This standard specifies the method for determining dissolved oxygen in water by iodine titration. This method is a partial modification of the "Winkler method" to avoid certain interferences. Iodometric titration is an established method for quantifying dissolved oxygen. It is possible to measure all samples that do not contain interfering substances, with dissolved oxygen levels ranging from 0.2 mg/l to twice the saturation level (approximately 20 mg/l). Easily oxidized organic substances such as tannins, humic acids, and lignin interfere. Oxidizable sulfur compounds, such as sulfides and thiourea, also react and easily consume oxygen, causing interference. If such substances are present, it is better to measure using the electrochemical probe method specified in JIS K 0400-32-30 (ISO 5814). Nitrite up to 15 mg/l is not a nuisance as it is decomposed by the addition of sodium azide. If oxidizing substances or reducing substances are present, it is necessary to perform the method in 9. If there is a suspended substance that fixes or consumes iodine, the method in Appendix A may be used, but it is even better to measure using the electrochemical probe method.
JIS K 0400-32-10:1999 history
2016JIS K 0102:2016 Testing methods for industrial wastewater
2013JIS K 0102:2013 Testing methods for industrial wastewater
2008JIS K 0102:2008 Testing methods for industrial wastewater
1999JIS K 0400-32-10:1999 Water quality -- Determination of dissolved oxygen -- Iodometric method