title: Selectivity in analytical chemistry: two interpretations for univariate methods.
abstract: Selectivity is extremely important in analytical chemistry but its definition is elusive despite continued efforts by professional organizations and individual scientists. This paper shows that the existing selectivity concepts for univariate analytical methods broadly fall in two classes: selectivity concepts based on measurement error and concepts based on response surfaces (the response surface being the 3D plot of the univariate signal as a function of analyte and interferent concentration, respectively). The strengths and weaknesses of the different definitions are analyzed and contradictions between them unveiled. The error based selectivity is very general and very safe but its application to a range of samples (as opposed to a single sample) requires the knowledge of some constraint about the possible sample compositions. The selectivity concepts based on the response surface are easily applied to linear response surfaces but may lead to difficulties and counterintuitive results when applied to nonlinear response surfaces. A particular advantage of this class of selectivity is that with linear response surfaces it can provide a concentration independent measure of selectivity. In contrast, the error based selectivity concept allows only yes/no type decision about selectivity.
authors.affiliation: Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szent Gellert ter 4., H-1111 Budapest, Hungary.
authors.forename: Zsanett
authors.initials: Z
authors.lastname: Dorkó
authors.affiliation: Faculty of Chemistry, University of Belgrade, Studentski Trg 12-16, 11000 Belgrade, Serbia.
authors.forename: Tatjana
authors.initials: T
authors.lastname: Verbić
authors.affiliation: Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szent Gellert ter 4., H-1111 Budapest, Hungary; MTA-BME Research Group of Technical Analytical Chemistry, Szent Gellert ter 4., H-1111 Budapest, Hungary. Electronic address: george.horvai@mail.bme.hu.
authors.forename: George
authors.initials: G
authors.lastname: Horvai
keywords: Analytical method; Error; Interference; Selectivity