Rapid determination of benzoate in soft drinks by solid-state benzoate ion selective sensor based on conducting polypyrrole film

Benzoate-doped polypyrrole (PPy-Bz) was prepared electrochemically by anodic polymerization of pyrrole in the presence of benzoate ion (Bz) in an aqueous solution and was used as a solid-state PPy-Bz ion selective sensor. The effect of polymerization conditions on the characteristics of the potential response of the sensors was also discussed. The solid-state PPy-Bz sensor, showed a near-Nernstian behavior over 9 × 10−5–2 × 10−2 mol L−1 Bz− with a detection limit of 5 × 10−5 mol L−1 in an aqueous solution. The potential response of the sensor was reproducible in the range pH 2–9 and was not affected by pH between 6 and 8. Selectivity of the sensor over diverse preservative reagents (sorbate, acetate and citrate) and inorganic salts was evaluated. The PPy-Bz sensor was applied for determination of Bz− ions in carbonated soft drinks by using potentiometry and the results are similar with values obtained by high-performance chromatography.