Water quality -- Determination of the chemical oxygen demand

Document Number: NL ISO 6060 : 2009
Sector: Food Technology
TC: No
ICS: 13.060.50
This international Standard specifies a method for the determination of the chemical oxygen demand, COD, of water. It is applicable to water with a COD value of between 30 mg/l and 700 mg/l. The chloride content must not exceed 1000 mg/l. A water sample which is in accordance with these conditions is used directly for analysis. If the COD value exceeds 700 mg/l, the water sample is diluted. For greatest accuracy it is preferable that the COD value of the sample is in the range of 300 mg/l to 600 mg/l. Under the given reaction conditions, organic compounds are extensively oxidized. Excluded are compounds with certain structural elements (e.g. pyridine nucleus, quaternary nitrogen compounds). Volatile hydrophobic substances may evaporate and thus escape the oxidation. Inorganic compounds being oxidized under the reaction conditions are, for example: — bromide ions, iodide ions; — certain sulfur compounds; — nitrite ions; and — certain metal compounds. On the other hand, certain compounds may react as oxidizing agents under the reaction conditions. Depending on the use of the test results, these circumstances shall be kept in mind. For interferences, particularly from chlorides, see clause 10.