What is the maximum hold time for Chemical Oxygen Demand (COD)?

The maximum hold time for Chemical Oxygen Demand (COD) samples is 28 days because COD is a measure of the amount of oxygen required to chemically oxidize organic compounds in water. This analysis can be impacted by factors such as the degradation of organic material over time. To ensure that the sample accurately reflects the water quality at the time of sampling, it is essential to analyze it within 28 days. Beyond this period, the organic compounds may degrade or change chemically, leading to inaccurate results. This timeframe is established by standard methods for the examination of water and wastewater to ensure reliable and consistent testing practices in environmental laboratories.