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About Isotopes

Isotopes are variants of chemical elements: while all isotopes of a given element contain the same number of protons, they vary in the number of neutrons they contain. Variation in neutron number produces chemically identical atoms with different masses, which can be exploited to allow tracing of specific individual atoms through a system.

Stable isotopes

Stable isotopes are generally defined as non-radioactive isotopic elements that do not decay over time. Radioactive isotopes may also be classified as stable isotopes when their half-lives are too long to be measured. These elements can often be found to occur in nature and include isotopes of carbon, nitrogen, hydrogen, oxygen, noble gases and metals. For example, three naturally occurring isotopes of hydrogen include protium (H) having one neutron, deuterium (2H) having two neutrons, and tritium having three neutrons.

Isotopically labeled compounds

Isotopically labelled compounds are compounds that incorporate isotopic elements within their molecular structure and are thus ‘labelled’ by the isotope. These compounds are used to study chemical and biochemical reactions, metabolic pathways or cellular transport. Specifically, isotope-labelled compounds are routinely used for a variety of applications including magnetic resonance imaging (MRI), spectroscopy, nuclear magnetic resonance (NMR), and geochemical analyses. An example of using an isotopic label includes replacing the most common isotope of hydrogen, protium, with deuterium to observe hydrogen exchange reactions in water.

Isotope separation methods

Distillation and Diffusion Processes

Distillation or diffusion are processes which are for enrichment used when there are relatively large mass differences between different isotopes of an element.

Centrifuge enrichment

Centrifuge processes for enrichment includes gas centrifugation and improvements upon the gas centrifuge techniques. This process involves rotating cylinders in order to move the heavier gas molecules containing a given isotope to the outer radius of the cylinder while collecting the lighter gas molecules containing the given isotope in the center of the cylinder.

Electromagnetic enrichment

Electromagnetic isotope separation processes involves first vaporizing the isotope containing molecules followed by ionizing the vapor with positively charged ions. A mass spectrometer, known as the Calutron, is then used to redirect a stream of cations onto a target for collection.

Other methods: laser enrichment, photochemical enrichment and plasma separation

Laser enrichment processes provide for lower energy inputs and thus more economical enrichment. One method currently under investigation is known as the Separation of Isotopes by Laser Excitiation (SILEX). Another laser method that is used to enrich uranium containing the 235U atom is known as molecular laser isotope separation (MLIS) which involves using infrared laser at UF6 molecules and a second laser to free a fluorine atom resulting in precipitation of the remaining UF5 compound out of the gas.

Plasma separation involves the principle of ion cyclotron resonance and uses superconducting magnets to energize a given isotope in plasma consisting of an ionic mixture.



Metabolic studies

Biochemical markers and probes are used to research the uptake of compounds by the body. For example, nutritional studies are commonly performed using isotopic labeled compounds.

Brain and kidney function

Studies of brain and kidney function are performed by tracing isotopes throughout these organs for both diagnostics and treatment applications.


Precursors for therapeutic radioisotopes or radiation therapy are used for a variety of therapies. For example, neuroendocrine tumors are treated by radiotherapy using hormone bound lutetium-177 and yttrium-90.

Clinical pharmacology

Tracing drug metabolism requires the use of isotopes bound to drug in order to understand the processing of the given pharmaceutical by the body.



A wide range of biochemical processes can be studied using stable isotopes. For example, a technique known as stable isotope labeling by amino acids in cell culture (SILAC) is used in proteomics research to help identify disease biomarkers.


The use of isotope labeling allows chemists to study the mechanisms of chemical reactions, as individual atoms can be followed through a system.

Environmental science

Isotopes are valuable for studying release and spread of pollutants in the environment.


The tracing of isotope movement, either within a local system such as an estuary or on a global scale, can allow study of circulation patterns.


Various compounds labeled with nitrogen-15 are used in the study of processes such as plant metabolism and fertilizer uptake.

Isotope Products

Isotopic metals and compounds are available in a variety of forms and enrichment levels. Compounds include stable isotopes containing carbon, nitrogen, deuterium, noble gases, and metals such as oxides, sulfates, carbonates and more. Additionally, we can produce custom syntheses according to customer needs and specifications for research and development.

