Which statement represents a QA/QC practice used in laboratory analysis?

• A. Ignore blanks and standards.
• B. Rely on blanks and standards; duplicate sampling; instrument calibration; replication.
• C. Rely on a single measurement.
• D. Disregard calibration.

Answer: (B)

In lab QA/QC, maintaining data quality comes from using controls and calibration throughout the analytical process. Blanks help detect contamination or carryover in the method by showing what a truly clean sample yields; if a blank shows a signal, you know there’s background interference that must be accounted for. Standards provide known reference values so you can confirm the instrument’s response is accurate and properly calibrated, anchoring measurements to real concentrations or refractive signals. Duplicate sampling checks precision by comparing two independent measurements of the same item, revealing random error and consistency. Instrument calibration ties the instrument’s signal to actual quantities, preventing drift from making results unreliable. Replication—the repeated execution of analyses—tests overall reliability and reproducibility of the results.

Using all these elements together is essential because it detects and controls for contamination, bias, drift, and random error. Ignoring blanks and standards would leave contamination and accuracy unchecked; relying on a single measurement ignores precision and uncertainty; disregarding calibration would render measurements meaningless or inconsistent.