Multi-isotopes in human hair: A tool to initiate cross-border collaboration in international cold-cases.

Unidentified human remains have historically been investigated nationally by law enforcement authorities. However, this approach is outdated in a globalized world with rapid transportation means, where humans easily move long distances across borders. Cross-border cooperation in solving cold-cases is rare due to political, administrative or technical challenges.

Characterization of vanillin carbon isotope delta reference materials.

Stable carbon isotope ratio measurements are used to investigate the provenance of vanillin. In this study, a variety of commercial vanillin samples and vanilla products were analyzed to provide a frame of reference for the variability of carbon isotope delta values in various vanillin samples, with the results ranging from -20.6 to -36.

Site-specific carbon isotope measurements of vanillin reference materials by nuclear magnetic resonance spectrometry.

Vanillin, one of the world's most popular flavor used in food and pharmaceutical industries, is extracted from vanilla beans or obtained (bio)-synthetically. The price of natural vanillin is considerably higher than that of its synthetic alternative which leads increasingly to counterfeit vanillin. Here, we describe the workflow of combining carbon isotope ratio combustion mass spectrometry with quantitative carbon nuclear magnetic resonance spectrometry (C-qNMR) to obtain carbon isotope measurements traceable to the Vienna Peedee Belemnite (VPDB) with 0.

Discontinuity in the Realization of the Vienna Peedee Belemnite Carbon Isotope Ratio Scale.

By convention, carbon isotope ratios are expressed relative to VPDB defined by the calcite standard NBS19 in the 1980s. [See T. Coplen, .

Assessing geographic controls of hair isotopic variability in human populations: A case-study in Canada.

Studying the isotope variability in fast-growing human tissues (e.g., hair, nails) is a powerful tool to investigate human nutrition.

Carbon Isotopic Measurements of Nanotubes to Differentiate Carbon Sources.

Stable carbon isotope (δ(C)) analysis can provide information concerning the starting materials and the production process of a material. Carbon nanotubes (CNTs) are produced using a variety of starting materials, catalysts, and production methods. The use of δ(C) as a tool to infer the nature of starting materials to gain insight into the mechanics of CNT growth was evaluated.

Three certified sugar reference materials for carbon isotope delta measurements.

Rationale: For isotope delta analysis, it is preferable to have at least two matrix-matched reference materials whose isotope delta values encompass those of the samples to be analyzed. The National Research Council Canada (NRC) has developed three sugar Certified Reference Materials (CRMs), BEET-1 (beet sugar), GALT-1 (galactose), and FRUT-1 (fructose), to be collectively used for carbon isotope delta measurements in sugars, and other organic materials.

Methods: All materials were homogenized and packaged in glass ampules.

Uncertainty evaluation in normalization of isotope delta measurement results against international reference materials.

Isotope delta measurements are normalized against international reference standards. Although multi-point normalization is becoming a standard practice, the existing uncertainty evaluation practices are either undocumented or are incomplete. For multi-point normalization, we present errors-in-variables regression models for explicit accounting of the measurement uncertainty of the international standards along with the uncertainty that is attributed to their assigned values.

An inter-laboratory comparative study into sample preparation for both reproducible and repeatable forensic 2H isotope analysis of human hair by continuous flow isotope ratio mass spectrometry.

Stable isotope analysis of organic materials for their hydrogen ((2)H), carbon ((13)C), nitrogen ((15)N) or oxygen ((18)O) isotopic composition using continuous flow isotope ratio mass spectrometry (CF-IRMS) is an increasingly used tool in forensic chemical analysis. (2)H isotopic analysis can present a huge challenge, especially when dealing with exhibits comprising exchangeable hydrogen such as human scalp hair. However, to yield forensic data that are fit for purpose, analysis of the (2)H isotopic composition of the same homogeneous human hair sample by any laboratory worldwide must yield the same isotopic composition within analytical uncertainty.

Proteomic and transcriptomic analyses reveal genes upregulated by cis-dichloroethene in Polaromonas sp. strain JS666.

Polaromonas sp. strain JS666 is the only bacterial isolate capable of using cis-dichloroethene (cDCE) as a sole carbon and energy source. Studies of cDCE degradation in this novel organism are of interest because of potential bioremediation and biocatalysis applications.

An approach for assessing total instrumental uncertainty in compound-specific carbon isotope analysis: implications for environmental remediation studies.

Determination of compound-specific carbon isotope values by continuous flow isotope ratio mass spectrometry is impacted by variation in several routine operating parameters of which one of the most important is signal size, or linearity. Experiments were carried out to evaluate the implications of these operating parameters on both reproducibility and accuracy of delta13C measurements. A new method is described for assessing total instrumental uncertainty of routine compound-specific delta13C analysis, incorporating both accuracy and reproducibility.

Stable isotope evidence for biodegradation of chlorinated ethenes at a fractured bedrock site.

Stable carbon isotope analysis of chlorinated ethenes and ethene was performed at a site contaminated with trichloroethene (TCE), a dense non-aqueous phase liquid (DNAPL). The site is located in fractured bedrock and had variable groundwater hydraulic gradients during the study due to a local excavation project. Previous attempts to biostimulate a pilot treatment area at the site resulted in the production of cis-1,2-dichloroethene (cis-DCE), the first product of reductive dechlorination of TCE.

Carbon isotopic fractionation during aerobic vinyl chloride degradation.

Vinyl chloride (VC) is a carcinogenic contaminant commonly found in groundwater. Much research has focused on anaerobic reductive dechlorination of VC, and recently on aerobic VC degradation. In this study, the stable carbon isotope enrichment factor associated with aerobic VC assimilation was determined for Mycobacterium sp.