Summary
Isotope fractionation describes fractionation processes that affect the relative abundance of isotopes, a phenomena that occurs (and so advantage is taken of it) in the study geochemistry,[1] biochemistry,[2] food science,[3] and other fields. Normally, the focus is on stable isotopes of the same element. Isotopic fractionation can be measured by isotope analysis, using isotope-ratio mass spectrometry,[1] nuclear magnetic resonance methods (specialised techniques,[2][3]) cavity ring-down spectroscopy,[not verified in body] etc., to measure ratios of isotopes, important tools to understand geochemical and biological systems, past and present.[not verified in body] For example, biochemical processes cause changes in ratios of stable carbon isotopes incorporated into biomass.[not verified in body]
Definition
editStable isotopes partitioning between two substances A and B can be expressed by the use of the isotopic fractionation factor (alpha):
- αA-B = RA/RB
where R is the ratio of the heavy to light isotope (e.g., 2H/1H or 18O/16O). Values for alpha tend to be very close to 1.[1][4]
Types
editThere are four types of isotope fractionation (of which the first two are normally most important): equilibrium fractionation, kinetic fractionation, mass-independent fractionation (or non-mass-dependent fractionation), and transient kinetic isotope fractionation.[citation needed]
Example
editIsotope fractionation occurs during a phase transition, when the ratio of light to heavy isotopes in the involved molecules changes. As Carol Kendall of the USGS states in an information page for the USGS Isotope Tracers Project, "water vapor condenses (an equilibrium process), the heavier water isotopes (18O and 2H) become enriched in the liquid phase while the lighter isotopes (16O and 1H) tend toward the vapor phase".[1]
See also
editReferences
edit- ^ a b c d Kendall, Carol (2004). "Fundamentals of Stable Isotope Geochemistry". Isotope Tracers Project. Menlo Park, CA: USGS. Retrieved April 10, 2014.
- ^ a b Akoka, Serge; Remaud, Gérald (October–December 2020). "NMR-Based Isotopic and Isotopomic Analysis". Progress in Nuclear Magnetic Resonance Spectroscopy. 120–121: 1–24. Bibcode:2020PNMRS.120....1A. doi:10.1016/j.pnmrs.2020.07.001. PMID 33198965. Retrieved 2024-02-11.
- ^ a b Ogrinc, N; Kosir, IJ; Spangenberg, JE & Kidric, J (June 2003). "The Application of NMR and MS Methods for Detection of Adulteration of Wine, Fruit Juices, and Olive Oil. A Review". Anal. Bioanal. Chem. 376 (4): 424–430. doi:10.1007/s00216-003-1804-6. PMID 12819845.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ "Preface to Volume 21". Metals, Microbes, and Minerals - the Biogeochemical Side of Life. 2021. pp. ix–xii. doi:10.1515/9783110589771-003. ISBN 978-3-11-058977-1.
Further reading
edit- Ogrinc, N; Kosir, IJ; Spangenberg, JE & Kidric, J (June 2003). "The Application of NMR and MS Methods for Detection of Adulteration of Wine, Fruit Juices, and Olive Oil. A Review". Anal. Bioanal. Chem. 376 (4): 424–430. doi:10.1007/s00216-003-1804-6. PMID 12819845.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - Faure G., Mensing T.M. (2004), "Isotopes: Principles and Applications", (John Wiley).[full citation needed]
- Hoefs J. (2004), "Stable Isotope Geochemistry", (Springer Verlag).[full citation needed]
- Sharp Z. (2006), "Principles of Stable Isotope Geochemistry", (Prentice Hall).[full citation needed]
- Akoka, Serge; Remaud, Gérald (October–December 2020). "NMR-Based Isotopic and Isotopomic Analysis". Progress in Nuclear Magnetic Resonance Spectroscopy. 120–121: 1–24. Bibcode:2020PNMRS.120....1A. doi:10.1016/j.pnmrs.2020.07.001. PMID 33198965. Retrieved 2024-02-11.