Experimental procedures for the determination of amperometric selectivity coefficients

Procedures for the determination of amperometric selectivity coefficients, expressing the extent of interference of foreign electroactive substances on the amperometric sensing of the target analyte, are critically assessed. Separate solution (equiconcentration, matched current, measurement matching sample composition, separate calibration) and mixed solution methods (fixed analyte and fixed interferent, with single or multiple addition, alternate analyte and interferent addition) are examined. The performance of different methods and procedures with a model system (catechol and ferrocyanide) and a system with direct interaction between the electroactive species (dopamine and ascorbic acid) is experimentally explored. The advantages of mixed solution methods are discussed.