A continuous flow method (CF-IRMS) for the rapid determination of the sulfur isotope composition of sulfide and sulfate minerals has significant advantages over the classic extraction method in terms of the reduced sample quantity and a rapid analytical cycle of less than 8 min/ analysis. For optimum performance, the technique is sensitive to a number of operating parameters, including sample w...

The behavior in vivo of transferrin in loading and unloading iron from its two sites was examined in rats. Radioiron entering the plasma from the gastrointestinal tract in iron-deficient, normal and iron-loaded rats did not differ in its subsequent tissue distribution between erythroid marrow and liver of normal recipients from a second isotope added to the same plasma in vitro. Loading studies...

We describe a continuous-flow isotope ratio mass spectrometry (CF-IRMS) technique for high-precision δD and δ13C measurements of atmospheric methane on 40 mL air samples. CH4 is separated from other air components by utilizing purely physical processes based on temperature, time and mechanical valve switching. Chemical agents are avoided. Trace amounts of interfering compounds can be separated ...

Five marijuana samples were compared using bulk isotope analysis compound-specific isotope ratio analysis of the extracted cannabinoids. Owing to the age of our cannabis samples, four of the five samples were compared using the isotope ratios of cannabinol (CBN), a stable degradation product of Δ(9)-tetrahydrocannabinol (THC). Bulk δ(13)C isotope analysis discriminated between all five samples ...

Stable isotope ratios of hydrogen and oxygen in microbes have been shown to be functions of the corresponding isotope ratios of the water with which the culture medium was prepared, and thus to contain a potential geographic signal. Water can evaporate from agar (solid) media during culturing, changing its isotope ratios. Here we describe the effect of drying on the isotope ratios of water extr...

In order to investigate chlorine isotope behaviour, it was necessary to develop analytical methods and methods for data interpretation. The accuracy, precision and amount dependency of chlorine isotope ratio analyses performed with gas chromatography quadrupol mass-spectrometry (GC-qMS) were evaluated for two Agilent and Thermo instruments. The calibration of raw data to SMOC scale (Standard Me...

The abundances of neon and several other isotopic ratios in the galactic cosmic rays (GCRs) have been measured using data from the Cosmic Ray Isotope Spectrometer (CRIS) aboard the Advanced Composition Explorer (ACE). We have derived the Ne/Ne ratio at the cosmic-ray source using the measured Ne, F, and O abundances as “tracers” of secondary isotope production. Using this approach, the Ne/Ne ab...

The second point makes the matrix matching of standards to samples for direct analysis impossible and, in order to normalize all samples to a similar matrix, the analysis of a diluted (or digested) solution is preferable. High instrumental sensitivity is then required to reliably measure the resulting single digit pg g-1 uranium concentrations. While the quantification of uranium is therefore d...

Isotope ratio analyses of atmospheric CO(2) at natural abundance have significant potential for contributing to our understanding of photosynthetic and respiration processes in forest ecosystems. Recent advances in isotope ratio mass spectrometry allow for rapid, on-line analysis of small volumes of CO(2) in air, and open new research opportunities at the ecophysiological, whole-organism, and a...

[1] The Madden‐Julian Oscillation (MJO) is the dominant mode of intraseasonal variability in the tropical atmosphere. This study examines the evolution of the hydrologic regime from before the onset of the MJO (pre‐onset period) to the MJO onset period, using deuterated water vapor (HDO) measurements from the Tropospheric Emission Spectrometer (TES) and from ground‐based stations. Ground‐based ...