Verification of reducing sugar with tetrazolium red

Chemicals needed

distilled water

glucose

sodium hydroxide solution 7,5%  C    R 35     S (1/2)-26-37/39-45

2,3,5-Triphenyl tetrazolium chloride

Equipment needed

test tube
burner (preferably alcohol)

Test procedure

• Add a very small spatula-tipful triphenyl tetrazolium chlorid to the test tube and dissolve this with approx. 1 ml water.
• One now adds a small spatula tipful glucose along with 0.5 ml diluted sodium hydroxide and gently warms with the burner.
• Soon a reddish color appears which then quickly becomes deeper and cloudy.

Disposal

• The diluted residues can be discharged into the drainage.

Elucidation

Triphenyl tetrazolium chloride is reduced to a red-colored open chain compound by α-Hydroxyaldehyde, e.g. reducing sugar. Hereby it acts more specifically than Fehling's solution.

Photos

Coloration due to glucose and triphenyl tetrazolium chloride.

Literature

Derived from experiement 61.2, "Red Tetrazolium", [5]