Voltammetric behaviour of the antimycotic terbinafine at the hanging mercury drop electrode

Terbinafine is adsorbed on a hanging mercury drop electrode at pH 6.0 and gives a single wave at −1.47 vs. AgAgCl reference electrode, due to olefinic double bond reduction. The electrochemical process is irreversible and fundamentally controlled by adsorption. A systematic study of the several instrumental and accumulation variables affecting the adsorptive stripping (AdS) response was carried out using square wave voltammetry (SWV, