Abstract
In a study of urines from diabetic dogs, it was noted that boric acid interferes with the determination of glucose by Folin's 1 method. Losses of 7.5% to 13% were found in 2 hour urines to which saturated boric acid solution was added. Other alkaline copper methods also gave low values with glucose solutions containing boric acid as well as with fructose, galactose, maltose and lactose, but not with arabinose. Boric acid does not interfere with the oxidation of glucose by Barfoed's reagent.
The oxidation of glucose, galactose, arabinose and maltose by alkaline iodine solutions is retarded by the presence of borate.
The low specific rotation of glucose in the presence of borax observed by Rimbach and Weber 2 and by Murchhauser 3 is due to the formation of an ester between the borate ion and glucose which decomposes on the addition of a strong acid to give an excess of α glucose. This mutarotates to the normal equilibrium value.
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