Details of Chemical Oxygen Demand Test:
2mL of a water or watse water sample are added to a 16mm glass culture tube containing the digestion reagent and a catalyst. The tube is capped with a polypropylene, PTFE lined cap and heated in a block digester at 150C for 2 hours. The orange Hexavalent chromium is reduced to a greenish trivalent chromium. The analytical range for the spectrophotometric method is 5-150ppm (measured at 420nm).