AOAC GFA Stakeholder Program Meeting Book (August 27, 2023)

Current Definition VIM4 Second Committee Draft Definition

3.20 Measurand: The quantity

measurand quantity intended to be measured

NOTE 1 The quantity mentioned in the definition is an individual quantity that is identified as the property of a given object. NOTE 2 The specification of a measurand typically requires knowledge of the general quantity, description of the state of the object carrying the quantity, including any quantity having a relevant effect on the quantity intended to be measured, and, if required, the chemical or biological entities involved. NOTE 3 In some cases the measurand is specified by a documented and accepted measurement procedure or method. In laboratory medicine this is referred to as a “procedure defined measurand”. ISO/TC 334 refers to this as an “operationally defined measurand” (see [20], definition 3.7). In these cases only results obtained by the same procedure can be compared. NOTE 4 In the past the term “measurand” was used to refer to both the quantity intended to be measured and the quantity being measured, i.e., the quantity with which the measuring system interacts. Given that, despite the best efforts of the measurer, the quantity intended to be measured might not be the same as the quantity being measured, it is important to acknowledge this difference and then this ambiguity was removed by calling “measurand” only the former. NOTE 5 The measurement, along with the measuring system and the conditions under which the measurement is carried out, might change the object such that the quantity which interacts with the measuring system may differ from the measurand as defined. In this case, adequate correction to the measured value may be necessary depending on the target uncertainty. NOTE 6 The term “analyte”, or the name of a substance or compound, should not be confused with the term “measurand”, because analytes are not quantities.

intended to be measured (the specification of the measurand should be sufficiently detailed to avoid any ambiguity). See also “analyte” definition.