2018/04/27 · COD digestion reagent vials (low range, 3-150 mg/l, and high range 20-1500 mg/l) 2. COD standard solution (HACH COD standard solution of 300 mg/l or 100 mg/l) Procedure: A) Digestion of Sample Sample that contains suspended solids was homogenised by using 100ml of sample for 30 seconds in a blender.