Avantor now offers a complete range of COD (Chemical Oxygen Demand) calibration standards (traceable to BAM) as CRM with concentrations between 20 and 10000 mg/L. Can be used to calibrate, control, verify or validate all COD test methods.

• Traceable to BAM
• Supplied with a detailed Certificate of Analysis
• Complete range from 10 to 10000 mg/L
• Customised COD standards available on request
• Shelf life of 24 months / shelf life after opening: 1 month
• Storage at 2 to 8 °C
• Convenient pack size in 100 and 500 ml

COD is defined as the amount of oxygen equivalents consumed in the chemical oxidation of organic matter by strong oxidant (e.g., potassium dichromate) to carbon dioxide.

COD is often used as a measurement of pollutants in water, wastewater, and aqueous hazardous wastes.
The traditional chemical oxygen demand (COD) analysis method is the wet chemistry method. This involves a 2 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 sulphate is present as the catalyst and mercuric sulphate acts to complex out any interfering chloride. Following 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. Colorimetric measurement of COD is faster and easier method to perform than titrimetric analysis and does not require additional reagents.

COD is expressed in mg/L, which indicates the mass of oxygen consumed per litre of solution.

To ensure the lowest possible uncertainty levels COD calibration standards certified values are obtained by a weighted mean of the results of two independent calibration methods: Classical Volumetric and Instrumental (digestion of the chemically bonded organic carbon in the presence of a chemical oxidant and subsequent absorption measurement at 430 nm, using a spectrophotometer).