COMMISSION ON GENERAL ASPECTS OF ANALYTICAL CHEMISTRY
Title: Selectivity and Specificity in Analytical Chemistry
Chairman : J. Vessman
Members: J.F. van Staden, R.I. Stefan, A. Fajgelj, K. Danzer,
W. Lindner, H. Muller, D.T. Burns
Completion Date: 2001 - project completed
To develop an IUPAC recommendation on the proper definition and
extract from the Introduction of the provisional recommendations
A very important quality criterion of an analytical method is its capability
to deliver signals that are free from interferences and give "true results".
The ability to discriminate between the analyte and interfering components
has for many years been expressed as the selectivity of a method and
measurement system. One clear definition is the following: " Selectivity
of a method refers to the extent to which it can determine particular
analyte(s) in a complex mixture without interference from other components
in the mixture" (1). However, the same meaning has often been given
to the term specificity (2). Following earlier concern about the use
of these terms (3) IUPAC clarified this overlap by expressing the view
that "Specificity is the ultimate of Selectivity" (4). The Compendium
of Analytical Nomenclature, Definitive Rules 1997, only mentions these
important terms under "related papers" in Chapters 2 and 18 (5). As
there is still a tendency to mix up these two terms a discussion clarifying
the rationale behind the need to differentiate the use of the terms
is given, followed by particular recommendations. [see full text for
ref (1) to (5)]
The project was discussed in Berlin (aug 1999) and is in progress.
A draft was evaluated by commission V.1 at their 2000 annual meeting
in Lisbon and after finalised.
The following recommendations are proposed:
- That the term Selectivity be promoted. Selectivity is the
recommended term in analytical chemistry to express the extent to
which a particular method can determine analytes under given conditions
in the presence of interferences from other components in the matrix.
Selectivity can be graded. To avoid confusion the use of the term
specificity for the same concept is to be discouraged.
- Definition of Selectivity. Selectivity of a method refers
to the extent to which it can determine particular analytes under
given conditions in mixtures or matrices, simple or complex, without
interferences from other components.
A final document is submitted to public review comments until 30 September
> see provisional
Project completed - IUPAC Recommendations 2001, entitled 'Selectivity
in analytical chemistry ' is published in Pure
73(8), pp. 1381-1386, 2001.
Last update: 20 November 2001