For testing uniformity of samples, how many grab samples are required?

For testing the uniformity of samples, the standard requirement is typically to acquire three grab samples. This approach allows for a better representation of the overall batch, as it helps account for any variability that might exist within the samples. By taking three samples, analysts can evaluate consistency and detect any anomalies across different parts of the sample.

Using a single grab sample could lead to misleading conclusions, as it might not capture the full spectrum of variations within the larger batch. Similarly, taking only two samples would not provide enough data to assess uniformity adequately, as it still leaves open the possibility that significant variability exists between those two points. Collecting four samples would generally exceed what is necessary for a preliminary assessment of uniformity, complicating the process without substantial benefit.

In summary, three samples strike a balance between sufficient representation of the batch's characteristics and practical data collection efforts, making it the correct choice for testing uniformity.