Benzoate ion determination in beverages by using a potentiometric sensor immobilized in a graphite matrix

The characteristics, performance, and application of an electrode, namely. Pt\Hg\Hg-2(Bzt)(2)\graphite, where Bzt stands for benzoate ion. are describ ed. This electrode responds to Bzt with sensitivity of 57.7 +/- 1.0 mV/deca de over the range 5 x 10(-4)-1 x 10(-1) mol l(-1) at pH 6.0-8.0 with a dete ction limit of 1.6 x 10(-4) mol l(-1). The electrode shows easy constructio n, fast response rime (between 10-30 s), low-cost, acid excellent response stability (lifetime > 6 months, in continuous use), The proposed sensor dis played good selectivity for benzoate in the presence of several carboxylate and inorganic anions. It was used to determine benzoate in various beverag es by means of the standard additions method. The results obtained by using this electrode compared very favorably with those given by the official AO AC spectrophotometric method and by a HPLC procedure as well. (C) 2001 Else vier Science B.V. All rights reserved.