How do I test for Vitamin C in a laboratory?

I am teaching in a rural area where the chemical supplies are limited. I have to test for vitamin C. I seem to remember being able to make an indicator of purple cabbage. is this true? Please tell me some simple way (s) to make an indicator for Vitamin C?

How do I test for Vitamin C in a laboratory?
Not cabbage! The SPECIFIC indicator used is 2,6-dichlorophenylindophenol (DCPIP) - a blue/purple dye reduced by ascorbic aid to it's colourless form. There is no suitable substitute that I know of, although red cabbage extract is an excellent GENERAL acid/ base indicator.


Incidently the DCPIP method is useless at determining the Vit C content of blackcurrant juice!
Reply:It is true that you can use red cabbage as an indicator for acid and base. Vitamin C (ascorbic acid) changes the cabbage juice to pink. Using cabbage juice any acids will change it to a range of pink to red. If you are using a base (soap products, detergents, etc) the range is green to blue. Boil the red cabbage in water and let cool down and you have yourself an acid and base indicator. Wonderful experiment!
Reply:I have little experience with testing for vitamin C but this website may help. Good Luck