A method for the determination of small amounts of sugar in urine

Abstract

All human urines probably contain small amounts of sugar, as has quite recently been pointed out by both Cole 1 and Folin, 2 who have described tests for the detection of this small amount of sugar. It has been found possible to determine this reducing substance by precipitating the creatinine and uric acid, and probably other interfering substances with picric acid as suggested by Folin for his qualitative test, and then employing a technique similar to that introduced by Benedict and Lewis 3 for the estimation of the sugar of the blood. 4 It is presumed that the reduring substance in question is glucose, although this has been found difficult of positive proof. This question is being further investigated.

The method is carried out as follows: About 2 grams of dry picric acid are added to 10 c.c. of urine in a test tube and the tube vigorously shaken. The tube is now stoppered and placed in an ice box at 0° C. After the tube has stood for an hour, it is again shaken and then allowed to stand over night in the ice box, after which the mixture is filtered through a small filter paper into a dry test tube. The filtrate now contains less than 0.1 mg. of creatinine per c.c, a quantity too small to invalidate the estimation of the sugar. If the urine has reacted negatively to Benedict's qualitative reagent, the filtrate is diluted 1-5 or 1-10 with saturated picric acid solution. If the qualitative test has shown a small amount of sugar, a greater dilution is made. The following rule may be followed: for 0.1 per cent. of sugar dilute 1-5, for 0.2 per cent. dilute 1-10, for 0.3 per cent. dilute 1-15, etc.