What should be done when collecting effluent samples to ensure their integrity?

When collecting effluent samples, maintaining their integrity is crucial for accurate analysis and results. Each of the listed practices contributes to this goal, making them collectively essential.

Labeling samples with the date ensures that there is a record of when the sample was taken. This information is vital for understanding the context of the data and for correlating it with treatment processes or environmental conditions at that time.

Using appropriate storage containers is equally important, as different containers can affect the chemical composition of the sample. Containers made of specific materials prevent contamination, preserve the sample's characteristics, and ensure compatibility with the tests that will be performed.

Following chain of custody procedures is a critical practice for preserving the integrity of the sample during the entire process from collection to analysis. This involves tracking who handled the sample, when, and under what conditions, which helps prevent tampering and ensures the reliability of the results.

By implementing all these measures, the integrity of the effluent samples is upheld, thereby ensuring that the analyses conducted are valid and reflect true environmental conditions. Thus, the selection of "All of the above" is justified as each component plays an integral role in preserving sample integrity.