Stable isotope ratios

The ratio of certain stable isotopes, principally 13C/12C and 180/160, varies with geographical location where climatic effects change the proportions of the isotopes available to plants. Stable isotope measurements can be carried out 

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In recent years, together with enantioselective analysis, the determination of the natural abundance of stable isotopes by means of stable isotope ratio mass spectrometry (TRMS) can be very useful for the assignment of the origin of foods and food ingredients, and of authenticity evaluation (24). 

Air N2 is well-mixed, and acts as a very large reservoir both factors buffer against much variability in the stable isotope ratios of Nj (Mariotti 1983). 

NOTE ADDED IN PROOF This manuscript had been submitted shortly after the presentation of the paper at the Fourth Advanced Seminar on Pale-odiet, 1994. Ongoing research, especially stable isotope analysis of single amino acids from inoculated and non-inoculated marten bones (same specimens as in this paper) further and strongly support our conclusion that bacterial modifica-tion causes substantial shifts in collagen stable isotope ratios (Balzer et fl/. 1997). 

This research project was financially supported by the BMBE We are most indebted to Prof. Dr. H.-L. Schmidt, Technical University of Munich, for the measurement of stable isotope ratios and his advice and comments. Text edited by Siew Eiselt. 

Effect of trophic level on stable isotope ratios of bone collagen... 

Huelsemann F., Flenker, U., Koehler, K, Schaenzer, W. (2009). Effect of a controlled dietary change on carbon and nitrogen stable isotope ratios of human hair. Rapid Communications in Mass Spectrometry Vol 23, pp. 2448-2454. 

The influence of environmental water on the hydrogen stable isotope ratio in aquatic consumers. Oecologia, Vol. 161, pp. 313-324. 

Walter, W.D. Leslie, Jr., D.M. (2009). Stable isotope ratio analysi to differentiate temporal diets of a free-ranging herbivore. Rapid Communications in Mass Spectrometry, Vol. 23, pp. 2190-2194. (http //dx.doi.org/10.1002/rcm.4135)... 

Farquhar, G.D., Hubick, K.T., Condon, A.G. Richards, R.A. (1988). Carbon isotope fractionation and plant water-use efficiency. In Applications of Stable Isotope Ratios to Ecological Research, ed. P.W. Rundel, J.R. Ehleringer K.A. Nagy, pp.21 0. New York Springer-Verlag. 

Schade, J. E., Marsh, G. L., and Eckert, J. E. (1958). Diastatic activity and hydroxymethylfur-fural in honey and their usefulness in detecting heat adulteration. Food Res. 23, 446-463. Schellenberg, A., Chmielus, S., Schlicht, C., Camin, F., Perini, M., Bontempo, L., Heinrich, K., Kelly, S. D., Rossmann, A., Thomas, F., Jamin, E., and Horacek, M. (2010). Multielement stable isotope ratios (H, C, N, S) of honey from different European regions. Food Chem. 121, 770-777. 

Barrie, A., Bricout, J. and Koziet, J. (1984) Gas chromatography stable isotope ratio analysis at natural abundance levels. Biomedical Mass Spectrometry 11, 439 447. 

Non-quantitative sample preparation, e.g., conversion to C02 provides two opportunities for bias. First, if the sample is a pure substance, such as methane or cellulose, isotopic fractionation can take place. Correction, using the stable isotope ratio 13C/12C, is possible provided the initial 13C concentration is... 

Any of these data banks, those parts from the ice ages, can have their stable isotope ratios perturbed by the huge ice reserves which were removed from the sea and piled up on land, because the ice depletes the oceans in the light isotopes, and therefore significantly enriches the sea in the heavy isotopes, so that sea sediments and continental precipitation, rain and snow, reflect this perturbation as well as perturbations caused by temperature changes alone. 

On Mey 17, 1971, the Defense Advanced Research Projects Agency [15] funded our proposal that "temperature variations may be evaluated by measuring stable isotope ratios in natural data banks such as tree rings and varves". L. M. Libby had previously calculated [16] the theoretical temperature coefficients of the stable isotope fractionations in manufacture of wood from C02 and H20, finding that the coefficients are small compared with those measured in rain and snow [17]. 

On these numerical arguments and on the necessity to avoid isotope exchange with liquids, we based our decision to measure stable isotope ratios in whole wood. 

For our first tree sequence [28-32] we measured D/H by reacting sawdust with uranium to produce H2, 99 percent quantitatively. For measurement of 180/160, we modified the method of Rittenberg and Pontecorvo [33] by carrying it out at very high temperatures, 99 percent quantitatively. The temperature must be 525 °C if it is lower, the reaction is not quantitative see the section on our chemistry later in this paper. To measure the stable isotope ratio in carbon, we burned sawdust to completion in oxygen. 

If the stable isotope ratio of 13C/12C is to be further measured in tree rings and interpreted as an indicator of climate variation, (and we have barely begun to initiate its use as a thermometer in the present work, confining our measurements to the stable isotopes in water, because water is so abundant compared to carbon dioxide and because the dependence of its isotope ratios is relatively simple compared with those of carbon dioxide), some more sophisticated considerations must be given to the distribution of carbon dioxide among the reservoirs on the surface of the earth. 

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