What critical factor must be controlled during a water sampling process to maintain sample integrity?

Maintaining the integrity of a water sample is crucial for accurate analysis and results. One of the most critical factors to control is the sample transportation time. This is important because, over time, changes can occur in the water sample due to various factors such as temperature variations, exposure to light, and biological activity. If the sample is not transported and analyzed within a specified timeframe, it can lead to the degradation of certain substances or the alteration of chemical concentrations, ultimately affecting the test results.

For example, if a sample is delayed in transportation, microbial growth could increase if the water is warm, leading to false readings for parameters such as coliform bacteria levels. Additionally, certain chemical constituents may precipitate or evaporate if left for too long, further skewing the data. Therefore, ensuring that the time between sample collection and analysis is kept to a minimum is essential for preserving the sample's original condition and obtaining reliable test results.

Other factors, such as sample temperature, volume, and color, while still relevant, may not have the same critical impact on the integrity of the sample during transportation as the elapsed time does. Temperature is important for preservation but is secondary to the urgency of timely analysis. Sample volume ensures enough material for testing but won't affect the