| 摘要 |
FIELD: analytical methods. SUBSTANCE: invention relates to standardizing of pectins and alginates used as heavy metal detoxicants. Aqueous solution of polysaccharides is titrated potentiometrically or conductometrically with 0.1 M sodium hydroxide solution (determining free carboxyl groups). To titrate polysaccharide solution, 0.1 M sodium hydroxide solution is poured and resulting solution is allowed to stand during 24 h at room temperature until hydrolysis of ester groups is completed, after which solution is titrated with 0.1 M hydrochloric acid solution. More 0.1 M hydrochloric acid solution is then poured and resulting solution is heated for 10 min on boiling water bath, cooled, and filtered. Polyuronic acid precipitate is washed on filter with water until negative acid test of wash water is attained, after which precipitate is quantitatively transferred into beaker with the aid of 0.1 M sodium hydroxide solution and dissolved during 30 min with periodic stirring. Finely, solution is titrated with 0.1 M hydrochloric acid solution. Reference experiment is simultaneously performed. EFFECT: increased accuracy and information content. 11 tbl, 4 ex |
