Bial's Test

1. Bial’s Test

2. Pentoses vs. Hexoses Pentoses monosaccharide with five carbons in a chain Ex: xylose lyxose arabinose ribose

3. - A test used to detect the presence of pentoses with a test reagent consisting of orcinol, HCl and ferric chloride Bial’s Test

4. Pentoses vs. Hexoses Hexoses simple sugar contgaining 6 carbon atoms galactose glucose fructose

5. Procedure 1 mL Bial’s reagent + 1 mL test solution boil gently until bubbles are observed *Blue green color : +

6. Results Test Test solution Galactose Glucose Fructose Maltose Sucrose Xylose Bial’s orcinol - - - - - + Tauber’s Benzidine - - - - - +

7. Discussion Pentose

8. Hexoses

9. Tauber’s Test

10. Introduction TAUBER’S BENZIDINE TEST → more specific for pentoses → can detect up to 0.01 mg of the pentose either in its free of combined form

11. Procedure 0.5 mL Tauber’s reagent 5 drops of test solution boil over an open flame for 1-2 minutes *formation of cherry red solution : +

12. Results

13. Results Test Test solution Galactose Glucose Fructose Maltose Sucrose Xylose Bial’s orcinol - - - - - + Tauber’s Benzidine - - - - - +

14. Discussion It is more specific for pentoses than the bial’s test because it can detect as little as 0.01 mg of a pentose. The presence of a high concentration of hexoses does not interfere with the test. A positive test is indicated by the formation of a cherry red color.

15. Application When testing for pentose in urine, the urine (0.1 cc.) and benzidine solution (0.5 cc.) is brought to vigorous boiling. The mixture is cooled under tap water and 1 cc. of distilled water is added. In the presence of pentose a pink to red color is shown immediately, whereas if pentose is absent the mixture has a yellowish brown color . Pentu