Nanostructure conducting molecularly imprinted polypyrrole film as a selective sorbent for benzoate ion and its application in spectrophotometric analysis of beverage samples

The benzoate anion was selectively extracted by electrochemically controlled solid-phase microextraction (EC-SPME) using a electro-synthesised nanostructure conducting molecularly imprinted polypyrrole (CMIP) film that imprinted for benzoate ions (template ion). The sorbent behaviors of CMIP were characterised using spectrophotometry analysis. The effect of pH, uptake and released times and potentials, template ion concentration, and interference were investigated, and experimental conditions optimised. The film exhibited excellent selectivity in the presence of potential interference from anions including salicylate, sorbate, citrate, phosphate, acetate and chloride ions. The calibration graph was linear (R2 ⩾ 0.993) in the range 1.1 × 10−5−5.5 × 10−4 mol L−1 and detection limit was 5.2 × 10−6 mol L−1. The relative standard deviation was less than 4.5% (n = 3). The CMIP film, as a solid-phase micro-extraction absorbent, was applied for the selective clean up and quantification of benzoate in beverage samples using the EC-SPME-spectrophotometric method. The results were in agreement with those obtained using HPLC analysis. This method has a good selectivity and mechanical stability and is disposable simple to construct. However, HPLC method is more selective for determination of benzoate in some food products which have interference compounds such as vanilla and flavoring agents.