Which of the following is a method to measure dissolved oxygen in water?

Dissolved oxygen is a critical parameter in water quality monitoring, as it is vital for aquatic life. The electrochemical method is widely used for measuring dissolved oxygen because it relies on the principle of the electrochemical reaction to provide real-time results. In this method, a probe containing a sensing element is immersed in the water sample, and the amount of current generated correlates directly with the concentration of dissolved oxygen present. This method is favored for its accuracy, sensitivity, and ability to work in various environmental conditions.

Electrochemical sensors, such as polarographic or galvanic cells, can provide continuous data, making them suitable for both laboratory analysis and field measurements. This sensitivity to changes allows operators to make timely and informed decisions regarding water quality management.

Other methods exist for measuring dissolved oxygen, but they may not be as effective in certain situations. For instance, while the Hach method typically refers to a colorimetric technique based on chemical reactions, the gravimetric method is mainly used for measuring solids and not suitable for dissolved gases. Spectrophotometric methods may involve indirect measurements and can require additional sample preparation, making them less practical for continuous monitoring. Therefore, the electrochemical method stands out as a preferred option for directly measuring dissolved oxygen in water