances in this chemical family. Copyright © 2012 John Wiley & Sons, Ltd. Source

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