What is the difference between Quality Assurance and Quality Control in a laboratory?

• A. QA is the overall system ensuring quality; QC is the actual checks (controls, blanks) to verify instrument performance.
• B. QA is the direct measurement of samples; QC is documentation.
• C. QA and QC are the same.
• D. QC governs training programs.

Answer: (A)

In a laboratory, quality is ensured through two linked but distinct functions: QA and QC. Quality Assurance is the umbrella system that defines how quality is built into every step—policies, standard operating procedures, method validation, documentation control, training, equipment maintenance, and audits. It’s about making sure the processes used to generate results are solid and consistently followed.

Quality Control sits inside that system and focuses on the actual checks that confirm performance. It includes running control samples, blanks, calibration checks, and other verifications to monitor instrument accuracy and precision on a day-to-day basis. QC provides the evidence that the measurements being produced are under control and meet predefined criteria. If QC results fall outside acceptable limits, that signals a problem that QA investigates and corrects through actions like recalibration, method verification, or retraining.

So the correct answer reflects QA as the overall system ensuring quality, while QC comprises the concrete checks (controls, blanks, calibrations) used to verify instrument and process performance. The other options mix up roles—for example, direct measurement is a QC activity, not QA, and QA includes more than just documentation and training, while QC is not about governing training programs.