Which statement best describes the purpose of a standard curve in quantitative testing?

• A. It enables interpolation of unknown results by relating signal to known concentrations.
• B. It replaces the need for any controls.
• C. It determines the retention time of chromatography.
• D. It is only used for visual inspection.

Answer: (A)

The purpose of a standard curve is to translate the detector signal into a specific concentration by relating known standards to their responses. You prepare standards with known concentrations, measure their signals, and plot signal versus concentration to create a curve. Then you measure the signal from an unknown sample and interpolate its concentration from that curve. This allows you to account for how the assay reagents and instrument respond across the measurement range and provide a quantitative value for the unknown within the curve’s reliable range. It isn’t about replacing controls, determining chromatography retention time, or relying on visual inspection alone.