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Tests for Protein (Preliminary Test and Confirmatory Test)

Tests For Protein

Preliminary Tests for Protein

Test Experiment Observation Conclusion/Result

Heating

Slowly heated 2-3 ml of original solution in a test tube. White precipitate formation Proteins 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 color Carbohydrates 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 paper Lipids are absent

Confirmatory Tests for Protein

Test Experiment Observation Conclusion/Result

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 color Proteins 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 appeared Proteins are confirmed

Prof. Imran Khan

About Naveed

Naveed
Lecturer in Botany. PhD (Plant Sciences) Scholar