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Evaluation of chemical purity using quantitative 1H-nuclear magnetic resonance



Blaza Toman, Michael A. Nelson, Katrice A. Lippa


Chemical purity assessment using quantitative 1H-nuclear magnetic resonance spectroscopy is a method based on ratio references of mass and signal intensity of the analyte species to that of chemical standards of known purity. As such, it is an example of a calculation using a known measurement equation with multiple inputs. Though multiple samples are often analyzed during purity evaluations in order to assess measurement repeatability, the uncertainty evaluation must also account for contributions from inputs to the measurement equation. Furthermore, there may be other uncertainty components inherent in the experimental design, such as independent implementation of multiple calibration standards. As such, the uncertainty evaluation is not purely bottom up (based on the measurement equation) or top down (based on the experimental design), but inherently contains elements of both. This type of uncertainty analysis is readily suitable for an application of Bayesian statistical analysis. In this article we describe this type of analysis in detail and illustrate it using data from an evaluation of chemical purity and its uncertainty for a folic acid material.


chemical purity, uncertainty analysis, observation equation, Bayesian hierarchical model.


Toman, B. , Nelson, M. and Lippa, K. (2016), Evaluation of chemical purity using quantitative 1H-nuclear magnetic resonance, Metrologia, [online], (Accessed July 20, 2024)


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Created September 28, 2016, Updated June 2, 2021