ISO 11843-5:2008 is concerned with calibration functions that are either linear or non-linear. It specifies basic methods to construct a precision profile for the response variable, namely a description of the standard deviation or coefficient of variation of the response variable as a function of the net state variable, transform this precision profile into a precision profile for the net state variable in conjunction with the calibration function, and use the latter precision profile to estimate the critical value and minimum detectable value of the net state variable.
The methods described ISO 11843-5:2008 are useful for checking the detection of a certain substance by various types of measurement equipment to which ISO 11843-2 cannot be applied. Included are assays of persistent organic pollutants (POPs) in the environment, such as dioxins, pesticides and hormone-like chemicals, by competitive ELISA (enzyme-linked immunosorbent assay), and tests of bacterial endotoxins that induce hyperthermia in humans.
The definition and applicability of the critical value and minimum detectable value of the net state variable are described in ISO 11843-1 and ISO 11843-2. ISO 11843-5:2008 extends the concepts in ISO 11843-2 to the cases of non-linear calibration. Examples are provided.