The limit of detection (LOD) is the smallest amount of analyte that can be distinguished from the background noise. The LOD value corresponds to the concentration at which the analyte signal is three times larger than the standard deviation of the blank signal. Below this value, the analyte signal cannot be differentiated from the background noise. It is calculated by dividing the calibration slope by 3 times the standard deviation of the blank signals.

The LOD indicates the presence or absence of an analyte but is usually too low to be reliably quantified. For quantification, we need another value called the limit of quantification, which is defined as the lowest quantity of analyte that the instrument can quantify. Its value corresponds to the concentration at which the signal is ten times larger than the standard deviation of the blank signal.