Benedict’s test used to indicate the presence of
monosaccharides and reducing sugars. Copper sulphate in the benedict’s reagent
will react with monosaccharides and reducing sugars form brick red precipitate.
Monosaccharides and reducing sugars can react with a benedict’s reagent because
contain free aldehyde or ketone. The positive result is indicated by the color
of the solution changes to green, yellow, orange, or brick red and appears
green, yellow, orange or brick red sediment.
|benedict's test reaction|
Manufacture of reagents benedict:
- Na. citrate 86.5 g
- Na2CO3 50 g
- Distilled water 400 ml
- Dissolve Na. citrate and Na2CO3 into water (assisted by heating), the results are filtered with filter paper and diluted with distilled water up to 425 ml volume.
- CuSO4.5H2O 8.65 g
- Distilled water 50 ml
- Dissolve CuSO4.5H2O into distilled water until dissolved completely.
- Pour the solution B into solution A while stirring slowly, add distilled water up to 500 ml volume.
Material and reagents:
- Benedict’s eagents
- Material to be tested
- Enter 5 ml of benedict’s reagent into the test tube
- Add to 0.5 ml of material to be tested
- Heat in boiling water (water bath) for 5 minutes or over a direct flame for 2 minutes.
- Note the color change and the appearance of a precipitate.