What is the maximum elapsed time allowed between obtaining the first and final portions of a composite sample?

The maximum elapsed time allowed between obtaining the first and final portions of a composite sample is set at 15 minutes to ensure the sample's integrity and representativeness. This time frame is crucial because it minimizes the potential for changes in the material being sampled, such as physical, chemical, or biological degradation, that could occur over a longer period. The guideline reflects best practices in sampling protocols, ensuring that all portions collected represent the same conditions and characteristics of the material at that specific time. Ensuring that collection occurs within this window helps to maintain consistency and accuracy in analysis, which is vital for reliable results in any testing scenario.