a b s t r a c t
The construction, evaluation and application of a new potentiometric sensor, namely, Pt|Hg|Hg2(SOB)2
|Graphite, where SOB stands for sorbate ion, are described. This electrode has a wide linear dynamic
range between 5.0 107 and 1.0 102 mol L1 with a near-Nernstian slope of (58.6 ± 1.3) mV decade
1 and a detection limit of 4.3 107 mol L1. The potentiometric response is independent of the
pH of the solution in the pH range 6.0–9.0. The electrode is easily constructed at a relatively low-cost
with fast response time (within 15–30 s) and can be used for a period of 4 months without significant
change in its performance characteristics. The proposed sensor displayed good selectivities over a variety
of other anions (carboxylates and inorganic anions). The potentiometric sensor was successfully applied
to the determination of sorbic acid in real food samples, that is, soft drinks, skim yogurts, jams and
sauces.