What is the definition of the quantitation limit?

• A. The lowest amount that can be quantified with acceptable accuracy and precision.
• B. The smallest amount detectable.
• C. The maximum concentration measurable.
• D. An arbitrary threshold used for screening.

Answer: (A)

Quantitation limit is the smallest amount that can be quantified with acceptable accuracy and precision. It defines the reporting threshold: measurements at or above this limit can be reported as true numeric values with confidence, while smaller amounts may be detectable but not reliably quantified.

This is different from the limit of detection, which is the smallest amount that can be observed above background but not necessarily measured with reliable accuracy. It’s also different from the maximum concentration measurable, which relates to the upper end of the instrument’s linear range. And it isn’t an arbitrary threshold; the quantitation limit is established during method validation based on the method’s performance, including signal-to-noise, calibration, and precision/accuracy requirements.