Vitamin C Essay Research Paper IntroductionIn this

Vitamin C Essay, Research Paper

Introduction

In this investigation, I will analyse by titration, the vitamin C (ascorbic acid) content of 7 different types of fruit juices purchased from a supermarket. I will test for the presence of vitamin C using an organic indicator solution called DCPIP (dichlorophenol indophenol), which will be reduced to a colourless form from dark blue, at the presence of vitamin C. Reduction is where a molecule losses an oxygen molecule, gains a hydrogen atom or gains electrons. Oxidation is the opposite, i.e. gains an oxygen molecule, loses a hydrogen atom or loses electrons. The amount of juices used to turn the DCPIP colourless will be recorded and the vitamin C content will be determined by measuring the amount of drops of a known vitamin C concentration solution, used to turn the DCPIP colourless.

Vitamin C

Vitamin C plays a vital part in the correct functioning of the living body (most animals synthesise their own vitamin C. we don t). There are 4 ways in which vitamin C considerably benefits the body:

1. Antioxidant. Oxidation of haemoglobin in the blood is necessary to survive, but too much oxidation can be damaging to tissues and organs. Vitamin C prevents too much oxidation from occurring.

2. Homeostasis. When the body is exposed to stress, the adrenal grand uses vitamin C to produce adrenaline in response to the stress by which blood will be moved to the muscles from the digestive system, etc. This is for flight, fright or fight.

3. Collagen. This is the principal component of tendons, ligaments, skin, bone, teeth, and cartilage, in addition to being the ground substance between cells. Inadequate vitamin C levels will lead to weakening of these areas leading to skin lesions, blood vessel fragility, loosening of gums and teeth, characteristics of scurvy.

4. Immune system. Vitamin C is involved in the production of white blood cells, which are the main defence against disease. Without vitamin C, the body will be very susceptible to disease.

Vitamin C has also been linked in the prevention of heart disease and cancer.

List of equipment

Volumetric flask to measure out the correct volume of DCPIP.

Beaker, 1 to containing the juice you wish to test and 1 for the DCPIP solution.

2ml syringe, to measure out the DCPIP.

1ml syringe, to measure out the quantity of juice added to the DCPIP.

10 test tubes, into which the DCPIP and the juice is added.

Test tube rack, to hold the test tubes.

Electronic balance to weight the correct amount of DCPIP.

Method

The experiment was performed at room temperature.

The juices used were:

Orange juice

Grapefruit juice

Lemon juice

Pineapple juice

Mixed fruit juice

Cranberry and raspberry juice

Apple juice

The first task was to measure out 1% DCPIP solution in the volumetric flask and to make sure it is completely mixed (distilled water is used so not to effect the accuracy of the experiment and a squeeze bottle can be used to top up the measurement for further accuracy). The level was read from the bottom of the meniscus. The DCPIP can then be put in to a beaker to ease the filling of the syringes (DCPIP must not be left overnight to avoid oxidation which may affect the results).

2ml of DCPIP are then put into each test tube using the 2ml syringe.

The 1ml syringe is then filled with the 0.05% vitamin C solution and is added drop by drop to each tube individually until the DCPIP has been reduced and the blue colour has disappeared. The amount of 0.05% vitamin C solution needed to reduce the DCPIP is recorded. This procedure was repeated 10 times to provide an adequate level of accuracy to the experiment.

The test was then performed on the fruit juices of unknown vitamin C content.

The relevance of testing the 0.05% vitamin C solution is to determine the vitamin C concentration in the fruit juices by dividing the amount of 0.05% vitamin C solution needed to reduce the DCPIP, by the amount of fruit juice needed to reduce the DCPIP. This is then multiplied by 0.05 (the known concentration of the first solution). By doing this, the vitamin C content of the fruit juices can be determined.

Any difficulties or anomalies were also recorded.

Calculation example:

Volume of 0.05% vitamin C solution needed to reduce DCPIP = 0.39ml

Volume of orange juice needed to reduce DCPIP = 1.55ml

Vitamin C content of orange juice = volume of 0.05% vit. C solution X 0.05%

Volume of orange juice

= 0.39 X 0.05

1.55

= 0.013%

Questionnaire

Put a tick in the box beside the juice that you think has the highest vitamin C content, and a cross in the box beside the juice with the lowest vitamin C content.

Orange juice Apple juice

Lemon juice Pineapple juice

Grapefruit juice mixed fruit juice

Cranberry and raspberry juice

Questionnaire

The questionnaire was given to a sample of 50 people to get an idea on general thoughts on fruit juices vitamin C content.

Juice with the most vitamin C:

52% orange juice

34% lemon juice

10% mixed fruit juice

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