In method validation, calibration curves are used to relate instrument response to known concentrations for what purpose?

• A. To adjust the instrument's temperature during runs.
• B. To quantify analytes in unknown samples.
• C. To replace the need for internal standards.
• D. To define the sample collection protocol.

Answer: (B)

Calibration curves establish the link between what the instrument reads (signal) and the known amounts of a substance. In method validation, you generate this relationship using standards with known concentrations, then apply that curve to the signal from unknown samples to estimate how much analyte is present. This is the fundamental way we turn a measured response into a quantitative concentration, and you can also assess how linear and accurate the method is within the validated range.

Other options aren’t the purpose here: calibration curves aren’t about changing the instrument’s temperature, they don’t replace the need for internal standards (which help correct variability and are often used alongside curves), and they don’t dictate how samples are collected.