Determination of the Isotopic Composition of Indium by MC-ICP-MS Using an Improved Measurement Model for the Gravimetric Isotope Mixture Method.

In this study, we report the first independent and primary isotope ratio measurement of indium by MC-ICP-MS, utilizing gravimetric isotope mixtures of two near-pure enriched indium isotopes. Consistent with previous findings, we observe that the traditional one-mixture-at-a-time calibration approach can introduce a strong dependence of the resulting isotope ratio correction factors on the composition of the mixtures. Our analysis suggests that this is due to biases inherent in measuring the isotopic composition of pure isotopic materials.

Site-specific hydrogen isotope measurements of vanillin by H-qNMR and GC-IRMS.

Stable isotope analyses are powerful techniques to detect counterfeiting of food products, especially in vanillin, one of the world's most popular flavors used in food and pharmaceutical industries. Although a stable carbon isotopic ratio provides an invaluable new source of isotopic information, the analysis of the hydrogen site-specific (H/H) isotopic distribution in vanillin gives valuable complementary isotopic information allowing a complete isotopic fingerprint of the vanillin molecule for authentication. However, there are only a limited number of studies that compare the validity of the results obtained by IRMS and NMR.

Stable Isotope Reference Materials and Scale Definitions-Outcomes of the 2024 IAEA Experts Meeting.

The participants of the 12 International Atomic Energy Agency (IAEA) meeting on stable isotope reference materials reached a consensus, acknowledging the existence and use of two carbon isotope delta scales: the VPDB (Vienna Peedee belemnite) scale and the VPDB-LSVEC (LSVEC - lithium carbonate prepared by H. J. Svec).

Comparison of Carbon Isotope Ratio Measurement of the Vanillin Methoxy Group by GC-IRMS and C-qNMR.

Site-specific carbon isotope ratio measurements by quantitative C NMR (C-qNMR), Orbitrap-MS, and GC-IRMS offer a new dimension to conventional bulk carbon isotope ratio measurements used in food provenance, forensics, and a number of other applications. While the site-specific measurements of carbon isotope ratios in vanillin by C-qNMR or Orbitrap-MS are powerful new tools in food analysis, there are a limited number of studies regarding the validity of these measurement results. Here we present carbon site-specific measurements of vanillin by GC-IRMS and C-qNMR for methoxy carbon.

Isotopic measurements of carbon dioxide: the role of measurement science and standards.

Isotopic measurements provide valuable information about the origin of greenhouse gases - as carbon dioxide levels increase, there is a corresponding shift towards lighter isotopic composition similar to that of fossil fuels. Detecting such isotopic shifts, however, requires extremely precise measurements, which must also be globally reproducible in order to make reliable policy decisions. This feature article outlines the collective search for the ideal standard for carbon isotope measurements since the 1950s.

Preparation of O-labelled azaspiracids for accurate quantitation using liquid chromatography-mass spectrometry.

Azaspiracids (AZAs) are a group of polyether marine algal toxins known to accumulate in shellfish, posing a risk to human health and the seafood industry. Analysis of AZAs is typically performed using LC-MS, which can suffer from matrix effects that significantly impact the accuracy of measurement results. While the use of isotopic internal standards is an effective approach to correct for these effects, isotopically labelled standards for AZAs are not currently available.

Production and certification of BOTS-1: bovine muscle-certified reference material for incurred veterinary drug residues.

A freeze-dried bovine muscle-certified reference material (CRM), known as BOTS-1 (DOI: https://doi.org/10.4224/crm.

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.

Production and stability of Oxygen-18 labeled Caribbean ciguatoxins and gambierones.

Ciguatoxins (CTXs) and gambierones are ladder-shaped polyethers associated with ciguatera poisoning and Gambierdiscus spp. Several of these compounds contain carbonyl or hemiketal groups, which have the potential to exchange with O-labeled water under acidic conditions. The effects of solvent composition and acid on the rate of exchange and on the stability of the labels at various pH values were assessed to optimize the incorporation of O into Caribbean ciguatoxin-1 and -2 (C-CTX1/2), gambierone, and 44-methylgambierone.

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, .

Determination of the Isotopic Composition of Zirconium Using MC-ICPMS and a Regression Model for Mass Bias Correction.

Measurements of zirconium isotopes provide insights into the formation of planetary bodies, dating nuclear explosions, or maintenance of nuclear reactors. Although many comparative measurements for the isotopic composition of zirconium have been performed using mass spectrometry, there is a lack of zirconium isotopic reference materials and only a single calibrated measurement has been reported to date by total evaporation thermal ionization mass spectrometry (TE-TIMS). In this study, we report an independent measurement of full zirconium isotopic composition in a new zirconium isotopic reference material by multicollector inductively coupled plasma MS using the regression method and two independent certified isotopic reference materials, NIST SRM 984 Rb and NIST SRM 987 Sr.