Biology – 4.1 Biological molecules | e-Consult
4.1 Biological molecules (1 questions)
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DCPIP (Di-chloro-5-iodophenol) reagent is used to test for the presence of Vitamin C (ascorbic acid). Vitamin C is a reducing agent and can reduce the iodine in DCPIP to iodide ions. The reduction of iodine results in a colour change from yellow to a deep blue-purple colour.
The reaction proceeds because Vitamin C donates electrons to the iodine molecule, causing it to lose its ability to form a coloured complex with starch. The intensity of the blue-purple colour is proportional to the concentration of Vitamin C present. A darker colour indicates a higher concentration of Vitamin C. A weak or absent colour indicates the absence or low concentration of Vitamin C.