How would 2 school girls have tested Vitamin C levels in a drink?

In Ribena, New Zealand 2 school girls expose a large beverage company of falsley claiming one of it's drinks had 4 times the Vitamin C of an orange. They tested the drink and found almost no Vitamin C. Search news for more details.


How would they have done that testing?

How would 2 school girls have tested Vitamin C levels in a drink?
The same way 2 school boys would have
Reply:The process of testing vitamin C in a solution is called titration.


As another answerer stated, this is usually done by the indicator iodine, but with fruit juices, as are the two in question, the iodine is mixed with corn starch. Carbonation is a non-issue, in this case, as both the juices tested contained none.


What happens is:


The corn starch-iodine solution is added in measured amounts to the juice until its color begins to chage. Each measured amount may be given a value of the concentration of vitamin C found/not found in the juice.


How do you "get" the vaue? Easy. At home, in a simple test, one may liquify a store-bought vitamin C pill/tablet/solution in water, add the indicator mixture in small amounts, and use it as a control to gauge the value of vitamin C found in the juices. It is necessary to note here that we are talking drops of indicator added, so small amounts give closer values.





LilD
Reply:ignore jessica, i think she is spreading viruses...





i think it was probably their science teacher
Reply:The only way to test for the presence or absence of a non visible substance is through use of a reagent.





A reagent is a chemical that reacts in a known way to another chemical.





In this case, an iodine solution is the reagent. Adding a liquid containing ascorbic acid (Vitamin C) to an iodine solution will turn the solution from blue to blue green to green and eventually clear.





By testing known quantities of water mixed with known quantities of ascorbic acid to water you can then test to see which quantity best matches the color change observed from the unknown quantity.





When the colors match, we know (roughly) how much Vitamin C was in the mystery liquid.





I'm not at all certain however how carbonation, fructose, or any number of other agents in the beverage would react to the iodine solution.





Without knowing this, there is no way to know if the tests were accurate.
Reply:I'll bet they had help from a grown-up.