Benedict's Test for Reducing Sugars
Aim
To detect the presence of reducing sugars in a given carbohydrate sample and to semi-quantitatively estimate the concentration.
Principle
Benedict's test is based on the reduction of blue cupric ions to red cuprous ions in an alkaline medium.
Sugar + 2Cu2+ + 5OH− → Aldonic Acid + Cu2O↓ + 3H2O
Materials Required
- Benedict's Reagent
- Test Solution (Glucose/Sample)
- Test Tubes & Holder
- Boiling Water Bath
Procedure (Swipe/Click)
Step 01
Take 2ml of Benedict's reagent in a dry test tube.
Step 02
Add 8 drops (0.5ml) of sample into the reagent.
Step 03
Heat in a boiling water bath for exactly 2 minutes.
Step 04
Observe the color change and precipitate amount.
Results
| Final Color | Inference | Approx. % |
|---|---|---|
| Blue (No Change) | Absent | 0% |
| Green | Trace (+) | 0.5% |
| Yellow | Low (++) | 1.0% |
| Orange | Moderate (+++) | 1.5% |
| Brick Red | High (++++) | > 2% |