Determination of urine glucose using O-Toluidine

376 BCHMiss Tahani Al-Shehri

Introduction • Determination of urine glucose is important in

the diagnosis of diabetes mellitus.

Principle • When heated with o-toluidine and glacial

acetic acid, glucose reacts with o-toluidine to form N-glycosylamine. This compound has a blue-green colour and its absorbance can be measured at 625 nm.

O-toluidine

Method 1. Half fill 500 ml beaker with water and put it

on the hot plate to boil. 2. Take three clean test tubes and label them:

TEST, STANDARD and BLANK. 3. Add in each tube 5 ml o-toluidine (from a

burette).

Method Cont.. 4. Then, very accurately, pipette:– 0.1 ml urine into the tube labeled TEST.– 0.1 ml standard glucose solution into the tube

labeled STANDARD.– 0.1 ml distilled water into the tube labeled BLANK.

5. Shake the tubes and put them in the boiling water for 10 minutes. Remove the tubes, cool them

6. Read the optical densities of the TEST and STANDARD against the BLANK.

Calculations Calculations The concentration of glucose in the

standard solution is 100mg/100ml. The concentration of glucose in urine is given

by: O.D. TEST–––––––––––––– 100 = mg Glucose /100ml urine

O.D. STANDARD