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tests for protein

Tests for Protein (Preliminary Test and Confirmatory Test)

Tests For Protein

Preliminary Tests for Protein



Slowly heated 2-3 ml of original solution in a test tube.White precipitate formationProteins are present.

Iodine Test

Took 2-3 drops of original solution and then add a few drops of iodine solution.The solution did not turns its colorCarbohydrates are absent

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 appeared on the filter paperLipids are absent

Confirmatory Tests for Protein


Million’s Test

i)   Took 2-3 ml of original solution and add 7-9 drops of Million’s reagent.


ii) Prepared the same mixture and boiled

Formation of white precipitates


Appearance of brick red color

Proteins are present


Proteins are present

Ninhydrin Test


5 ml O.S. + 3 drops of 1% solution of ninhydrin in ethanol is added to 1 ml of the solution and the solution heated for five minutes in a boiling water bath.formation of red, blue or purple colorProteins are present

Biuret Test

2.5 ml original solution and add 2.5 ml of 5% of NaOH solution. Then mixed it by shaking thoroughly, and added 1-2 drops of 1 % copper sulphate solution and shake well.Violet, red or pink color appearedProteins are confirmed

Prof. Imran Khan

About Muhammad Naveed Iqbal

Muhammad Naveed Iqbal
Lecturer in Botany.PhD (Plant Sciences) Scholar

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