Starch Solution R1

Mix 1 g of soluble starch and a small amount of cold water. Add this mixture, while stirring, to 200 mL of boiling water. Add 0.25 g of salicylic acid and boil for 3 minutes. Immediately remove from the heat and cool.

If long storage is required, the solution shall be stored at 4° to 10°. A fresh starch solution shall be prepared when the end-point of the titration from blue to colourless fails to be sharp. If stored under refrigeration, the starch solution is stable for about 2 to 3 weeks.

Test for sensitivity A mixture of 2mL of starch solution R1, 20 mL of water, about 50 mg of potassium iodide and 0.05 mL of iodine solution R1 is blue.