What is a calibration curve?

A calibration curve is a graph that illustrates the relationship between the concentration of an analyte in a sample and the corresponding response measured by an analytical instrument, typically expressed as a detector signal. This relationship is critical in analytical chemistry because it allows for the quantification of an unknown concentration based on its measured response.

When a series of known concentrations of an analyte are prepared and analyzed, the resulting instrumental responses can be plotted on a graph. The resultant line often follows a linear pattern, allowing the creation of an equation (usually in the form of y = mx + b) that represents this relationship. By measuring the response of an unknown sample and using the calibration curve, one can determine its concentration accurately.

This process is essential in analytical methodologies such as UV-Vis spectrophotometry, HPLC, and others, where precise quantitative analysis is required. The correctness of the relationship ensures that measurements of unknown samples can be reliably interpreted in terms of concentration, thus establishing the utility of calibration curves in various analytical applications.