vitamin C lab report
Measuring the Vitamin C content in a variety of fruit juices
Background Information
Vitamin C, also called ascorbic acid, is a water soluble vitamin. It is a powerful reducing agent that is able to decolourise blue DCPIP (2.6-dichlorophenol indophenols). The decolourisation of DCPIP can therefore be used to calculate the vitamin C content of a variety of fruit juices.
Research Question –
To determine how the content of Vitamin C (%) will differ in fresh fruits (orange, mango, lemon, lime, blackcurrant, pineapple) from that in processed fruit juices (orange, pineapple) by adding drops of the aforementioned fruit juices to DCPIP until the DCPIP gets decolorized.
Variables
Independent Variable – Type of fruit juice used (fresh or processed). NB: the juice from the fruits was freshly squeezed during the experiment.
Dependent Variable – Amount of fruit juice it takes to decolourize the DCPIP in cm3 (±0.2cm3)
Controlled Variables –
1) Concentration of DCPIP was the same in all the samples. A larger amount of it was prepared for this case.
2) The same amount of DCPIP was added in each test-tube (1 cm3) using the same 5cm3 syringe
3) All the fruit juices, fresh and processed, were diluted five times.
4) The same 5cm3 syringe was used to add drops of fruit juices in the test tubes
5) State of decolourization – one sample of decolourised DCPIP was used as a basic one (one with 0.1% ascorbic acid) and later all the fruit juices with DCPIP were compared with the sample. The decolourization should have been the same in both the samples.
6) The other control was similar to (5) above, but instead of having ascorbic acid, it had distilled water. It was used to show that only vitamin C can decolourize DCPIP
Materials
10 Test Tubes
2 x 5cm3 syringes (±0.2cm3) (pipettes were not available so syringes were used)
3 x 20 cm3 beakers
10 cm3 measuring cylinder (±0.1cm3)
DCPIP solution
1.1 % ascorbic acid
Distilled water
Fruit press
Knife
Test tube Rack
Method
1) Label the test tubes,
Background Information
Vitamin C, also called ascorbic acid, is a water soluble vitamin. It is a powerful reducing agent that is able to decolourise blue DCPIP (2.6-dichlorophenol indophenols). The decolourisation of DCPIP can therefore be used to calculate the vitamin C content of a variety of fruit juices.
Research Question –
To determine how the content of Vitamin C (%) will differ in fresh fruits (orange, mango, lemon, lime, blackcurrant, pineapple) from that in processed fruit juices (orange, pineapple) by adding drops of the aforementioned fruit juices to DCPIP until the DCPIP gets decolorized.
Variables
Independent Variable – Type of fruit juice used (fresh or processed). NB: the juice from the fruits was freshly squeezed during the experiment.
Dependent Variable – Amount of fruit juice it takes to decolourize the DCPIP in cm3 (±0.2cm3)
Controlled Variables –
1) Concentration of DCPIP was the same in all the samples. A larger amount of it was prepared for this case.
2) The same amount of DCPIP was added in each test-tube (1 cm3) using the same 5cm3 syringe
3) All the fruit juices, fresh and processed, were diluted five times.
4) The same 5cm3 syringe was used to add drops of fruit juices in the test tubes
5) State of decolourization – one sample of decolourised DCPIP was used as a basic one (one with 0.1% ascorbic acid) and later all the fruit juices with DCPIP were compared with the sample. The decolourization should have been the same in both the samples.
6) The other control was similar to (5) above, but instead of having ascorbic acid, it had distilled water. It was used to show that only vitamin C can decolourize DCPIP
Materials
10 Test Tubes
2 x 5cm3 syringes (±0.2cm3) (pipettes were not available so syringes were used)
3 x 20 cm3 beakers
10 cm3 measuring cylinder (±0.1cm3)
DCPIP solution
1.1 % ascorbic acid
Distilled water
Fruit press
Knife
Test tube Rack
Method
1) Label the test tubes,