The use of qNMR spectroscopy for determinations of absolute amount of substance is increasing rapidly. Indeed, qNMR spectroscopy has many advantages for such determinations when compared to more traditional approaches such as chromatographic methods. The National Institute of Standards and Technology is exploring the possibility of developing SRMs for qNMR spectroscopy. The SRMs would be certified for 1H and possibly for other nuclei as well. The need for such SRMs is demonstrated by the fact that SRMs certified for other purposes are currently used as de facto standards. For example, NIST SRM 39 (benzoic acid) is being used as a standard for qNMR spectroscopy, even though it is produced as a calorimetric standard. Such “off-label” use of SRMs for qNMR is undesirable for a multiple reasons. To begin with, the certified purity of these SRMs is typically not the mass fraction purity (the desired quantity for qNMR). Second, instructions for the use of these SRMs for qNMR have not been developed. Third, the spectral properties of these compounds are usually not ideal (e.g., the 1H spectrum of benzoic acid has three multiplets in the center of the aromatic region and one very broad singlet in the organic acid region). For these reasons, we believe that the development of SRMs specifically for qNMR spectroscopy is necessary. The primary requirement for a qNMR standard is a purity that is established with low uncertainty. High purity is also advantageous. The compound must be chemically stable and should not take up water from the air. The compound must have a low vapor pressure. Desirable spectral properties include multiple, narrow, singlet peaks in less populated regions of the spectrum. Of course, low toxicity is always advantageous. This poster will detail our efforts to select suitable compounds to serve as SRMs for 1H qNMR.

Development of standard reference materials (SRMs) for quantitative nuclear magnetic resonance (qNMR) spectroscopy

249th National Meeting (2015)

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