Question

If you were given compound X and asked to determine whether it was protein based or carbohydrate based what experiment and controls would you set up to learn the identity of compound X?

Answer 1

To determine whether the given compound X is a protein based or carbohydrate based, there are many confirmatory tests which can give us the results. Down below I have mentioned few of the widely and easily done tests in the laboratory which provide accurate results in just few minutes for the confirmation. Usually control tests are not done as there is no requirement of comparing the results with the control. But if doing control is necessary for your purpose, you can take a know protein sample and know carbohydrate sample check the results alongside the compound X.

you can take any protein and carbohydrate samples that are easily available for you, I have given you examples below.

Protein samples- Whey protein powder, collagen, insulin

Carbohydrates- Starch, potatoes

Test for Proteins:

1. Biuret test – Compound X + Aqueous copper sulfate → Violet colouration confirms the presence of Proteins.
2. Xanthoproteic test – Compound X + Nitric acid → Yellow colour solution confirms the presence of proteins.
3. Millions test – Compound X + Mercuric sulfate in the presence of sodium nitrite and sulfuric acid → Brick red colour solution confirms the presence of proteins.
4. Ninhydrin test – Compound X + Pyridine solution of ninhydrin → Violet colour solution confirms the presence of proteins.

Test for Carbohydrates:

1. Molisch’s test – Compound X + Molisch’s reagent → Purple or violet ring confirms the presence of carbohydrate.
2. Fehling’s test – Compound X + Fehling’s reagent → Red precipitate confirms the presence of carbohydrates
3. Benedict’s test – Compound X + Benedict’s reagent → Red precipitate confirms the presence of carbohydrates.
4. Tollen’s test – Compound X + Tollen’s reagent → Silver mirror confirms the presence of carbohydrates.
5. Iodine test – Compound X+ Iodine solution → Blue colour solution confirms the presence of starch.