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

Prof. Imran Khan

Muhammad Naveed Iqbal

Muhammad Naveed Iqbal

Lecturer in Botany. PhD (Plant Sciences) Scholar