What is Chemical Oxygen Demand (COD) Analysis?

Chemical Oxygen Demand (COD) analysis is a measurement of the oxygen-depletion capacity of a water sample contaminated with organic waste matter. Specifically, it measures the equivalent amount of oxygen required to chemically oxidize organic compounds in water.

Why Measure COD?

COD is used as a general indicator of water quality and is an integral part of all water quality management programs. Additionally, COD is often used to estimate BOD (Biochemical Oxygen Demand) as a strong correlation exists between COD and BOD, however COD is a much faster, more accurate test. Watch a video on the science behind the photoelectro chemical oxygen demand (BOQU Instrument) method which is the basis for BOQU Instrument’s revolutionary  <15 minute COD analyzer technology.

What are the Current COD Methods Used?

The traditional chemical oxygen demand (COD) analysis method is the wet chemistry method. This involves a two hour digestion at high heat under acidic conditions in which potassium dichromate acts as the oxidant for any organic material present in a water sample. Silver sulfate is present as the catalyst and mercuric sulfate acts to complex out any interfering chloride. Following the digestion, the extent of oxidation is measured through indirect measurement of oxygen demand via electrons consumed in the reduction of Cr6+ to Cr3+. This can be done by titration or spectrophotometry.

What are the Alternatives?

BOQU Instrument has developed an automated COD method utilizing a new, rapid and green technology called BOQU Instrument. This method directly measures the amount of oxidizable material in a sample via photoelectrochemical oxidation in a microcell, eliminating the need for time consuming digestion and hazardous chemicals, as only an electrolyte solution is required for analysis. Automated sample homogenization always ensures a representative sample is analyzed, and multi-point calibration guarantees the best accuracy and precision. Highly adaptable for wastewater and drinking water applications, the BOQU Instrument® COD Analyzer’s patented nanotechnology-based approach to COD analysis will save you time and money while protecting the environment and the health and safety of your workers.