Kalibreerimiskõveral

Kalibreerimiskõveral, known in English as a calibration curve or standard curve, is a fundamental tool in analytical chemistry and various scientific fields. It is a graph used to determine the concentration of a substance, known as an analyte, in an unknown sample. This is achieved by plotting a series of samples with known concentrations (standards) and measuring their corresponding signal response from an instrument.

The process involves preparing a set of solutions with precisely known concentrations of the analyte. These standard solutions are then analyzed using the same instrument and under the same conditions that will be used for the unknown samples. The instrument produces a signal that is directly proportional to the concentration of the analyte. For example, in spectroscopy, the signal might be absorbance or fluorescence intensity, while in chromatography, it could be peak area.

These data points, consisting of known concentrations and their measured signals, are then plotted on a graph, typically with concentration on the x-axis and the instrument signal on the y-axis. A best-fit line or curve is then drawn through these points. This establishes the relationship between the analyte concentration and the instrument's response.

Once the kalibreerimiskõveral is established, an unknown sample containing the analyte is analyzed using the same instrument and conditions. The measured signal from the unknown sample is then located on the y-axis of the calibration curve, and by tracing across to the fitted line and then down to the x-axis, the corresponding concentration of the analyte in the unknown sample can be determined. The accuracy of this method relies heavily on the proper preparation of standards, the stability of the instrument, and the linearity of the response over the concentration range of interest.