Spectroscopic analysis of bones for forensic studies ☆ Mirko Tofanelli a , Lorenzo Pardini b , Matteo Borrini c , Fulvio Bartoli d , Alessandra Bacci d , Alessandro D’Ulivo a , Emanuela Pitzalis a , Marco Carlo Mascherpa a , Stefano Legnaioli a , Giulia Lorenzetti a , Stefano Pagnotta a , Gildo de Holanda Cavalcanti e , Marco Lezzerini f , Vincenzo Palleschi a, ⁎ a Applied and Laser Spectroscopy Laboratory, Institute of Chemistry of Organometallic Compounds, Research Area of CNR, Via G. Moruzzi, 1, 56124 Pisa, Italy b Institut für Physik und IRIS Adlershof, Humboldt-Universität zu Berlin, Zum Großen Windkanal 6, 12489 Berlin, Germany c Research Centre in Evolutionary Anthropology and Palaeoecology, School of Natural Sciences and Psychology, Liverpool John Moores University, Byrom Street, Liverpool, UK d Department of Biology, University of Pisa, Via A. Volta, 4, 56126 Pisa, Italy e Instituto de Fìsica, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/nº Campus da Praia Vermelha, CEP 24210-346, Niterói, Rio de Janeiro, Brazil f Department of Earth Sciences, University of Pisa, Via Santa Maria, 53, 56126 Pisa, Italy abstract article info Article history: Received 30 December 2013 Accepted 5 June 2014 Available online 23 June 2014 Keywords: LIBS Forensic analysis Bones The elemental analysis of human bones can give information about the dietary habits of the deceased, especially in the last years of their lives, which can be useful for forensic studies. The most important requirement that must be satisfied for this kind of analysis is that the concentrations of analyzed elements are the same as ante mortem. In this work, a set of bones was analyzed using Laser-Induced Breakdown Spectroscopy (LIBS) and validated using Inductively Coupled Plasma–Optical Emission Spectroscopy (ICP-OES), in order to compare those two tech- niques and to investigate the effect of possible alterations in the elemental concentrations' proportion resulting from the treatment usually applied for preparing the bones for traditional forensic analysis. The possibility that elemental concentrations' changes would occur after accidental or intentional burning of the bones was also studied. © 2014 Elsevier B.V. All rights reserved. 1. Introduction The compositional analysis of human bone tissue is a common prac- tice in forensic science, since the information that could be gathered often allows to distinguish among different individuals or classify the remains in broad classes [1,2]. The concentration of trace elements in bones, in fact, can be related to the dietary habits of the deceased [3]. Such elements are involved in a number of metabolic processes, and they are finally accumulated in the bone tissue [4]. The analysis of the trace elements in bones is usually performed using standard techniques laboratory techniques such as Atomic Absorption Spectroscopy (AAS) [5] or Inductively Coupled Plasma (ICP), either coupled to optical emis- sion spectroscopy (ICP-OES) [6] or mass spectroscopy (ICP-MS) [7] for detection and a laser for sampling (Laser-Ablation ICP) [8]. More recent- ly, Laser-Induced Breakdown Spectroscopy (LIBS) [9] has been pro- posed as a viable method for trace element analysis in human tissues (hair [10], nails [11], malignant tissues [12,13]) as well as bone tissue [14,15]. The main advantage of LIBS, with respect to the other more con- solidated techniques, would be the capability of analyzing minimal amounts of the sample, without the need for any kind of preparation, with relatively cheap instrumentation. Such peculiar characteristics would result, according to the specific needs of the forensic investiga- tion, in the possibility of operating in situ, on very small bone fragments or and/or acquiring information on many different samples in a very short time while preserving the samples for further analysis, when needed. However, it is known that LIBS can be substantially affected by the so-called matrix effect [9], i.e. the strong dependence of the LIBS signal of a given element on the physical and chemical characteris- tics of the sample matrix. Although the matrix effect could be overcome using standardless analytical methods, such as the Calibration-Free LIBS approach [16], from the point of view of the speed and simplicity of the analysis would be highly desirable to assess the feasibility of a ‘classical’ calibration approach to LIBS analysis, ideally using just a few standards, eventually realized using a method similar to the one recently proposed by Bertuccelli et al. [17]. Although LIBS analysis does not require any treatment of the sample, the bone tissue to be analyzed could have undergone a number of modifications, with respect to the pre-mortem status, before reaching the laboratory for the analysis. These modifications could be associated to the cause of death (fire-related deaths, for example) or to post- mortem fire injuries from crime concealing arson [18] although, in prin- ciple, the effect of the standard thermal treatments used for flesh re- moval from the bones [19] could also produce changes in the sample matrix and, thus, could affect the LIBS analysis. Spectrochimica Acta Part B 99 (2014) 70–75 ☆ Selected paper from the 7th Euro-Mediterranean Symposium on Laser Induced Breakdown Spectroscopy (EMSLIBS 2013), Bari, Italy, 16–20 September 2013. ⁎ Corresponding author. E-mail address: vincenzo.palleschi@cnr.it (V. Palleschi). http://dx.doi.org/10.1016/j.sab.2014.06.006 0584-8547/© 2014 Elsevier B.V. All rights reserved. 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