Kahepunktilähemine

Kahepunktilähemine, also known as the two-point method or two-point calibration, is a calibration technique used in analytical chemistry and metrology. It involves using two known reference points, or standards, to establish a linear relationship between the measured signal and the concentration or value of the analyte.

The process typically begins with preparing solutions or samples with known concentrations of the substance being measured. These are the two calibration standards. The first standard is usually a blank or a zero concentration sample, which establishes the baseline signal. The second standard is a sample with a known, often higher, concentration of the analyte.

The instrument or measurement device is then exposed to both standards sequentially. The signal generated by the instrument for each standard is recorded. With these two data points (concentration and corresponding signal), a straight line can be drawn. This line, often referred to as the calibration curve, represents the assumed linear relationship between the instrument's signal and the analyte's concentration within the working range.

Once the calibration curve is established, unknown samples can be analyzed. The instrument's signal for an unknown sample is measured, and by locating this signal value on the calibration curve, the corresponding concentration of the analyte in the unknown sample can be determined. Kahepunktilähemine is a widely used method due to its simplicity and effectiveness for many analytical applications, provided that the relationship between the signal and concentration is indeed linear.