Cov ntsiab lus ntawm Chemical Oxygen Demand Test:
2mL ntawm cov dej los yog watse dej coj mus kuaj yog ntxiv rau 16 hli iav kab lis kev cai raj uas muaj cov zom zom reagent thiab catalyst. Lub raj yog capped nrog ib tug polypropylene, PTFE lined cap thiab rhuab nyob rau hauv lub block digester ntawm 150C rau 2 teev. Cov txiv kab ntxwv Hexavalent chromium raug txo qis rau ib qho ntsuab ntsuab trivalent chromium. Kev ntsuas ntau yam rau txoj kev spectrophotometric yog 5-150ppm ( ntsuas ntawm 420nm).