Determination of 13 C/ 12 C Isotope Ratio in Alcohols of Different Origin by 1 н Nuclei NMR-Spectroscopy

A new express method of indirect assessment of 13C/12C isotope ratio on 1H nuclei is developed to verify the authenticity of ethanol origin in alcohol-water-based fluids and assess the facts of various alcoholic beverages falsification. It is established that in water-based alcohol-containing systems, side satellites for the signals of ethanol methyl and methylene protons in the NMR spectra on 1H nuclei, correspond to the protons associated with 13C nuclei. There is a direct correlation between the intensities of the signals of ethanol methyl and methylene protons’ 1H- NMR and their side satellites, therefore, the data obtained can be used to assess 13C/12C isotope ratio in water-based alcohol-containing systems. The analysis of integrated intensities of main and satellite signals of methyl and methylene protons of ethanol obtained by NMR on 1H nuclei makes it possible to differentiate between ethanol of synthetic and natural origin. Furthermore, the method proposed made it possible to differentiate between wheat and corn ethanol.