| 摘要 |
FIELD: chemistry.SUBSTANCE: invention relates to analytical chemistry and biotechnology and can be used to extract carbohydrates from aqueous solutions for subsequent quantitative determination thereof. The engineering problem of the invention is designing a method of extracting fructose from aqueous solutions using a mixture of ethyl acetate and acetone, which increases extraction of fructose from aqueous solutions without using harmful organic solvents. To solve the engineering problem, the invention provides a method of extracting fructose from aqueous solutions using a mixture of ethyl acetate and acetone, characterised by that a weighed portion of fructose is put into a 100 cmmeasuring flask and, while stirring, filling up to the maximum level with a saturated solution of a salting-out agent in form of ammonium sulphate; a mixture ethyl acetate and acetone, taken in ratio of 4:1 is added to the obtained water-salt solution of fructose, and with volume ratio of the water-salt solution of fructose and the mixture of ethyl acetate and acetone of 15:1, fructose is extracted; after demixing, the aqueous phase system is separated from the organic phase and analysed via ascending thin-layer chromatography, the mobile phase used being the mixture: propyl alcohol - ethyl acetate - water - acetic acid in ratio of 5:5:3:1; the calibration curve of spot area versus fructose concentration is used to find fructose concentration in the aqueous solution; the aqueous phase is once more mixed with ammonium sulphate and fructose is re-extracted using the method given above; the aqueous phase is separated and fructose content therein is determined by ascending thin-layer chromatography; knowing fructose concentration in the aqueous and organic phase, distribution coefficient (D), degree of extraction of fructose after the first extraction (R, %) and degree of extraction of fructose after twofold extraction (R, %) are calculated using the formulae:where cand cdenote fructose concentration in the organic and aqueous phases; f is the ratio of volumes of equilibrium aqueous and organic phases, where Ris the degree of extraction of fructose after the second extraction, %.EFFECT: disclosed method of extracting fructose provides virtually complete extraction of fructose from aqueous solutions without using harmful organic solvents and enables to determine fructose in the concentrate.1 cl, 1 ex |
