Science Buddies: "Ask an Expert"

I am testing fruit and vegetable juices for vitamin c content. I made a starch solution with iodine which makes a dark blue color. So this solution to I add drops of fruit juice. The end point is when the blue solution turns clear. The fewer drops required to change the indicator soution clear, the greater the amount of Citamin C in the liquid. When I put a drop of spinach juice in the indiator solution, it turned bright green immediately and I never reached a clear color. I don't know what this means. Can you help me determine how to interpret this result.

For the spinach test you may need to dilute the spinach extract 50% to get a reading. Mix 1 volume spinach extract with 1 volume water to get a reading. If still too concentrated mix one volume spinach extract with 9 volumes of water.

Good luck,

Matthew W. Mulanax