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Figure with the word “isotope” and related icons superimposed on a photograph of a man pointing to the figure.
Credit: AdobeStock

Stable and radioactive isotope analysis is an important interdisciplinary tool used by numerous scientists. Therefore, achieving reliable metrology and traceability in isotope analysis is critical for national priorities such as nuclear and homeland security, forensics, medicine and pharmaceuticals, human health and nutrition, and climate science. The NIST Isotope Metrology Program leverages expertise in isotope metrology to provide the measurement science, measurement services (standards), and data science tools required by a diverse user community and critical measurement assurance programs. The impact of this program is demonstrated by scientific breakthroughs to enable the reliable verification and validation of isotope analysis. The goal is to increase cost-effectiveness and savings across the national priorities, improve decision-making including in security/law enforcement and climate science policy, and better target medical treatment to improve human health.


The application of isotope measurements drives advances in an enormous number of fields and stakeholder engagements, including federal and state government agencies, academia, and private industry including the medical industry. The objective of the NIST Isotope Metrology Program is to address the metrology challenges faced by this diverse community and provide the measurement assurances required to support commutability, comparability and validation of isotopic measurements required for confidence in the isotope data results and the usage of these results. By providing a coordinated NIST-wide effort that leverages the broad metrology experience in both the development and delivery of measurement science, measurements services, and data science tools and partnering with our external stakeholders to identify overlaps in the metrology needs of the community we will be able to deliver the metrology tools to our stakeholders more quickly and cost effectively. Using this coordinated partnership approach will allow for advances and breakthroughs across the spectrum of isotope ratio applications leading to, for instance, faster conclusive analysis of forensic evidence that will enable law enforcement to advance investigations more rapidly and give decision makers the confidence in the legal defensibility of findings; more rigorous and exacting drug, food, and flavor provenance/authentication as well as identification of counterfeits; and improved understanding of mass flux in natural systems (e.g. global cycles) to more rigorously guide models used for remediation/mitigation and policy-making.

How can NIST help?

With its mission to support the nation's economy and improve quality of life, NIST is poised to lead by:  

  • Delivering SRMs and RMs as a part of NIST’s measurement services mission.
  • Developing and disseminating advancement tools for breakthrough measurement sciences.
  • Delivering the data science products required for accessibility, rapid analysis, and verification.

NIST Isotope Metrology Webinar Series

The NIST Isotope Metrology Working Group (IMWG) will be kicking off a webinar series featuring NIST’s current capabilities in isotope metrology spanning measurement services, measurement sciences, and data science. The goals of this series are to:

  • Identify existing, on-campus capabilities in isotope metrology and related support services and technologies.

  • Facilitate collaborations and teaming to rapidly address future research opportunities and stakeholder needs.

  • Enhance the visibility of isotope metrology activities at NIST via an outward-facing webpage.

We encourage volunteers to present their work in isotope metrology and other potentially related support areas! Please reach out to any of the team members listed below if you would like your name to be added to the speakers list.

Upcoming Webinar Speakers

All seminars will be held at 2:00 pm (EST) on the date indicated.



Presentation Title

December  2023


Videos and PowerPoint slides from past presentations can be viewed at the Isotope Metrology Webinar Series page. The calendar of scheduled speakers for the year 2024 will be posted soon.

How can I learn more?

This series is being coordinated by the Isotope Metrology Working Group (IMWG), whose mission is to connect NIST staff with other like-minded colleagues and foster collaborations (both internal and external) towards a cohesive and impactful NIST program in isotope metrology that will support the nation’s isotope metrology needs.

If you would like to find out more, please contact any of the following IMWG POCs:

MML: Jacqueline Mann (646.01), Kimberly Harris (646.03), Nik Blonder (646.04), Nathan Mahynski (646.04), Debra Ellisor (646.06), A.J. Fleisher (646.10), Clay Davis (646.11), Evan Groopman (643.05)

PML: Richard Essex (682.04) and Ryan Fitzgerald (682.04)

To be added to the general interest list, send an email to Jacqueline Mann, jacqueline.mann [at] (jacqueline[dot]mann[at]nist[dot]gov). Periodic updates will be sent out via email and posted on this internal website. Additionally, information on current activities can be found at isotope-metrology - NIST - Slack.

