Gasometric Determination of Fermentable Sugar in Blood and Urine

Procedures for fermentative determination, in blood and urine, of glucose, or of sugars resembling it in their fermentability by yeast, have been refined by different investigators during the past few years. The chief source of error, undue prolongation of the time of fermentation to one or more days, was removed by Hiller, Linder, and Van Slyke (1925), who utilized conditions under which glucose could be completely removed from blood in a half hour. Folin and Svedberg (1926), Somogyi (1927, 1928), Benedict (1928), and Raymond and Blanc0 (1928) have utilized these conditions for blood analyses, and Eagle (1926-27) for urine. All the above authors estimated fermentable sugar by the decrease in reducing substances caused by fermentation with yeast. To the technique Somogyi added the improvement of using washed yeast cells, so that correction for reducing substances adherent to the yeast could be obviated. Lund and Wolfe (1926) used a short fermentation period for urine, with a pure culture of yeast, which permitted them to determine with a Barcroft apparatus the COZ formed as a measure of the sugar fermented. By all these authors except Lund and Wolfe the reducing sugars have been estimated by difference, according to the equation: