CPAC2 - Vitamin C content

• Describe how to measure vitamin C content of orange juice

  DV = Vol of Vitamin C required to decolourise DCPIP

  CV = Vol of DCPIP (1cm3) , conc of DCPIP(1%), temp (water bath)

  BTW

  DCPIP reduced, blue-> colourless

  Method:

  • 1cm3 of 1% DCPIP in test tube
  • Add vitamin C (unknown conc) in burette, read initial vol
  • Add drop by drop into DCPIP
  • Shake tube at regular intervals e.g. 10 mins, to incorporate Vitamin C
  • Record vol when DCPIP decolourises
  • Calulcate change in vol of vitamin C
  • Repeat 2 more times, mean vol to decolourise DCPIP
  • Repeat this whole thing 3 times with Vitamin C standard solution (known conc) + calculate mean
  • To quantify results of titration
  • Plot results on calibration curve
  • To find conc of Vitamin C