Why are field duplicates collected during sampling?

• A. To increase the sample volume.
• B. To assess sampling precision and reproducibility of methodologies.
• C. To double-check chain-of-custody.
• D. To expedite data analysis.

Answer: (B)

Field duplicates are collected to measure how consistent the sampling process is and how reproducible the methods are in practice. Environmental samples are inherently variable, so taking two independent samples from the same spot with the same protocol lets you see how much variation comes from the sampling itself rather than real differences in the environment. If the duplicates give similar results, you’ve demonstrated good precision and consistent application of the method. If they differ, it highlights sampling or handling issues that need to be reviewed. This QA/QC check helps quantify sampling error and supports confidence in the data. They aren’t mainly about increasing volume, verifying chain-of-custody, or speeding up analysis.