Are Organic Citrus Richer in Vitamin C?

After conducting a redox titration experiment for Organic and Non-Organic Grapefruit, I noticed that there was slightly more Vitamin C in the Organic fruit than the Non-Organic. Is this true, that Organic foods have more vitamins than Non-Organic foods because preservatives weaken the soil and restrict the fruit to create a smaller amount of vitamins? The results I received in mL was converted into mg of Vitamin C through a formula, and the Organic grapefruit had 10 more mg than the Non-Organic Grapefruit.Thanks!
- Udaya (age 13)
Portland, Oregon

I honestly do not think so, on the ground that the difference you cited seemed unreasonably large for Vitamin C (aka ascorbic acid) concentration. If you check this website, you will see that the total ascorbic acid content is around 30 mg/100g fruit: http://ndb.nal.usda.gov/ndb/foods/show/2271?fgcd=&manu=&lfacet=&format=&count=&max=35&offset=&sort=&qlookup=09112 . Roughly, this corresponds to 0.3 mg/ml, far less than the difference you are reporting, 10mg/ml. Could there be a unit issue?

Otherwise, I suggest 2 things: every experiment has an inevitable error margin. Try measuring the same grapefruit 3 times and observe how much your results agree. Secondly, try measuring multiple non-organic fruits to see how much deviation there is in a population. My opinion, there could be a real difference, but this could also be affected by how fresh both fruits were.

Tunc

(published on 10/03/2015)