Time filter

Source Type

Schweitenkirchen, Germany

Lehn C.,Ludwig Maximilians University of Munich | Rossmann A.,Isolab GmbH | Graw M.,Ludwig Maximilians University of Munich
Science and Justice | Year: 2015

Stable isotope methods can be used to determine the provenance of unidentified corpses. Body tissue materials such as teeth, bone, hair and nail taken from mortal remains provide information of different time periods of an individuals' life from childhood to death. Tissues of newborns contain provenance information of different time periods during pregnancy of the child's mother. The results of stable isotope analyses of body residues of two adults and a newborn found in Germany between 2010 and 2012 are presented. To determine the geographic origin and movements of unknown individuals, stable isotopes of hydrogen, carbon, nitrogen and sulphur were analysed in hair and bone collagen samples. Amino acid composition and, as a consequence, δ2H, δ13C, δ15N, and δ34S values in human keratin and bone collagen are different. Consequently correction factors were determined to compare isotopic data of bone collagen with those of an extensive worldwide reference hair collection. The isotopic signatures in hair and in bone collagen samples were compared to geographical groups of reference hair samples by canonical discriminant analysis. The results served as the basis for providing provenance constraints for the unidentified persons as requested by the police and prosecution. Ultimately the individuals were identified; hence the isotopic provenance interpretations can be critically evaluated and are shown to be successful. © 2014 Forensic Science Society. Source

Lehn C.,Ludwig Maximilians University of Munich | Lihl C.,Ludwig Maximilians University of Munich | Rossmann A.,Isolab GmbH
Isotopes in Environmental and Health Studies | Year: 2015

To receive information about the duration of a person's stay abroad related to those questions in forensics, stable isotopes of H–C–N–S were analysed in beard hair samples from four young soldiers, who went from Fürstenfeldbruck (Bavaria, Germany) to Phoenix (Arizona, USA) on the same date for their pilot training over a time period of 3 months. All study subjects were almost of the same age, had similar physical constitutions and stayed at the same military bases for the whole study period. However, the results showed considerable individual variabilities. In Arizona, hair δ13C increased by 2.3 ‰ (±0.6) and δ34S decreased by 1.8 ‰ (±1.2). No remarkable shifts of hair δ15N and δ2H were observed. Significant shifts of δ13C or δ34S in the shaved beard hair samples occurred 8 or 9 days after arrival in Arizona, respectively. The time lag to receive the isotope signals in hair due to US diet correspond to the growth period that hair needs to cover the distance of 2–3 mm from its root to the surface of the skin. This implies that isotopic changes due to the consumption of food and drinks were incorporated almost immediately into the hair protein. Consequently, if connected with an isotopic change of the diet, short-term stays for only a few days might be clearly recognizable within the first millimetres of a scalp hair strand which includes the hair roots. © 2015, © 2015 Taylor & Francis. Source

Lehn C.,Ludwig Maximilians University of Munich | Mutzel E.,Ludwig Maximilians University of Munich | Rossmann A.,Isolab GmbH
International Journal of Legal Medicine | Year: 2011

This paper presents a comparison of the isotopic ratios of hydrogen, carbon, nitrogen and sulphur of three pairings of hair and nail tissue taken from contemporary human remains. Our aim was to examine the possibility of a direct comparison of isotopic data in hair with that of nail tissue for forensic purposes. The results indicate that stable isotope ratios of the elements were best comparable between human scalp hair longer than 3 cm and the distal end of the nails. There were no distinct variations between finger and toenails. Our isotopic data for bulk hair and nail confirmed that hair samples were slightly enriched in 13C but depleted in 15N compared to nail samples. Furthermore, our data reveal that δ34S values in nail samples were more variable than in hair samples. Direct comparison of the corresponding segments of hair and nail samples may be difficult due to individual differences especially for δ15N and δ2H. Hair may have an isotopic composition more consistent with the ingested food within a specific time than is provided by nail. It can be concluded that once a hair is formed, no further metabolic changes of the isotopic pattern should occur. Nevertheless, our data suggest that there was a change in isotope ratios particularly for δ2H along the hair shaft. Interpretation of the isotope data in corresponding segments of hair and nail for forensic purposes must consider particular variations, especially for chronological considerations. © 2011 Springer-Verlag. Source

Harrison S.M.,Agriculture and Food Science Center | Schmidt O.,Agriculture and Food Science Center | Moloney A.P.,Teagasc | Kelly S.D.,UK Environment Agency | And 5 more authors.
Food Chemistry | Year: 2011

Multiple stable isotope ratios (δ2H, δ13C, δ18O and δ34S) were measured in muscle, muscle lipids and lipid fractions collected from 28 lambs, subjected to a diet-switch and raised on two energy allowances (EAs), to determine tissue turnover and diet-tissue fractionation. The diet-muscle fractionations prior to the diet-switch were estimated to be -44.0‰, +1.9‰ and 0‰ for H, C and S, respectively, while the drinking water was demonstrated to be the main source of muscle O and thus δ18O variation. The diet-intra-muscular lipid fractionations prior to the diet-switch were estimated to be -172.7‰, -1.3‰ and -11.5‰ for H, C and O, respectively. The C half-lives of muscle were determined to be 75.7 and 91.6days for animals receiving the high and low EA, respectively. Extracting temporally resolved pre-slaughter dietary information from meat by analysing bulk muscle, muscle lipids and muscle lipid fractions appeared to be not practicable due to possible incomplete turnover of lipids. © 2010 Elsevier Ltd. Source

Camin F.,IASMA Edmund Machinery Foundation | Perini M.,IASMA Edmund Machinery Foundation | Bontempo L.,IASMA Edmund Machinery Foundation | Fabroni S.,Italian Agricultural Research Council | And 9 more authors.
Food Chemistry | Year: 2011

Several isotopic (13C/12C, 15N/14N, 18O/16O, 2H/1H, 34S/32S) and chemical-physical parameters (pH, fruit weight, juice yield, titratable acidity, total soluble solids, skin resistance, flesh firmness, colorimetric characteristics, weight loss after harvesting, antioxidant activity, earliness index, total nitrogen, ascorbic acid, synephrine, anthocyanins and polyphenols, citric acid, malic acid, sucrose, glucose and fructose content) were investigated as potential markers of organically cultivated oranges, clementines, strawberries and peaches produced in Italy between 2006 and 2008, in experimental fields and in certified farms. The ratio 15N/14N, ascorbic acid and total soluble solids were shown to be the most significant variables for distinguishing between organically and conventionally cultivated fruits. It was not possible to define general threshold limits typical of organic fruits because these parameters are influenced also by fruit specie, cultivar, year and site of production. Combining isotopic and chemical markers a good discrimination between organic and conventional fruits of different species was achieved. © 2010 Elsevier Ltd. Source

Discover hidden collaborations