Testing of Vitamin “C” in a drug

Here is the titration method for testing of Vitamin “C “in a supplement drug. It becomes more difficult to test Vitamin “C” in drug having Other vitamins like Vitamin “A “, Vitamin “E ” Vitamin B”, extracts like Ginkobiloba or Gensing and minerals like Zinc, or Seinite etc. So here is easy method to test the Vit. “C” in that drug.


In the test , 1,2-diphenol-indophenol and metaphosphoric-acetic acid are used. first of all we are going to prepare both of these.

PREPARATION OF 1,2-diphenol-indophenol

Weigh 25mg of 1,2-diphenol-indolphenol in 100ml volumetric flask. add 25 ml of water and mix the weighed quantity. Now weigh 50mg of Sodium by carbonate and add in the mixture. add more 25ml of water and dissolve the reagents by continuous stirring by any mechanical means or  electromagnetic source.  and in last make the volume upto the marks using water.

PREPARATION OF Metaphosphoric Acetic-Acid

In a 100ml volumetric flask, Add 3ml of conc. phosphoric acid and 8ml of glacial acetic acid and makeup the volume upto the mark using distilled water. 


Weigh accurately the product equivalent to 100mg of Vitamin C in 200ml volumetric flask. add 70ml of metaphosphoric acetic-acid in flask and sonicate for 30 minutes. Then makeup the volume upto the mark using distilled water. Mix the solution for 5 minutes and filter through whattman filter paper. or centrifuge some solution. take 4ml of the solution in a 100ml conical flask and add 5ml of metaphosphoric acetic acid. Now titrate with 1,2-diphenol-indophenol until rose pink color . 

each ml of 1,2-diphenol-indophenol used is equivalent to 0.136mg of Vit.C.


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