Which is the best method for obtaining representative samples?

Flow-proportional sampling is considered the best method for obtaining representative samples because it ensures that the samples collected reflect the actual variations in the flow of the material being monitored. In this method, samples are taken in proportion to the flow rate, meaning that during periods of higher flow, more sample volume is collected, while during lower flow, less sample volume is taken. This approach captures fluctuations in concentration and provides a more comprehensive representation of the mixture being analyzed over time.

By adapting the sample collection to the flow conditions, this technique minimizes the risk of bias that can occur if samples are taken during a specific time frame regardless of the flow rate, thereby producing results that reflect the true characteristics of the substance. This kind of sampling is particularly useful in processes where the material properties can change rapidly, allowing for more accurate monitoring and analysis.