When is it recommended to analyze pH samples after collection?

Analyzing pH samples within 15 minutes of collection is recommended because pH can change due to various factors such as gas exchange (e.g., carbon dioxide) and temperature fluctuations. When water is exposed to the atmosphere, it may absorb or release carbon dioxide, which can lead to changes in pH levels. The quicker the analysis occurs, the more accurately it reflects the true condition of the water sample at the time of collection.

Delaying the analysis can result in alterations that may not reflect the original state of the sample, potentially leading to erroneous conclusions about the water quality. This requirement aligns with best practices in water sampling protocols to ensure reliable and reproducible results. Analyzing within a window that is too broad could compromise the integrity of the data.