Studies on Folin Method of Analysis for Glucose in Normal Urine.

Abstract

Folin stated 1 that acid caused some interfering substance to dissolve from the Lloyd's reagent used in the determination of glucose in normal urine. It seemed that, if acid caused the interfering substance to dissolve, the Lloyd's reagent might first be treated with acid and this substance removed. Accordingly, some of the reagent was treated for some time with concentrated hydrochloric acid. The acid was diluted and filtered off, the Lloyd's reagent was sucked free of liquid, washed thoroughly, dried at 110° C., and powdered in a mortar. The reagent thus treated, while giving lower reducing values than the untreated reagent, still did not allow of quantitative recovery of added glucose. The reagent had changed in color to a greenish tinge, and the acid filtrate contained much iron. It was then treated similarly with concentrated nitric acid, when the color changed to a light gray—almost white. The latter product allowed of quantitative recovery of added glucose, without the use of permutite, and gave values that were somewhat lower than those obtained by the use of the untreated Lloyd's reagent with permutite. Powdering the permutite caused an increase of 5 or 6 mg. % in the reducing value obtained for the urine. If permutite is used, some time can be saved by adding Lloyd's reagent and the permutite together to the diluted urine. There seems to be little change produced in the results by this slight modification.

The average of a number of determinations gave, per 100 cc. of normal urine, 55.4 mg. “glucose”, when untreated Lloyd's reagent and permutite were used, 50.5 mg. when acid treated Lloyd's without permutite was used, 51.5 mg. when acid treated Lloyd's was used with permutite.