2gm sample was mixed with 5ml of 20 % metaphosphoric acid solution and filtered through whatman no.1. The filtrate (1ml) was put in a small beaker and mixed with 10 ml distilled water. After that, 2 ml was transferred into a beaker, shaken with 2 drops of phenolphthalein solution and titrated against 2, 6– indophenol until pink color was developed.Vitamin C content was calculated according to the following equation:

Vitamin C (mg/g)= (Dye factor*titre value* volume made up)/ (aliquot taken*sample weight)

Abu Saeid, thank you for your answer but I want to determine vit-C by using HPLC. Regarding that method, I have to make m-phosphoric acid in glacial acetic acid solution. I want to know the protocol to make this solution.

I thought it was 10% w/w (its been a long time).

Thank you for your clarification @Bruce Neagle