Natural abundance measurements

Martin A, Mariotti A, Balesdent J, Lavelle P, Vuattoux R (1990) Estimate of organic matter turnover rate in savanna soil by 13C natural abundance measurements. Soil Biol Biochem 22 517-523... 

Table 1. Natural abundances, measured isotope ratios, and enrichment factors used for Calcium isotopes.

The foregoing review is centered on natural-abundance measurements of stable isotopes. In many cases, however, several potential foods or prey items are indistinguishable in their natural-abundance isotopic ratios, and thus isotopic analyses provide poor resolution. One strategy for overcoming this problem is to purposefully manipulate the isotopic ratios in one or more... 

While the agreement of our natural abundance measurements with the best measured values are quite good, the average relative standard deviation of measurements by our method is about 0 2% compared to about 0 1% for the best measured values It is important to note, however, that our measurements are well within error limits that might reasonably be expected from measurements of a biological system Our method, while a modification of that used to produce the best measured values (4), has introduced some simplifications to the sample workup that speed sample processing ... 

Prior to isotopic analysis, either for natural abundance measurements or at the end of tracer incubations, the relevant N pools must be isolated. Here we review the isolation of the most important N fractions PN, NH4+, NOs, NO2, DON, and urea. 

Natural abundance measurements are made against a standard, atmospheric N2 in the case of measurements, and are expressed in delta S) units ... 

The increasing availabihty of mass spectrometers and on-Hne interfaces for sample preparation has made natural abundance measurements accessible to a broad community of biological oceanographers, and stable isotope measurements are becoming a routine tool in studies of marine ecosystems. In general, measurements are now carried out with continuous flow systems that integrate a... 

Mariotti, A. (1983). Atmospheric nitrogen as a reliable standard for natural abundance measurements. Nature 303, 685—687. 

The ability to perform natural-abundance measurements on individual compounds has only recently been achieved. This capability arose from refinements... 

Faijon and co-workers have introduced the sensitivity optimized SOFAST-HMBC technique, which is a phase sensitive echo/anti-echo HMBC with selective pulses applied to H. The technique allows the natural abundance measurement of Ynh oc in peptides with values lower than 1 Hz. 

---