1.14—Core Practical 2 - vitamin C content

To estimate vitamin C in a drink, use a reagent whose colour change is linked to the amount of vitamin C present, then compare the sample with standards or a measured titre. The endpoint must be defined before comparing samples.

Prepare a known vitamin-C standard series, keep reagent volume and sample volume consistent, test an unknown sample, repeat measurements and use the calibration relationship to estimate concentration. Protect vitamin C from unnecessary heat and oxidation.

A darker or later endpoint is only meaningful when the same conditions and endpoint rule were used. Replicates reveal random variation; a blank identifies colour from the drink rather than vitamin C.

If an orange drink decolourises more reagent than the diluted standard, first check dilution and endpoint consistency before concluding that it contains more vitamin C.

The practical estimates vitamin-C-equivalent reducing capacity under the chosen conditions; it does not prove that every antioxidant in the drink or its health effect has been measured.