Determining and reporting purity of organic molecules: why qNMR

Abstract

Although NMR has been routinely used to determine/estimate relative number of protons for structure elucidation, it has been rarely used to determine and report the purity of organic compounds. Through this paper, we want to emphasize on routine use of quantitative NMR (qNMR) for this purpose. The results of qNMR can be routinely considered as documentation of purity much like other established methods (HPLC, elemental analysis and differential scanning calorimetry). qNMR is a fast, easy, accurate and non-destructive alternate to speed up the whole analytical process and serves the purpose of both identification and purity determination of compounds using single technique.

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“…During data processing, phase and baseline corrections were done manually, and the signals were also integrated manually. The weight of the analyte was calculated from the obtained spectrum as previously described 11) .…”

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“…Major applications of qNMR in pharmaceutical studies are linked to the purity determination of library compounds [3], with most studies targeting the evaluation of impurity levels along with structural information [4], degradation pathways, residual solvent, isomeric composition, and molar ratios [2 •• , 5 • -6] (Figure 2A). …”