For TTHMs and HAA testing, what is important to note about sample collection?

For testing total trihalomethanes (TTHMs) and haloacetic acids (HAAs), it is critical that samples be dechlorinated before testing. This is essential because chlorine and other disinfectants present in the water can interfere with the analytical methods used to detect and quantify TTHMs and HAAs. If chlorine is not removed from the sample prior to analysis, it can lead to inaccurate results, either by reacting with the compounds of interest or by altering their concentrations.

Dechlorination is usually accomplished through specific methods such as using sodium thiosulfate, which neutralizes chlorine and ensures that the samples accurately reflect the levels of TTHMs and HAAs without any additional interference. This step is a vital part of sample collection and preparation that directly impacts the accuracy and reliability of the analysis.

In contrast, other options may not be as critical in guaranteeing accurate results. For instance, while timely processing of samples is important, the stipulation that samples should not exceed one hour between collection and testing is relevant but not universally mandated as it depends on the specific protocols and conditions. Refrigeration may help stabilize samples, but it is not always a requirement for TTHM and HAA testing. Taking samples during peak hours could provide