Potassium Iodide Solution, Saturated

A saturated solution of potassium iodide in carbon dioxide-free water; it contains some undissolved crystals.

Store protected from light and discard if it fails to comply with the following test.

Add 0.1 mL of starch solution to 0.5 mL of the reagent in 30 mL of a mixture of 3 volumes of glacial acetic acid and 2 volumes of chloroform. If a blue colour is produced it is discharged on the addition of not more than 0.05 mL of 0.1m sodium thiosulfate VS.