A rapid gas chromatography-tandem mass spectrometry (GC-MS/MS) analytical method was developed for the simultaneous analysis of 7 estrogenic hormones (17α-estradiol, 17β-estradiol, estrone, mestranol, 17α-ethynylestradiol, levonorgestrel, estriol) and 5 androgenic hormones (testosterone, androsterone, etiocholanolone, dihydrotestosterone, androstenedione) in aqueous matrices. This method is uni...

The volatile and polar solvent 1,4-dioxane has recently been reported as a contaminant of ground and surface waters, establishing the need to determine this substance in drinking water. This investigation established that 1,4-dioxane can be determined in water by various techniques including direct aqueous injection (DAI) gas chromatography (GC) and purge and trap GC-mass spectrometry (MS). Pur...

Pioneer communities establishing themselves in the barren terrain in front of glacier forelands consist principally of predator species such as carabid beetles and lycosid spiders. The fact that so many different predators can co-inhabit an area with no apparent primary production was initially explained by allochthonous material deposited in these forelands. However, whether these populations ...

Literature data on H /D isotope effects on polarizability are reviewed. An argument based on perturbation theory correlates the isotopic differences with electronic transition moments via vibra­ tional averaging. The contribution of the second moment isotope effect is especially important. The approach is first illustrated with a calculation on H 2/D 2 and then employed to correlate differentia...

Owing to its importance as a serum electrolyte, sodium is determined routinely in clinical laboratories. In the United States, the accuracy of these measurements is assessed through a number of proficiency testing programs. Clinical measurements are supported by the National Institute of Standards and Technology through the production of serum matrix Standard Reference Materials (909 and 956 se...

Robust quantification of analytes is a prerequisite for meaningful metabolomics experiments. In non-targeted metabolomics it is still hard to compare measurements across multiple batches or instruments. For targeted analyses isotope dilution mass spectrometry is used to provide a robust normalization reference. Here, we present an approach that allows for the automated semi-quantification of me...

Large-scale patterns of isotope ratios are detectable in the tissues of organisms, but the variability in these patterns often obscures detection of environmental trends. We show that plants and animals at lower trophic levels are relatively poor indicators of the temporal trend in atmospheric carbon isotope ratios (delta13C) when compared with animals at higher trophic levels. First, we tested...

Introduction: Dauphas et al. [1] and Yin et al. [2] reported molybdenum isotopic anomalies in bulk undifferentiated and differentiated meteorites and this was the first time that isotopic anomalies were found on the scale of a meteorite hand-specimen. Even more recently, Chen and Papanastassiou [3,4] identified ruthenium isotopic anomalies in meteorites. Dauphas et al. [5] used theoretical prod...

We demonstrate the detection and quantification of isotopes from solid samples remotely at a distance 36 m. This was accomplished through combination femtosecond filaments laser ablation molecular isotopic spectrometry (F 2 -LAMIS). Isotopically enriched graphite with varying 13 C concentration were used F -LAMIS emission measured using fieldable spectrometer system. A standardless approach to ...

A method has been developed for the determination of eight N-nitrosamines in drinking water and treated municipal effluent. The method uses solid phase extraction (SPE), gas chromatography (GC) and analysis by tandem mass spectrometry (MS-MS) with electron ionization (EI). The target compounds are N-nitrosodimethylamine (NDMA), N-nitrosomethyethylamine (NMEA), N-nitrosodiethylamine NDEA), N-nit...