Electrochemical Determination of Salicylic Acid at a New Biosensor Based on Polypyrrole-Banana Tissue Composite

An amperometric biosensor based on polypyrrole (PPy) coated on a disk graphite was developed by entrapment of banana tissue on surface the electrode. Polymer film was electrochemically synthesized by electro-oxidation of 0.1 M pyrrole in aqueous solution onto the biosensor. The PPy-modified bioelectrode showed a high catalytic activity toward the oxidation of salicylic acid (SA). The modified bioelectrode presented a linear response range for SA from 1.0 ×  10−7 up to 1.0 ×  10−4 M and limit of detection 8.9 × 10−8 M by differential pulse voltammetry. The diffusion coefficient of 6.46 ×  10−6 cm2 s−1 for SA was also obtained using chronoamperometry study. The responses of the unmodified electrode, PPy-modified electrode, and PPy-modified bioelectrode were compared. The biosensor was applied for the determination of salicylic acid in samples of plasma and milk.