In the present paper, poly(azure A) (PAA) films were electrosynthetized in the presence of different doping anions on disposable screen-printed carbon electrodes (SPCEs). The anions used included inorganic monoatomic (chloride and fluoride), inorganic polyatomic (nitrate and sulfate) and organic polyatomic (dodecyl sulfate, DS) species. The coated electrodes thus obtained were characterized by electrochemical techniques and SEM. They showed improved electrocatalytic activities towards hydrogen peroxide oxidation compared to that of a bare SPCE. In particular, the insertion of DS anions inside PAA films provided a special sensitivity to the electrocatalysis of H₂O₂, which endowed these electrodes with promising analytical features for H₂O₂ quantification. We obtained a wide linear response for H₂O₂ within a range of 5 µM to 3 mM and a limit of detection of 1.43 ± 0.10 µM (signal-to-noise ratio of 3). Furthermore, sensitivity was 72.4 ± 0.49 nA·µM-1∙cm-2 at a relatively low electrocatalytic oxidation overpotential of 0.5 V vs. Ag. The applicability of this boosted system was tested by the analysis of H₂O₂ in commercial samples of a hair lightener and an antiseptic and was corroborated by spectrophotometric methods.
Keywords: conducting polymers; disposable screen-printed electrodes; electrochemical sensor; hydrogen peroxide; poly(azure A); sodium dodecyl sulfate.