Table of Contents

Procedure

A. Titration of Vitamin C Standard
1. 25 ml of working starch/iodine reagent was poured into a plastic cup.
2. 4 ml of Vitamin C standard was drawn into a 10 ml syringe.
3. The standard was titrated into the starch iodine reagent drop by drop. The number of drops required to change the reagent colour from blue to clear were counted and recorded. The reagent was gently mixed after the addition of every few drops of standard.
4. Steps 1 to 3 were repeated to ensure precision.
Note: The syringe was rinsed 5 times with distilled water after each use and then rinsed 5 times with the material to be tested before titration was done.
B. Titration of Juices
1. 25 ml of starch/iodine reagent was poured into a plastic cup.
2. 4 ml of juice was drawn into a syringe.
3. The juice was titrated into the starch/iodine reagent. The number of drops required to change the reagent colour from blue to clear were counted and recorded. The reagent was gently mixed after the addition of every few drops of juice.
4. Steps 1 to 3 were repeated to ensure precision. The difference in the number of drops counted for the two tests had to be 2 or less or the testing was repeated a third time.