NMR is a uniquely qualified method for the quality control of reference standards. Most importantly it is an untargeted method of detection, which means that all compounds containing protons will be detected at the intensity proportional to their concentration in the sample. Proton spectra can be used for both the identification of impurities in reference standards and the quantification of all compounds in a sample. Additionally, because of its linear response, qHNMR does not rely on authentic reference materials. Highly pure compounds can be chosen as calibration standards for quantification purposes. Therefore, the accuracy and precision of analyses becomes independent of the availability of highly pure identifical reference materials.
References (up to 2009; for more recent references, visit qnmr.org):