Accurate Determination of Deuterium/Hydrogen Ratios in Natural Organic Compounds through a Nuclear Magnetic Resonance Time-Domain Reference Convolution Method: Application to Ethanol from Three Botanical Sources and Critical Analysis of Systematic Inaccuracies in Previous Methods

The (D/H) ratios of three standard ethanol samples having different botanical origins (cane, grape, and beet) were measured by the official EC method (also known as the Martin method) and compared to the values obtained by a time-domain least-squares procedure, called reference convolution, which takes into account line distortions. It is shown that the official method overestimates the (D/H)II ratio by more than 1%, whereas no statistical difference is detected for the (D/H)I value. A qualitative proof of such a difference is presented. If line distortions are not taken into account, significantly lower (D/H)II values are calculated. Keywords: 2H NMR; ethanol; reference convolution