METHOD OF DETECTING NON-GRAPE SUGAR IN 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. 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 2·10^-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(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. Characteristics of the isotope composition of carbon dioxide 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]/[¹²0¹⁶O₂])_st, R_obr and R_st 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 control mixtures consisting of water and sugar of different origins are compared with results of the analysed grape wine or wine material and the origin of sugar therein is determined from the degree of coincidence or deviation.

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

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