Comparative study on ozone oxidation chemiluminescence method and classical alkaline potassium permanganate method for determination of chemical oxygen demand in seawater

Seawater in the coastal waters of Qingdao, China was collected, and COD was measured by ozone oxidation chemiluminescence method and alkaline potassium permanganate method which was adopted in China as the standard method for measuring COD in seawater, respectively. The results show that when COD was less than 1 mg/L, the absolute error of ozone oxidation chemiluminescence method was less than 0.1 mg/L, and when COD was more than 1 mg/L, the relative error was less than 10%. The relative standard deviation of ozone oxidation chemiluminescence method was lower than 5%, and the detection limit was 0.0022 mg/L. The results of ozone oxidation chemiluminescence method were close to those of alkaline potassium permanganate method. With higher precision, lower detection limit, faster measurement, and online measurement, ozone oxidation chemiluminescence method is an ideal monitoring method for COD in seawater in the field.