METHOD OF DETECTING NON-GRAPE SUGAR IN GRAPE WINE OR WINE MATERIAL

FIELD: chemistry. ^ SUBSTANCE: 25 cm3 of wine or wine material is put into a 50 cm3 flask and the distillate is distilled. 1.5-2.0 cm3 of the distillate is collected. 0.1 N HCl is added to the remaining wet extract until attaining pH equal to 5 and then dried. A portion of this residue in amount of 5-10 mg is used for isotope analysis. The remaining portion is dissolved in 5 cm3 distilled water and 1 cm3 of 1M NaOH and 5 cm3 of 0.5M BaCl2 is added. The insoluble salts formed are precipitated by centrifuging and the supernatant liquid is separately collected. The precipitate which contains acid salts is washed with distilled water to pH of approximately 7 and dried. The supernatant liquid is titrated with 0.1M HCl to pH equal to 7 and dried. Samples of insoluble salts of organic acids and organic substances from the supernatant liquid are used to determine isotope characteristics. 0.1 mg of dry precipitate, 0.1 mg of barium salts of organic acids and 0.1 mg of organic substances which have not reacted with barium 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 ampoules are evacuated to pressure 210-2 mmHg and sealed, put into a metallic container and held in a muffle furnace. After cooling down, the ampoules are broken open in a vacuum installation and the carbon dioxide obtained after combustion is quantitatively collected in hermetic containers for subsequent isotope analysis. The containers are opened in the discharge system of a mass-spectrometer and the analysed carbon dioxide is added in batched manner. During isotope mass-spectrometric analysis, currents arising from the number of ions with m/z 44(12C16O2Çè+), m/z 45(13C16O2Çè+) and m/z 46(12C16O18O) are alternately recorded in mass-spectra of the carbon dioxide sample and the laboratory standard. Characteristics of the isotope composition of carbon dioxide relative the international carbon standard V-PDB is determined in relative units 13C (Ç) using formula (1), included in the software for mass-spectrometer Delta V plus Thermo Finnigan, of the following type: 13C=(Robr/Rst-1)1000(Ç), where Robr=([13C16O2]/[l2O16O2])obr Rst=([l3C16O2]/[12016O2])st, Robr and Rst are ratios of abundance of stable isotopes 13C and 12C in the analysed carbon dioxide, obtained when burning the residue, and the international carbon standard V-PDB, respectively. The obtained ratios of abundance of stable isotopes 13C and 12C of c