Science Buddies: "Ask an Expert"

Hello,
I am a class 12 student from Delhi(India). I want to make a project on
"To determine the amount of Vitamin C present in different juices" .
Please tell me how to go about it.


What Have I Done?
I took 10 ml of lemon juice. Added phenolphthalein indicator to it. Titrated it against 0.1 N NaOH solution. This will tell me the amount of acid present in the juice.


Question: Will the other acids present in juice not react with NaOH ?
Are the other acids (e.g. citric acid) present in the juice have
negligible amount ?


If this method is incorrect PLEASE tell me a better method.
kindly help me as soon as possible.


Thank You,
Nishi.

hi nishi!

i guess phenolphthalein indicator used to estimate the acidity of the solution or of the substance and by no means used to measure the presence of vitamin C.

i'm working on the effect of vit c on skin as antioxidant...

julie