BIOMOLECULES AND ENZYMES

Detailed explanation-1: -Methods for the detection of vitamin C involve titrating it against a solution of an oxidising agent. There are several oxidising agents that can be used and a commonly used one is 2, 6-dichlorophenol-indophenol or DCPIP. You need to standardise this against a known concentration of vitamin C.

Detailed explanation-2: -Draw up some of the clear liquid into a pipette and then add it, one drop at a time, to a test tube containing a light blue solution of DCPIP. If the extract is acid the colour will change from blue to red. Continue to add more and see if the colour disappears altogether.

Detailed explanation-3: -To your mixture of vitamin C and starch indicator, add drops of iodine, carefully counting the drops, until the solution develops a blue-black colour that does not disappear on stirring. To get a more accurate number you might repeat the experiment and take the average of a number of readings.

Detailed explanation-4: -DCPIP is commonly used as an indicator for Vitamin C. If vitamin C, which is a good reducing agent is present, the blue dye, which turns pink in acid conditions and is reduced to a colourless compound by ascorbic acid.