Soluble starch solution—recently prepared, tested for sensitivity (see Notes, 4). Make a paste with 1 g of natural, soluble
starch (see Notes, 5) and a small amount of cold distilled water. Add, while stirring, to 100 mL of boiling water.
Test for sensitivity—Place 5 mL of starch solution in 100 mL of water and add 0.05 mL of freshly prepared 0.1 M KI solution
and one drop of a 50 ppm chlorine solution made by diluting 1 mL of a commercial 5% sodium hypochlorite (NaOCl)
solution to 1000 mL. The deep blue color produced must be discharged by 0.05 mL of 0.1 N sodium thiosulfate.