The HI76408W is a slim Clark-type polarographic dissolved oxygen probe for Hanna’s benchtop and portable dissolved oxygen meters designed to be used to perform a biochemical oxygen demand (BOD) test. With a longer probe shaft and integrated stopper, this probe is designed to fit directly into a B.O.D. bottle and left for the incubation period of 5 days. The probe is constructed of durable ABS plastic and contains an integrated temperature sensor for temperature compensated measurements.
The membrane separates the probe’s platinum cathode and silver anode from the water sample being tested but allows oxygen to enter. Oxygen diffuses across the membrane and interacts with the polarographic system to produce a current proportional to the dissolved oxygen concentration.
In natural waterways, dissolved oxygen is both produced and consumed. The levels of dissolved oxygen can fluctuate over time based on season, temperature, and/or altitude. Oxygen is produced from photosynthesis by aquatic plants and from atmospheric diffusion. Oxygen is consumed by decomposition, natural chemical reactions, and aquatic animals. It is common for wastewater treatment plants to utilize microorganisms for the decomposition of organic materials. The amount of oxygen needed by these organisms is defined as the biochemical oxygen demand or BOD. The test for biochemical oxygen demand (BOD) is a bioassay procedure that measures the amount of oxygen consumed by bacteria while they decompose organic matter under aerobic conditions at a specified temperature. Procedures used to determine DO concentration are described in the National Field Manual 6.2.