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Analytical Chemistry & Spectroscopy

Calibration Curve

A plot of instrument response against known analyte concentration, used to determine unknowns.

Formula / equation y = mx + c
Unit Various

In depth

Standards spanning the expected concentration range are measured, the best straight line is fitted by least squares, and unknown concentrations are read from it. The unknown should fall inside the calibrated range, since extrapolation beyond the linear region is unreliable.

Examples in the real world

Plotting absorbance against concentration for a series of copper standards before measuring an unknown.