How long can ammonia samples be held if preserved and refrigerated?

Ammonia samples, when properly preserved and refrigerated, can be held for analysis for up to 28 days. This long holding period is critical when managing sample integrity since ammonia is a parameter that can change quickly in untreated samples due to biological activity, such as nitrification or decomposition processes, which can lead to lower measured concentrations over time.

The preservation methods typically involve adjusting the pH of the samples and cooling them to temperatures that can minimize biological activity. By adhering to these preservation techniques and the specified time limit, analysts can ensure that the ammonia concentration remains stable and representative of the original sample, enabling accurate testing results. This time frame allows laboratories sufficient flexibility in scheduling analyses while ensuring sample integrity is maintained.