To determine the presence or absence of vitamin C in a beverage sample, we can use iodometric titration in the laboratory.

there are practical ways you can try yourself at home, using the materials that you use everyday.
The test I mean is a qualitative test that is just knowing the presence or absence of vitamin C in the drink, while how many vitamin C contained I do not count.

Necessary materials :

1. 5 tablespoons orange drink samples
2. 1/2 glass of water
3. Starch solution
4. Betadine antiseptic
5. 1 spoon of cornmeal / cornstarch

Ways of working :

1. Make a starch solution: dissolve cornstarch / corn / tapioca in 1/4 cup water, stir quickly until all the flour is soluble. 2. Prepare a sample of orange drink in a glass, add 1/2 cup water of water, stir 3. Take 1 tablespoon kanji solution, pour in the sample 4. Drop the betadine septic 2 drops and stir, continue until the sample solution is blackish black. 5. Stop the droplets if the color of the solution is already blackish (the blackish color indicates in the sample contained vitamin c) 6. Write how many drops of betadine are needed to make a sample of yellow to blackish.

From 3 experiments that have been done:

Glass 1: 5 tablespoons orange juice dissolved in half a glass of water (it takes 98 drops of betadine)

Glass 2: 6 tablespoons orange juice dissolved in half a glass of water (it takes 45 drops of betadine)

Glasd 3: 7 tablespoons orange juice dissolved in half a glass of water (it takes 25 drops of betadine).

Conclusion:

The more vitamin C contained in the sample the more betadine we drop to make the color of the solution from yellow to blue-black.

Look for the facts:

1. Try another experiment using different samples, such as orange drink in a glass of plastic that is sold freely on the market that is said to contain vitamin C

2. Test vitamin C tablets, by grinding vitamin C into powder and dissolved in 1/4 glass of water. you should use vitamin C tablet only, do not tablet multivitamin.

Little extra about vitamin C:

Vitamin C is used to protect the body from viruses, germs, and germs. Vitamin C in the body works as a shield from germ attacks. Vitamin C that we drink will coat the entire body cells, if there are germs in, then the germs will attack on vitamin C, not our body. Vitamin C acts as an antioxidant.

Source :
What is Vitamin C
Clinical data of vitamin c