Stable isotope ratio determination

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). 

Brand W (2002) Mass spectrometer hardware for analyzing stable isotope ratios. In P de Groot (ed.) Handbook of stable isotope analytical techniques. Elsevier, Amsterdam Brandriss ME, O Neil JR, Edlund MB, Stoermer EF (1998) Oxygen isotope fractionation between diatomaceous silica and water. Geochim Cosmochim Acta 62 1119-1125 Bremner JM, Keeney DR (1966) Determination and isotope ratio analysis of different forms of nitrogen in soils. III. Soil Sci Soc Am Proc 30 577-582 Brenninkmeijer CAM (1993) Measurement of the abundance of CO in the atmosphere and the and 0/ 0 ratio of atmospheric CO with applications in New Zealand and Australia. J Geophys Res 98 10595-10614... 

A study of the exchange taking place between Mg pool masses was based on measurement of stable isotope ratios after administration of Mg or Mg doses, and analysis of plasma by ICP-MS . In a study of Mg transport in epithelial cells the isotope ratios were determined by MS for intracellular free Mg(ll) after cell dissolution, as obtained from a feed enriched with Mg, whereas the total free Mg(II) in the cell was determined by a microfluorimetric method using the complex of Mag-fura-2 (34a) with Mg(II) (Section ni.E.4)25. ... 

Radioactive or stable isotopes of noble gases are also used to determine vertical turbulent diffusion in natural water bodies. For instance, the decay of tritium (3H)— either produced by cosmic rays in the atmosphere or introduced into the hydrosphere by anthropogenic sources—causes the natural stable isotope ratio of helium, 3He/ 4He, to increase. Only if water contacts the atmosphere can the helium ratio be set back to its atmospheric equilibrium value. Thus the combined measurement of the 3H-concentration and the 3He/4He ratio yields information on the so-called water age, that is, the time since the analyzed water was last exposed to the atmosphere (Aeschbach-Hertig et al., 1996). The vertical distribution of water age in lakes and oceans allows us to quantify vertical mixing. 

M. W. Todd, J. Glasser, A. A. Kachanov, B. A. Paldus, T. G. Spence, and R. N. Zare, "Stable Isotope Ratios Using Cavity Ring-Down Spectroscopy Determination of, C/I2C for Carbon Dioxide In Human Breath,"... 

Wright, I. P., Boyd, S. R., Franchi, I. A. Pillinger, C. T. 1988 Determination of high precision nitrogen stable isotope ratios at the sub-nanomole level. J. Phys. E 21, 865-875. 

Hiridate, S., Nakadai,T., Shindo, H., and Yoneyama,T. (2004). Carbon source of humic substances in some Japanese volcanic ash soils determined by carbon stable isotope ratio 813C. Geoderma 119,133-141. 

Sulfur, carbon and hydrogen stable isotope ratios of pyrite, kerogens, and bitumens of two high-sulfur Monterey formation samples from the onshore Santa Maria Basin in California were determined. Kerogens from these were pyrolyzed at 300°C for periods of 2, 10 and 100 hours in closed systems and the yields and isotopic compositions of S-containing fractions (residual kerogens, bitumens and hydrogen sulfide) were determined. 

The many chemical reactions and physical processes occurring in the subsurface can also result in substantial alteration of the stable isotopic composition of subsurface waters in sedimentary basins. Because different combinations of these processes can yield similar isotope ratios it is often difficult (Figure 8.10) to unambiguously determine via what pathway a subsurface water has obtained its stable isotope ratio (e.g., Hanor, 1983). 

Lamprecht, G., Pichlmayer, F. and Schmid, E.R. (1994) Determination of the authenticity of vanilla extracts by stable isotope ratio analysis and component analysis by HPLC. Journal of Agricultural and Food Chemistry 42, 1722-1 72 7. 

For example, little is known about the isotopic composition of formaldehyde in the atmosphere. Formaldehyde is a chemical intermediate in hydrocarbon oxidation. The carbon (8 C) and hydrogen (8D) isotopic composition of atmospheric formaldehyde is analyzed using continuous flow gas chromatography isotope ratio mass spectrometry." Isotope ratios were measured using GC-IRMS (Finnigan MAT 253 stable isotope ratio mass spectrometer, single-sector field with electron impact ion source and multiple ion collection) with a precision of 1.1 and 50%(lo ) for 8 C and 8D, respectively. The accuracy of the online continuous flow isotope technique was verified by calibrating three aliquots of the gas phase standard via the offline dual inlet IRMS technique. The concentration of formaldehyde in ambient air was determined on IRMS major ion peak areas (i.e., mass 44 for 8 C and mass 2 for 8D)." ... 

While all the isotopes of carbon follow the same chemical or physical pathway, the rate at which this occurs varies as a function of their difference in mass. The pioneering studies of Harmon Craig in the early 1950s first pointed to the need to consider variations in the stable isotope ratios (13C/12C or of samples if one wished to obtain precise and comparable (or values (78). He determined that the effect of any... 

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