With this parameter the total oxygen demand of water can be measured. Even in the 1970s online analysers for the determination of TOD were available. After the rise in popularity of the COD-dichromate method the TOD had been suppressed in many countries as the COD prevailed in analysis of waste water. However, the total oxygen demand is a reliable and reproducable parameter to indicate the oxygen demand of water. In the United States it is standardized with the ASTM D6238 and very commonly used.
The TOD correlates easily to the COD. Hence, this parameter is a preferable alternative to the COD measurement. Moreover, it is very suitable for online measurements, especially with the thermal combustion method at 1200°C.