Stable isotope as tracer

By incorporation of a known percentage of a stable isotope labelled drug (normally deuterium, carbon-13, nitrogen-15, or oxygen-18) the relevant metabolites can readily be detected in a biological isolate, without the need for extensive 

This technique for the location and structural identification of metabolites was demonstrated by studies on nortriptyline and trideuterium labelled nortriptyline the drug, and any metabolites retaining the labelled site, showed a doublet M, M + 3 for the molecular ion and any fragment retaining the label [149]. Although first demonstrated with deuterium, other stable isotopes have been used in this type of work. In deciding on a labelling pattern to be adopted, it must be remembered that the utOity of a M, M + 1 doublet is limited by the effects of the contribution of the natural abundance isotopic species. 

The importance of studying metabolites that occur in very low concentrations in urine has been underlined since the more reactive a species, the lower its concentration may be [143]. Mixtures containing dideuterium-nitrogen-lS-labelled nortriptyline (10) have been used to study urinary and biliary metabol- 

In more recent work along the lines discussed above, new nitrogen containing metabolites of phenoxybenzamine (11) were identified by administration of an equimolar mixture of the drug and the N-labelled drug to rats and dogs. Uri- 

A subsequent technique involved pyrolysis of the metabolites after gas chromatography. The C02 ratio was determined by mass fragmentog- 

A subsequent technique involved pyrolysis of the metabolites after gas chromatography. The C02 C02 ratio was determined by mass fragmentog-raphy. Metabolites in a 24 h urine fraction were detected from administration of doses of C-aspirin of less than 100 ng [155,156]. 

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The use of natural abundance variations in stable isotopes as tracers relies on the fractionations that occur during chemical, physical and biological processes (Ambrose 1993). Differences in fractionation during these processes lead to distinct isotopic signatures for biological materials, such as in foods exploited by humans in antiquity. 

Stable Isotopes as Tracers in Biological, Agricultural, Nutritional and Medical Research... 

Short reviews appeared on the various MS techniques for quantitation of stable isotopes and long-lived radioisotopes and the application of Mg stable isotopes as tracers in biology and medicine. The radioactive isotope Mg is not usually available and has a short half-life (21.3 h), hence its hmited usefulness as a tracer. The sensitivities and interference problems encountered in activation analysis for Al, Mg, Mo, P, Si and Zr were discussed. Much higher sensitivities were found for cyclotron-produced than for reactor-produced fast neutrons or 14 MeV neutrons. ... 

Tritium, Dissolved Ions, and Stable Isotopes as Tracers for Rapid Discharge Along Fractures ... 

Peterson, B. J. (1999). Stable isotopes as tracers of organic matter input and transfer in benthic food webs A review. Acta Oecologica 20(4), 479-487. 

Happen J. D., Chanton J. P., Whiting G. J., and Showers W. J. (1993) Stable isotopes as tracers of methane dynamics in Everglades marshes with and without active populations of methane oxidizing bacteria. J. Geophys. Res. 98, 14771-14782. 

Werner E, Roth P, Heinrichs U, Giussani A, Cantone MC, ZUker TH et al. Internal biokinetic behaviour of molybdenum in humans studied with stable isotopes as tracers. Isotopes Environ Health Stud 2000 36 123-32. 

Advanced isotope quantification is best achieved by NMR spectroscopy using stable isotopes as tracers. Mass spectrometry can afford additional information. As a stand-alone technique, mass spectrometry can be used to determine groups of isotopologues, but it is poorly suited for measuring individual isotopologues in isotopologue mixtures. 

Longstaffe, F.J. (1989) Stable isotopes as tracers in clastic diagenesis. In Mineralogical Association of Canada Short Course in Diagenesis (Ed Hutcheon, I.), pp. 201-277. Mineralogical Association of Canada, Montreal. 

This paper is a continuation of studies on the catalytic reaction of hydrogen with unsaturated compounds using stable isotopes as tracers 1-7). A survey of the literature on the subject and a discussion of the various mechanisms are given in an excellent survey of Bond 8). 

Johnson PE. 1982. A mass spectrometric method for use of stable isotopes as tracers in studies of iron, zinc, and copper absorption in human subjects. J Nutr 112 1414-1424. 

Soltani-Neshan and coworkers from Germany reported the use of sodium bis(trifluoroethyl) dithiocarbamate (FDEDTC) as a chelating agent for the GC-MS analyses of Zn and Cu isotope ratios in fecal samples using stable isotopes as tracers [32]. These authors did not describe the problems with accuracy and the memory effect which were found to be very large in studies reported by Aggarwal et al. [33]. 

Stttrup, S., Hansen, H., and Gammelgaard, B. (2008) Application of enriched stable isotopes as tracers in biological systems a critical review. 

There are many successful applications in literature for the use of stable isotopes as tracers combined with ICP-MS determination for the study of metallomics. In the most common applications, a highly isotopically enriched element used as a tracer is administered to a living organism. Then metallomics studies can be focused on this element, which is detected by ICP-MS. Rodri-guez-Cea et al. used the stable isotope Cd as a tracer for studying the de novo incorporation of cadmium in fish (European eel) liver and kidney.The... 

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