Chemical oxygen demand (COD) measurements are used to assess water quality and are frequently used across a range of sectors. The level of water contamination is determined by measuring the amount of oxygen required to oxidise any organic matter found in the sample. It is often used as a measurement of pollutants in water, wastewater and potentially hazardous aqueous wastes.
COD is extensively applied in public wastewater facilities as well as industrial wastewater treatment plants to ascertain the degree of organic contamination in water. It can also give valuable information about the efficiency of the treatment process.
COD analysers are a form of environmental analyser. These provide accurate testing of water, air and soil. They can be used to test for a number of key parameters which may include nitrogen and carbon analysis, dissolved oxygen, trace elements, halogens, chemical contamination and pH.
COD is used as an indirect measure of pollutants found in a water sample, whether waste or natural surface water.
An effective COD analyser will possess several different features.
They may be automated to manage the timing sequence of:
They should be compatible with Laboratory Information Management Systems that support modern lab processes in an intuitive and easy manner. They should also have a stable light source, such as a specific wavelength LED. Effective COD analysers will have a large sample capacity and should be able to confirm clarity prior to reading absorbance.
They will follow published ISO norms for:
They will have easy to run calibrations, run very low/high level COD reagents and work with prefilled Dichromate digestion tubes. They should provide the least amount of waste from analysis, possess a reduced number of interferences and ways to compensate for them.
The EasyPREP COD ticks all the above boxes. It automates the mixing, heating, cooling and analysis of COD samples, simplifying and streamlining the process. COD tubes are placed in a digestion block for sample digestion. This is followed by shaking and cooling. They are then transferred to the spectrophotometer where the samples are analysed. The results and calculations are displayed in real time.
In turbid samples, light scattered from solid particles may interfere with the sample’s measured absorbance. In COD analysis, the presence of turbidity can cause deviations of up to 30% from the real sample value. The The EasyPREP COD offers turbidity detection which overcomes this, allowing the end user to confidently analyse samples knowing that the turbidity level is adequate for analysis.