Vitamin C content for food and drink

Question 1

How is vitamin C tested for?

Answer 1

By adding a DCPIP solution. Vitamin D decolorizes blue DCPIP solution.

Question 2

Outline the procedure to find the vitamin C content of different fruit juices.

Answer 2

1. Add vitamin C solution dropwise to 1cm3 of DCPIP solution. Measure the volume of the vitamin C taken to decolorize it.
2. Repeat step 1 twice more and find the mean volume of vitamin C taken.
3. Repeat steps 1 and 2 for each of the fruit juices tested.

Question 3

How is the vitamin C content of unknown fruit juices calculated?

What formula?

Answer 3

Concentration = (concentration of vitamin solution x mean volume of 1% vit C solution) / mean volume of fruit juice

Question 4

What are some sources of error in this practical?

Answer 4

The color change at the end point may be difficult to determine, especially if the fruit juices tested are coloured.