A common method to estimate the carbon isotopic composition of soil-respired air is to use Keeling plots (delta(13)C versus 1/CO2 concentration). This approach requires the precise determination of both CO2 concentration ([CO2]), usually measured with an infrared gas analyser (IRGA) in the field, and the analysis of delta(13)C by isotope ratio mass spectrometry (IRMS) in the laboratory. We meas...

The use of isotope ratio infrared spectroscopy (IRIS) for the stable hydrogen and oxygen isotope analysis of water is increasing. While IRIS has many advantages over traditional isotope ratio mass spectrometry (IRMS), it may also be prone to errors that do not impact upon IRMS analyses. Of particular concern is the potential for contaminants in the water sample to interfere with the spectroscop...

Previous studies have demonstrated the potential for large errors to occur when analyzing waters containing organic contaminants using isotope ratio infrared spectroscopy (IRIS). In an attempt to address this problem, IRIS manufacturers now provide post-processing spectral analysis software capable of identifying samples with the types of spectral interference that compromises their stable isot...

Rationale The hydrogen isotopic composition of lipids (?2Hlipid) is widely used in food science and as a proxy for past hydrological conditions. Determining the ?2H values large, well-preserved triacylglycerides other microbial lipids, such glycerol dialkyl tetraether (GDGT) thus widespread interest but has so far not been possible due to their low volatility which prohibits analysis by traditi...

Continuous flow analysis using an elemental analyzer interfaced with an isotope ratio mass spectrometer (EA-IRMS) is faster and requires much less material than conventional analytical methods. Although using an EA-IRMS is simple and fast, accurate calibration strongly depends on matching sample and reference peak heights by adjusting the sample weight. This paper describes a new modification f...

We present a rapid and selective method to increase the volatility of tyrosine and phenylalanine without adding derivative C for high-precision gas chromatography-continuous-flow isotope ratio mass spectrometry (GCC-IRMS) based on enzymatic decarboxylation to yield alkylamines and evaluated for 15N isotopic integrity. Purified tyrosine and phenylalanine were converted to tyramine and phenethyla...

Stable hydrogen-isotope ratios (deltaD) of keratin provide a novel means for tracking geographical movements of birds and other species. Here we describe a rapid, low cost, analytical approach to facilitate online continuous-flow isotope-ratio mass spectrometry (CF-IRMS) deltaD analyses of keratins (120-160 samples per day) through the use of calibrated keratin working standards and "comparativ...

In knowledge Economy Times, it’s necessary for knowledge alliance Enterprise (KAE) to build up efficient, reliable information resources management system (IRMS) to make use of the information resources (IR) more availably. This article starts from the characteristics of enterprise information resources (EIR) based on knowledge alliance, analyzing the requirements of establishing IRMS, designin...

Isotope ratio analysis of total organic carbon (TOC) is well-established for the study rivers, lakes, and oceans. Similarly, these aquatic systems are routinely surveyed to quantify natural anthropogenic compounds pollutants, including such things as pharmaceuticals, illicit drugs, phthalates. We merged two approaches demonstrate compound specific isotope (CSIA) on four phthalate esters non-tar...

1. Stable urea isotopes can be used to study urea kinetics in humans. The use of stable urea isotopes for studying urea kinetic parameters in humans on a large scale is hampered by the high costs of the labelled material. We devised a urea dilution for measurement of the distribution volume, production rate and clearance of urea in healthy subjects and renal failure patients using the inexpensi...