What is the hold time for nitrate-nitrite samples?

The hold time for nitrate-nitrite samples is 28 days. This period is established by regulatory agencies to ensure that samples are analyzed while they still accurately represent the conditions under which they were collected. Nitrate and nitrite can be subject to changes due to microbial activity or chemical transformations, so analyzing them within this specified timeframe is critical for obtaining reliable and valid results. Holding samples longer than 28 days could lead to degradation or changes in concentrations that would render the test results inaccurate or invalid.