Recent Research & Development for Isotopes

  • [Determination of mono- to tri-chlorinated dibenzo-p-dioxins and dibenzofurans in stack gas using isotope dilution high resolution gas chromatography-high resolution mass spectrometry]. Tang C, Liu Q, Tian Z, Xie H, Wang M, Liu W. Se Pu. 2014 Sep
  • Nuclear quantum effects and kinetic isotope effects in enzyme reactions. Vardi-Kilshtain A, Nitoker N, Major DT. Arch Biochem Biophys. 2015 Mar 10.
  • [Uncertainty evaluation of the determination of toxic equivalent quantity of polychlorinated dibenzo-p-dioxins and dibenzofurans in soil by isotope dilution high resolution gas chromatography and high resolution mass spectrometry]. Du B, Liu Aimin, Huang Y. Se Pu. 2014 Sep
  • Tracing nitrogenous disinfection by-products after medium pressure UV water treatment by stable isotope labeling and high resolution mass spectrometry. Kolkman A, Martijn AJ, Vughs D, Baken KA, van Wezel A. Environ Sci Technol. 2015 Mar 11.
  • SIMULTANEOUS DETERMINATION OF CREATININE AND CREATINE IN HUMAN SERUM BY DOUBLE-SPIKE ISOTOPE DILUTION LC-MS/MS AND GC-MS. Fernandez-Fernandez M, Rodriguez-Gonzalez P, Añón-Alvarez ME, Rodríguez F, Alvarez Menéndez FV, Alonso JI. Anal Chem. 2015 Mar 9.
  • Solvent and α-Secondary Kinetic Isotope Effects on ?-Glucosidase. Xie M, Byers LD. Biochim Biophys Acta. 2015 Mar 11.
  • Probing the Metabolic Network in Bloodstream-Form Trypanosoma brucei Using Untargeted Metabolomics with Stable Isotope Labelled Glucose. Creek DJ, Mazet M, Achcar F, Anderson J, Kim DH, Kamour R, Morand P, Millerioux Y, Biran M, Kerkhoven EJ, Chokkathukalam A, Weidt SK, Burgess KE, Breitling R, Watson DG, Bringaud F, Barrett MP. PLoS Pathog. 2015 Mar 16
  • A Mn-54 radiotracer study of Mn isotope solid-liquid exchange during reductive transformation of vernadite (δ-MnO2) by aqueous Mn(II). Elzinga EJ, Kustka AB. Environ Sci Technol. 2015 Mar 9.
  • Stable isotope signatures of seasonal precipitation on the Pacific coast of central Panama. Kern Z, Harmon RS, Fórizs I. Isotopes Environ Health Stud. 2015 Mar 11:1-13.
  • Detection of Reactive Metabolites Using Isotope-Labeled Glutathione Trapping and Simultaneous Neutral Loss and Precursor Ion Scanning with Ultra-High-Pressure Liquid Chromatography Triple Quadruple Mass Spectrometry. Huang K, Huang L, van Breemen RB. Anal Chem. 2015 Mar 16.
  • Weaving a two-dimensional fishing net from titanoniobate nanosheets embedded with Fe3O4 nanocrystals for highly efficient capture and isotope labeling of phosphopeptides. Chen X, Li S, Zhang X, Min Q, Zhu JJ. Nanoscale. 2015 Mar 11.
  • Accurate determination of selected pesticides in soya beans by liquid chromatography coupled to isotope dilution mass spectrometry. Huertas Pérez JF, Sejerøe-Olsen B, Fernández Alba AR, Schimmel H, Dabrio M. Talanta. 2015 May
  • Compound-specific isotope analysis of diesel fuels in a forensic investigation. Muhammad SA, Frew RD, Hayman AR. Front Chem. 2015 Feb 27
  • Correction: Quantitative Reconstruction of Weaning Ages in Archaeological Human Populations Using Bone Collagen Nitrogen Isotope Ratios and Approximate Bayesian Computation. PLOS ONE Staff. PLoS One. 2015 Mar 16
  • Nonequilibrium clumped isotope signals in microbial methane. Wang DT, Gruen DS, Lollar BS, Hinrichs KU, Stewart LC, Holden JF, Hristov AN, Pohlman JW, Morrill PL, Könneke M, Delwiche KB, Reeves EP, Sutcliffe CN, Ritter DJ, Seewald JS, McIntosh JC, Hemond HF, Kubo MD, Cardace D, Hoehler TM, Ono S. Science. 2015 Mar 5.
  • Promotion of expression of interferon-stimulated genes in U937 monocytic cells by HIV RNAs, measured using stable isotope labeling with amino acids in cell culture (SILAC). Li Y, Wen B, Chen R, Jiang F, Zhao X, Deng X. Arch Virol. 2015 Mar 15.
  • Abstracts of the 23rd International Isotope Society (UK group) Symposium: synthesis and applications of labelled compounds 2014. Anwar A, Archibald S, Audisio D, Badman G, Bergin J, Bew SP, Bloom J, Bushby N, Busigin A, Chan MY, Davies J, Dilworth J, Dunscombe M, Elmore CS, Engstrom P, Fuchter MJ, Geach NJ, Georgin D, Griffiths A, Hansen P, Hardcastle G, Hiatt-Gipson GD, Hickey MJ, Kitson SL, Lashford A, Lenz E, Lewinton S, Lockley WJ, Loreau O, Maddocks S, Marlière P, McEwen A, Moody TS, Morgan P, Roe SJ, Schenk DJ, Speed DJ, Stockman RA, Sumal K, Taran F, Thurston S, Waring M, Watters WH. J Labelled Comp Radiopharm. 2015 Mar 12.
  • Comparison of measured glomerular filtration rates with isotope infusion and with the modification of diet in renal disease equation in cancer patients with raised serum creatinine. Javaid A, Jaffri SA, Munir I, Qazi MH, Nawaz MK. Saudi J Kidney Dis Transpl. 2015 Mar-Apr
  • Determination of phthalate esters in Chinese spirits using isotope dilution gas chromatography with tandem mass spectrometry. Wang J, Li X, Zhang Q, Xiong J, Li H. J Sep Sci. 2015 Mar 9.
  • Lower radiation burden in state of the art fluoroscopic cystography compared to direct isotope cystography in children. Haid B, Becker T, Koen M, Berger C, Langsteger W, Gruy B, Putz E, Haid S, Oswald J. J Pediatr Urol. 2015 Feb 7.