ISO DIS 17289

Description / Abstract: This method is designed for an optical sensor using the technology of fluorescence quenching and signal processing for analysis of dissolved oxygen.

Measurement can be made either as a concentration of oxygen in milligrams per litre, percentage saturation (% dissolved oxygen) or both. The method measures oxygen in water corresponding to 1 % to 100 % saturation. However, most instruments permit measurement of values higher than 100 %, i.e. supersaturation.

NOTE Supersaturation is possible, when the partial pressure of oxygen is higher than in air. Especially in case of strong algae growth supersaturation up to 200 % and more is possible.

The method measures oxygen in water with a saturation higher than 100 %, when special arrangements to prevent the outgassing of oxygen during the handling and measurement of the sample are made. Similarly the transport of oxygen into the sample has to be prohibited, if the saturation is below 100 %.

The method is suitable for measurements made in the field and for continuous monitoring of dissolved oxygen as well as measurements made in the laboratory. It is one of the preferred methods for highly coloured and turbid waters, and also for analysis of waters not suitable for the Winkler titration method because of iron and iodine fixing substances, which may interfere in the iodometric method specified in ISO 5813.

The method is suitable for drinking waters, natural waters, waste waters and saline waters. If used for saline waters such as sea or estuarine waters, a correction for salinity is essential for concentration measurement of oxygen.