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NIST PS1 Primary Standard for quantitative NMR (Benzoic Acid)


The "first-of-its-kind" in an entirely new class of reference material, NIST PS1 Primary Standard for quantitative NMR (Benzoic Acid) is now available! The PS series contains NIST’s first highest-order calibrants for organic chemical measurement that are SI traceable through direct means and suitable for widely applicable qNMR procedures.

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Photograph of NIST PS1 Primary Standard for Quantitative NMR (Benzoic Acid) showing labeled box and two labeled bottles.

NIST Primary Standard (PS) 1.  This reference material is intended for calibration of quantitative NMR to achieve traceability to units of the SI. 

Credit: Lane Sander

With explicit SI linkage, the overall impact of this apical reference material is profound—this primary standard, as well as forthcoming members of its class, provides technology transfer of chemical purity realization to the commercial sector for characterization of many thousands of organic chemical standards. This is a critical—yet often overlooked—component of chemical industry services, as knowledge of chemical purity is an essential first step to achieving accuracy in chemical measurements.

NIST PS1 will be distributed to commercial standard providers, National Metrology Institutes (NMIs), healthcare industries and other federal laboratories via Material Transfer Agreements (MTA) for the validation and certification of routinely used, secondary standards for quantitative NMR (qNMR). These secondary reference materials may be fashioned as industrial products in their own right, providing SI traceability for critical organic chemical measurements in a wide range of sectors (e.g., clinical diagnostics, biomedical research, food labeling and safety), as well as ensuring the quality of products in chemical and biomanufacturing processes. With its inherent design to provide ultimate metrological leverage, the use of NIST PS1 as a qNMR standard supports the delivery of safe and effective products and measurement services important to medicine, the judicial system, and international commerce.


Illustration showing a measurement traceability chain consisting of multiple procedural steps in labeled boxes, starting with results and ending with the SI reference system.
Metrological hierarchy and traceability of chemical measurements supported by NIST primary standards and Standard Reference Materials (in grey). Commercial materials and processes are also illustrated (in blue).
Credit: NIST

NIST PS1 was realized through a cooperative research and development agreement with Sigma-Aldrich Production GmbH via the refinement of an ultra-pure benzoic acid source material, followed by micronization, homogenization and individual unit packaging for long-term storage. A rigorous and metrologically-sound certification of benzoic acid content was conducted by the Chemical Sciences Division that comprised coulometric assays in conjunction with multiple calibration schemes for an internal standard qNMR technique, as well as a thorough analysis of impurities. Collaborative measurements for stable isotope relative abundance determinations and an external standard qNMR technique were also conducted by the National Research Council (NRC) Canada. External standard qNMR comparisons were made to SRM 350b Benzoic Acid (Acidimetric), thereby providing a direct linkage of the historical use of this material as a qNMR standard to NIST PS1 and SI.

This material has been developed for use with statistical tools developed at NIST, including “The NIST Uncertainty Machine” [1] ( and R-based shiny apps currently under development by the NIST Statistical Engineering Division and Chemical Sciences Division for rigorous uncertainty evaluation of chemical measurement procedures [2].

[1] T. Lafarge and A. Possolo (2015) "The NIST Uncertainty Machine", NCSLI Measure Journal of Measurement Science 10(3): 20-27

[2] Toman, B.; Nelson, M.; Lippa, K. (2016) Chemical purity using quantitative 1H-nuclear magnetic resonance: a hierarchical Bayesian approach for traceable calibrations. Metrologia (53): 1192-1203.

Requests for NIST PS1 and Technical Details

Transfer of a single unit of NIST PS1 will be provided without charge, however shipping and handling costs will be incurred by the Recipient.  

Coming Soon: A NIST Special Publication detailing the certification of NIST PS1 Primary Standard for quantitative NMR (Benzoic Acid) is currently in preparation. NIST Special Publications are available at: 

For NIST PS1 technical queries, please contact: michael.nelson [at] (Michael A. Nelson) (click to e-mail) 

For Material Transfer Agreement (MTA) queries, please contact: catherine.rimmer [at] (Kate Rimmer )(click to e-mail) 

Created January 8, 2018, Updated October 20, 2023