Hallo Misbaudeen. There are two easy ways to estimate ascorbic acid in fruits. Both using titration method. One uses iodine and the other DCPI as reductor. I hope that the following links can help you.

http://www.outreach.canterbury.ac.nz/chemistry/documents/vitaminc_iodine.pdf

http://www.google.com.br/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CDEQFjAA&url=http%3A%2F%2Fseniorchem.com%2FvitaminC_DCPIP.doc&ei=V9o5UsDzDYTi8gTJvIH4BQ&usg=AFQjCNEMiEEBucCjQlZMuCbqEjQDQCmH2w&bvm=bv.52288139,d.dmg

Thank you, Ivan Sestari

the best method is cyclic voltammetry. except this, other methods are susceptible to interferences because they measure the reducing actions of ascorbic acid which other reducing compounds can have. spectrophotometric and HPLC methods are also susceptible. Thanks

Thank you Dr. Azeez

Hello Dr. Azeez, is the cyclic voltammetry available in your Institution?

you can get it in unilag with Prof. Okiei

I am exploring a UV absorbance method for Ascorbic Acid quantification (apparantly the addition of sodium oxalate (or EDTA) can help to minimize any interference effects from metal ions. (I can't comment on its usefulness yet, since I am just starting in this field myself, but I can let you know if I am successful!)

I have found the following articles useful: Selimovic A. Int J Basic and Applied Sciences 2011. 11(02):106-109. Direct Spectrophotometric Determination of L-Ascorbic Acid in Pharmaceutical Preparations using Sodium Oxalate as a Stabilizer.

Salkic M. Argric. Conspec. Sci. 2009. 74(3):263-268. Determination of L-Ascrobic Acid in Pharmaceutical Preparations Using Direct UV Spectrophotometry.

Use Indephenol method. It is a titration method. So it is easy and but not accurate as HPLC. However it is approved by AOAC See attachment

Standard Titrimetric method ia availble for estimation of Vitamin-C