critical value symbol: $L_{c}$

Synonyms: critical level, decision level
https://doi.org/10.1351/goldbook.08017
Measured quantity value for a quantity of a component in a material, above which the component is declared to be present.
Notes:
  1. The critical value is usually considered to be a characteristic of a particular measurement procedure performed in a particular laboratory.
  2. In some European legislations, the term "decision limit" (denoted as CCα) is used for the concept 'critical value'.
  3. The quantity measured is usually a mass fraction or a concentration but can also be, for example, a mass or an amount of substance.
  4. The critical value is chosen to give a probability α (usually 0.05) of a measured quantity value exceeding the critical value when the component is absent.
  5. The detection decision is made by comparing a measured quantity value with the critical value.
  6. Another important concept in characterizing the capability of detection of measurement procedures is the limit of detection.
Source:
PAC, 2021, 93, 997. 'Metrological and quality concepts in analytical chemistry (IUPAC Recommendations 2021)' on page 1005 (https://doi.org/10.1515/pac-2019-0819)