Science & Technology
Tests for Carbohydrates (Preliminary test and Confirmatory test)
Tests For Carbohydrates
Preliminary Tests for Carbohydrates
| Test | Experiment | Observation | Conclusion/Result |
| Heating | Slowly heated some original solution in a test tube. | No precipitate formation | Proteins are absent |
| Iodine Test | 2-3 drops of original solution and then add a few drops of iodine solution. | The solution turns Blue-Black in coloration | Carbohydrates are present |
| Spot Test | Poured one or two drops of original solution with the help of a dropper on a filter paper and allowed it to dry. | No greasy spot appears on the filter paper | Lipids are absent |
Confirmatory Tests for Carbohydrates
| Test | Experiment | Observation | Conclusion/Result |
| Benedict’s Test | 7 drops of original solution + 2-3 ml of Benedict’s solution + gentle heating | Blue color of the solution changes into green, then yellow to orange at last brick red precipitates are formed | Carbohydrates are present |
| Molisch Test | Took 2 ml of O.S. in a test tube. Two drops of the Molisch reagent (a solution of -napthol in 95% ethanol) was added. Then poured slowly into a tube containing two ml of concentrated sulfuric acid so that two layers form. | The formation of a purple product at the interface of the two layers. | Carbohydrates are confirmed |
By Prof. Imran Khan
