METHOD OF DETERMINING ORIGIN OF ETHANOL IN NATURAL GRAPE WINE OR WINE MATERIAL Russian patent published in 2011 - IPC G01N33/14 

FIELD: chemistry.

SUBSTANCE: 25 cm³ of wine or wine material is put into a 50 cm³ flask and the distillate is distilled off. 1.5-2.0 cm³ of the distillate is collected. A first portion is thrown away in amount of 0.2 cm³. The wet residue remaining after distilling off the distillate is dried until complete removal of water. An aliquot of the obtained dry residue in amount of 5-10 mg and an aliquot of the distilled off distillate (about 5 mcl) are separately put into ampoules made from refractory pyrex glass and sealed at one end, into which 0.5 g of oxidised copper oxide is put. The copper oxide is pre-annealed in a muffle furnace. The distillate in the ampoule is frozen at liquid nitrogen temperature (-196°C). The ampoules are evacuated to pressure 2·10^-2 mm Hg and sealed. The ampoules are then put into metal containers and held in the muffle furnace at temperature 560°C for 24 hours. After cooling down, the ampoules are broken open in a vacuum installation and the carbon dioxide obtained after ethanol oxidation is quantitatively collected in a hermetic container for subsequent isotope analysis. Containers with carbon dioxide gas are opened in the discharge system of a mass-spectrometer and the analysed carbon dioxide is added in a batched manner. During isotope mass-spectrometric analysis, currents arising from the number of ions with m/z 44(¹²C¹⁶O₂ ⁺), m/z 45(¹³C¹⁶O₂ ⁺) and m/z 46(¹²C¹⁶O¹⁸O) are alternately recorded in mass-spectra of the carbon dioxide sample and the laboratory standard. The working gas used is gaseous carbon dioxide. Characteristics of the isotope composition of the carbon of the carbon dioxide, obtained during combustion of the distillate and dried residue relative the international carbon standard V-PDB is determined in relative units δ¹³C (‰) using formula (1), included in the software for mass-spectrometer Delta V plus Thermo Finnigan, of the following type: δ¹³C=(R_obr/R_st-1)1000(‰), where R_obr=([¹³C¹⁶O₂]/[^l2O¹⁶O₂])_obr R_st=([^l3C¹⁶O₂]_st, R_obr and R_st are ratios of abundance of stable isotopes ¹³C and ¹²C in the analysed carbon dioxide, obtained from combustion of the distillate or dry residue, and the standard. Isotope characteristics of carbon (δ¹³C,‰) of all control samples of ethanol of different origins must be predefined. The obtained ratios of abundance of stable isotopes ¹³C and ¹²C of control mixtures consisting of water and ethyl alcohol of different origins are compared with results of the analysed grape wine and the origin of ethanol and naturalness of the wine or wine material is determined from the degree of coincidence or deviation. The difference in values of quantitative carbon isotope characteristics of ethanol and dry residue of over 0.5‰, as well as that between the control and analysed sample of over 1‰, indicates that the ethanol does not originate from grape.

EFFECT: disclosed method increases accuracy and reliability by 90%.

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