16.1 This test method is applicable to waters containing dissolved oxygen in the range from 50 to 20 000 μg/L. It is the user's responsibility to ensure the validity of this test method for waters of untested matrices.

16.2 This test method describes procedures that utilize electrochemical probes for the determination of dissolved oxygen in fresh water and in brackish and marine waters that may contain dissolved or suspended solids. Samples can be analyzed in situ in bodies of water or in streams, or samples can be collected and analyzed subsequent to collection. The electrochemical probe method is especially useful in the monitoring of water systems in which it is desired to obtain a continuous record of the dissolved oxygen content.

16.2.1 This test method is recommended for measuring dissolved oxygen in waters containing materials that interfere with the chemical methods, such as sulfite, thiosulfate, polythionate, mercaptans, oxidizing metal ions, hypochlorite, and organic substances readily hydrolyzable in alkaline solutions.

16.3 Electrochemical dissolved oxygen probes are practical for the continuous monitoring of dissolved oxygen content in natural waters, process streams, biological processes, etc., when the probe output is conditioned by a suitably stable electronic circuit and recorded. The probe must be standardized before use on samples free of interfering materials, preferably with the azide modification of Test Method A.

26.1 This test method is applicable to waters containing dissolved oxygen in the range from 50 to 20 000 g/L. It is the user’s responsibility to ensure the validity of this test method for waters of untested matrices.

26.2 This method is for an instrumental probe-luminescence-based sensor using the technology of frequency-domain lifetime-based luminescence quenching and signal processing for analysis of dissolved oxygen. This method is amenable to all water and wastewater matrices that are free from interferences at normal water and influent-to-treatment and final effluent wastewater concentrations.

26.3 Sustained periods of sensor immersion in water containing high levels of chlorine dioxide may degrade sensor performance. Refer to manufacturer’s guidelines for specific instrument interferences.

26.4 Intrumental probeluminescence-based sensors for dissolved oxygen are practical for the continuous monitoring of dissolved oxygen content in natural water, process streams and biological processes, etc.