Oh, Say Can You See the Vitamin C?

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Author: Nancy Rogers Bosse


Vitamin C is important to health. It helps prevent scurvy. It also helps the body heal itself. In this investigation, three different juices are tested to determine which juice contains the greatest amount of vitamin C. The juice that requires the least amount of drops contains the greatest amount of vitamin C.


  • Bowl
  • ½ cup water
  • 1 tablespoon cornstarch
  • Spoon
  • 4 drops 2% iodine (purchased at a pharmacy)
  • 3 clear glasses
  • 3 different types of juices (including one that is fortified with vitamin C)
  • medicine dropper

Experimental Procedure:

  1. Gather the necessary materials.
  2. Mix the cornstarch with water until dissolved.
  3. Using a medicine dropper, add iodine to the cornstarch mixture. Add one drop at a time until the mixture turns dark blue. Rinse the dropper.
  4. Place 1/3 of the mixture into each glass.  
  5. Use the clean medicine dropper to gather a sample of one of the juices. Place one drop of juice into the mixture of the first glass and stir. Continue adding and stirring the juice one drop at a time until the dark blue color disappears. Record the number of drops of juice.
  6. Repeat Step 5 for the other two juices. 


When iodine is mixed with starch, it turns a deep blue color. When vitamin C is present the deep blue color fades.


“Vitamins” at 

“Facts about Vitamin C” by Linda B. Bobroff and Isabel Valentine-Oquendo at 

“The Antioxidant Vitamin – Vitamin C” by Gary Null, Ph.D at 

“The Benefits of Vitamin C” by Kathleen M Zelman, MPH at


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