Associated Publications

Chemical Sciences Division

  • Christopher SJ, Ellisor DL, Davis WC. Investigating the feasibility of ICP-MS/MS for differentiating NIST salmon reference materials through determination of Sr and S isotope ratios. Talanta. 2021 Aug 15;231:122363. doi: 10.1016/j.talanta.2021.122363. Epub 2021 Mar 31. PMID: 33965029.
  • A. J. Fleisher, “Radiocarbon age is just a number,” Nat. Phys. 17, 1432 (2021). doi:10.1038/s41467-021-01435-5
  • A. J. Fleisher, H. Yi, A. Srivastava, O. L. Polyansky, N. F. Zobov, J. T. Hodges, “Absolute 13C/12C isotope amount ratio for Vienna PeeDee Belemnite from infrared absorption spectroscopy,” Nat. Phys. 17, 889 (2021). doi:10.1038/s41567-021-01226-y
  • D. M. Bailey, G. Zhao, A. J. Fleisher, “Precision spectroscopy of nitrous oxide isotopocules with a cross-dispersed spectrometer and a mid-infrared frequency comb,” Anal. Chem. 92, 13759 (2020). doi:10.1021/acs.analchem.0c01868
  • P. Guay, J. Genest, A. J. Fleisher, “Precision spectroscopy of H13CN using a free-running, all-fiber dual electro-optic frequency comb system,” Opt. Lett. 43, 1407 (2018). doi:10.1364/OL.43.001407
  • A. J. Fleisher, D. A. Long, Q. Liu, L. Gameson, J. T. Hodges, “Optical measurement of radiocarbon below unity fraction modern by linear absorption spectroscopy,” J. Phys. Chem. Lett. 8, 4550 (2017). doi:10.1021/acs.jpclett.7b02105
  • J.L. Mann, Robert D. Vocke, Jr., W.R. Kelly. Determination of Low Level (sub-microgram) Sulfur Concentrations by Isotope Dilution Multi-Collector Inductively Coupled Plasma Mass Spectrometry (ID-MC-ICPMS) Using a 33S Spike and Internal Normalization for Mass Bias Correction. Rapid Commun. Mass Spectrom. (2012), 26, 1175-1180.
  • J.L. Mann and W.R. Kelly. Measurement of the δ34S Value in Methionine by Double Spike Multi-Collector Thermal Ionization Mass Spectrometry Using Carius Tube Digestion. Rapid Commun. Mass Spectrom. (2010), 24, 2673-2679.
  • J. L. Mann, R. D. Vocke, Jr., and W. R. Kelly. Revised δ34S Reference Values for IAEA Sulfur Isotope Reference Materials S-2 and S-3. Rapid Commun. Mass Spectrom. (2009), 8, 1116-1124.
  • J. L. Mann, Christopher A. Shuman, W. Robert Kelly, Karl J. Kreutz. Seasonal δ34S Variations in Two High Elevation Snowpits Measured by 33S-36S Double Spike Thermal Ionization Mass Spectrometry. Geochim. Cosmochim. Acta (2008), 72, 3907-3927.
  • J. L. Mann and W. R. Kelly. Measurement of Sulfur Isotope Composition by Multiple-Collector Thermal Ionization Mass Spectrometry (MC-TIMS) Using a 33S-36S Double Spike. Rapid Commun. Mass Spectrom. (2005), 19, 3429-3441.
  • J. L. Mann, S. E. Long, W. R. Kelly. Direct determination of mercury at picomole/L levels in bottled water by isotope dilution cold-vapor generation inductively coupled plasma mass spectrometry. J. Anal. At. Spectrom., (2003) 18, 1293-1296.
  • J. L. Mann, S. E. Long, C. A. Shuman, W. R. Kelly. Determination of Mercury Content in a Shallow Firn Core from Summit, Greenland by Isotope Dilution Inductively Coupled Plasma Mass Spectrometry. Water, Air, and Soil Pollution (2005), 163, 19-32.
  • S. E. Long, W. C. Davis, R. Day, S. J. Christopher, J. L. Mann, and W. R. Kelly, Improved Certified Values for Total Mercury and speciated Mercury in NIST SRMs Using Isotope Dilution ICP-MS. Am. Lab., (2007), 39, 36-37.
  • W. R. Kelly, R. D. Vocke, J. L. Mann, and G. C. Turk Final report on key comparison CCQM-K35: Determination of sulfur in diesel fuel. Metrologia (2007), 44, 08008 doi:10.1088/0026-1394/44/1A/08008.

Materials Measurement Science Division

  • Groopman E. E., Williamson T. L. and Simons D. S. (2022) Improved uranium particle analysis by SIMS using O3− primary ions. Journal of Analytical Atomic Spectrometry 37, 2089-2102.
  • Szakal C., Simons D. S., Fassett J. D. and Fahey A. J. (2019) Advances in age-dating of individual uranium particles by large geometry secondary ion mass spectrometry. Analyst 144, 4219-4232.
  • Gopon, P., Douglas, J., Meisenkothen, F., Singh, J., London, A., & Moody, M. (2022). Atom Probe Tomography for Isotopic Analysis: Development of the 34S/32S System in Sulfides. Microscopy and Microanalysis, 28(4), 1127-1140. doi:10.1017/S1431927621013568

Radiation Physics Division

Created November 22, 2022, Updated November 15, 2023