Combination of stable isotope ratio data and chromatographic impurity signatures as a comprehensive concept for the profiling of highly prevalent synthetic cannabinoids and their precursors.

In this study, we utilized elemental analyser (EA) and gas-chromatography (GC) isotope ratio mass spectrometry (IRMS) and ultra-high-performance liquid chromatography coupled to mass spectrometry (UHPLC-MS) in a comprehensive profiling approach assessing the chromatographic impurity signatures and δ13C and δ15N isotope ratios of synthetic cannabinoids from police seizures and internet test purchases. Main target of this study was the highly prevalent synthetic cannabinoid MDMB-CHMICA (methyl (2S)-2-([1-(cyclohexylmethyl)-1H-indol-3-yl]formamido)-3,3-dimethylbutaoate). Overall, 61 powder and 118 herbal blend (also called "Spice-Products") samples were analysed using both analytical techniques and evaluated in a joint model to link samples from a common source. As a key finding, three agglomerates of Spice-product samples with similar dates of purchase were identified in the IRMS data, possibly representing larger shipments of MDMB-CHMICA, each produced with the same precursor material, successively delivered to the European market. The three agglomerates were refined into multiple sub-clusters based on the impurity profiling data, each representing an individual synthesis batch. One of the agglomerates identified in the IRMS data was found to consist two groups of four sub-clusters, respectively, with majorly different impurity profiles, demonstrating the necessity for both analytical techniques to extract the maximum amount of information from a limited sample pool. Additionally, 31 samples containing the recently surfaced synthetic cannabinoid Cumyl-PeGaClone (5-pentyl-2-(2-phenylpropan-2-yl)-2,5-dihydro-1H-pyrido[4,3-b]indol-1-one) were analysed for their and δ13C and δ15N isotope ratios to put the isotopic data recorded for MDMB-CHMNICA in a more global perspective. Three building blocks of precursor chemicals (indole, tert-leucine, cumylamine) potentially used for the synthesis of the two named synthetic cannabinoids were acquired from different global vendors and measured for their δ13C and δ15N isotope ratios to better understand variations in the isotopic composition of the synthetic cannabinoids and to trace their origin.

Same, same but different!-matching entomological traces to a human food source by stable isotope analysis.

Blow flies are important tools in forensic entomology, as they feed and develop on human bodies. This fact can be used to estimate the minimum post mortem interval (PMImin), by classifying the age of the immature stages found on corpses. The capacity to also be able to classify the age of adult flies, or even empty puparia, could increase the timeframe for a PMImin. However, the association of older developmental stages, such as adult flies or their empty cases, with a human cadaver may be challenged, as such specimens could stem from another food source. Analyzing the stable carbon (δ13C) and nitrogen (δ15N) isotopes in such specimens could be helpful here, as the isotope signatures reflect those of the food sources. We compared the δ15N and δ13C signatures of tissue from humans and 12 additional species by elemental analyzer-isotope ratio mass spectrometry (EA-IRMS). We did the same for adult flies and empty puparia of the blow fly Lucilia sericata, which were derived from juvenile stages developed on tissues from the mentioned species. The isotope signatures for the adult flies and their empty puparia linearly mirrored the isotope signatures for the respective tissues on which they developed as larvae. Results such as these are useful to indicate the flies' nutritional history, but they do not provide the same kind of evidence that a DNA analysis would. As individual dietary habits, global distribution and environmental effects can influence isotope ratios, we strongly recommend to analyzing entomological traces and muscle tissues of potential donors or for other food sources.

Global spatial distributions of nitrogen and carbon stable isotope ratios of modern human hair.

RATIONALE: Natural stable carbon (δ(13)C) and nitrogen isotope ratios (δ(15)N) of humans are related to individual dietary habits and environmental and physiological factors. In forensic science the stable isotope ratios of human remains such as hair and nail are used for geographical allocation. Thus, knowledge of the global spatial distribution of human δ(13)C and δ(15)N values is an essential component in the interpretation of stable isotope analytical results. METHODS: No substantial global datasets of human stable isotope ratios are currently available, although the amount of available (published) data has increased within recent years. We have herein summarised the published data on human global δ(13)C andδ(15)N values (around 3600 samples) and added experimental values of more than 400 additional worldwide human hair and nail samples. In order to summarise isotope ratios for hair and nail samples correction factors were determined. RESULTS: The current available dataset of human stable isotope ratios is biased towards Europe and North America with only limited data for countries in Africa, Central and South America and Southeast Asia. The global spatial distribution of carbon isotopes is related to latitude and supports the fact that human δ(13)C values are dominated by the amount of C4 plants in the diet, either due to direct ingestion as plant food, or by its use as animal feed. In contrast, the global spatial distribution of human δ(15)N values is apparently not exclusively related to the amount of fish or meat ingested, but also to environmental factors that influence agricultural production. CONCLUSIONS: There are still a large proportion of countries, especially in Africa, where there are no available data for human carbon and nitrogen isotope ratios. Although the interpretation of modern human carbon isotope ratios at the global scale is quite possible, and correlates with the latitude, the potential influences of extrinsic and/or intrinsic factors on human nitrogen isotope ratios have to be taken into consideration.

Forensic investigation of brick stones using instrumental neutron activation analysis (INAA), laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and X-ray fluorescence analysis (XRF).

Brick stones collected from different production facilities were studied for their elemental compositions under forensic aspects using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), instrumental neutron activation analysis (INAA) and X-ray fluorescence analysis (XRF). The aim of these examinations was to assess the potential of these methods in forensic comparison analyses of brick stones. The accuracy of the analysis methods was evaluated using NIST standard reference materials (679, 98b and 97b). In order to compare the stones to each other, multivariate data analysis was used. The evaluation of the INAA results (based on the concentrations of V, Na, K, Sm, U, Sc, Fe, Co, Rb and Cs) using principal component analysis (PCA) and cluster analysis is presented as an example. The results derived from the different analytical methods are consistent. It was shown that elemental analysis using the described methods is a valuable tool for forensic examinations of brick stones.