Which method compares an unknown sample to standard samples with known concentrations to determine its concentration?

• A. Calibration Curve
• B. Method Validation
• C. Titration
• D. Chromatography

Answer: (A)

Determining concentration by relating an instrument signal to known standards is done with a calibration curve. You prepare several standard solutions with known concentrations, measure the response for each, and plot response versus concentration. The resulting curve — often a straight line within the linear range — lets you interpolate the unknown sample’s response to read its concentration. This approach provides an accurate, condition-matched reading because the standards and unknown are measured under the same setup.

Titration relies on reacting the analyte with a titrant to a known endpoint and stoichiometry to find concentration, and chromatography uses separation with detector signals that are quantified often via calibration, but the explicit method of reading concentration by a plotted relationship to known standards is the calibration curve method. Method validation is about proving the overall method is reliable, not about determining a specific unknown concentration from standards.