Preferred Label : potentiometric selectivity coefficient;
IUPAC definition : A coefficient which defines the ability of an ion-selective electrode to distinguish
a particular ion from others. The selectivity coefficient, KA,Bpot, is evaluated by
means of the emf response of the ion-selective electrode in mixed solutions of the
primary ion, A, and interfering ion, B (fixed interference method) or less desirable,
in separate solutions of A and B (separate solution method). The activities of the
primary ion, A, and the interfering ion, B, at which KA,Bpot is determined should
always be specified, as the value of KA,Bpot is defined by the modified Nikolsky–Eisenman
equation. The smaller the value of KA,Bpot the greater the electrode's preference
for the principal ion, A. Comment: The terms selectivity constant and selectivity
factor are frequently used instead of selectivity coefficient. However, in order to
standardize the terminology associated with ion-selective electrodes, use of the term
selectivity coefficient is recommended, as is the fixed interference method for its
evaluation. This selectivity coefficient is not identical to the similar term used
in separation science.;
Origin ID : P04791;
See also
A coefficient which defines the ability of an ion-selective electrode to distinguish
a particular ion from others. The selectivity coefficient, KA,Bpot, is evaluated by
means of the emf response of the ion-selective electrode in mixed solutions of the
primary ion, A, and interfering ion, B (fixed interference method) or less desirable,
in separate solutions of A and B (separate solution method). The activities of the
primary ion, A, and the interfering ion, B, at which KA,Bpot is determined should
always be specified, as the value of KA,Bpot is defined by the modified Nikolsky–Eisenman
equation. The smaller the value of KA,Bpot the greater the electrode's preference
for the principal ion, A. Comment: The terms selectivity constant and selectivity
factor are frequently used instead of selectivity coefficient. However, in order to
standardize the terminology associated with ion-selective electrodes, use of the term
selectivity coefficient is recommended, as is the fixed interference method for its
evaluation. This selectivity coefficient is not identical to the similar term used
in separation science.
