Although NMR is currently regarded primarily as a qualitative tool for molecular structure elucidation, quantitative NMR (qNMR) spectroscopy can be used as an analytical tool by utilizing integration areas of species present in spectra of compound mixtures.  The quantity of an unknown in a mixture can be determined at a per cent level by comparing the relative integration area of the unknown to that of a known amount of standard.  In this experiment, 1H NMR spectroscopy is used to determine the purity of an organic solvent sample, with DMSO as the internal standard, in D2O.  The student is also provided with a pure sample of the unknown for comparison. Nineteen students in a Quantitative Analysis Laboratory analyzed unknown mixtures of methanol, ethanol, isopropanol, and acetone, to which water had been added as an impurity.    Results exhibited random distribution with only two students obtaining errors above 5 per cent.

qNMR analysis of purity of common organic solvents: An undergraduate chemistry laboratory experiment

243rd National Meeting (2012)

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