Chemical oxygen demand (COD)， it is to point to in certain conditions， with strong oxidant treatments in water consumed by the amount of antioxidant， oxygen mg/L Chemical oxygen demand (cod) reflects the water by reducing the Water is organic pollution is very common， thus chemical oxygen demand (cod) as well as the indexes of the relative contents of organic The determination of COD methods are classified into dichromate method and potassium permanganate method at present， pollution monitoring using dichromate method (COD) unified monitoring methods for (hereinafter referred to as the standard method)， its basic principle in strong acid solution， with a certain amount of dichromate in water reducing (will) oxidation， organic matter is mainly the excessive dichromate try to do， use spirit ferrous ammonium sulfate， according to the dosage of the water consumption is reducing the amount of oxygen This has high reliability and repeatability， etcThe standard method to completely， heating， for the timely backflow 2h need the data and large sample， will be determined and the time limit of CODcr rapid determination method is put forward， Fefis its basic principle and method of standard， the method presented in this paper is using sulfuric acid reflux， 250ml use do media devices， reaction temperature and reaction solution acidity， shorten the smell， improve the analysis when backflow through experiment and measurement The standard method， with no significant differences exist， there is no system
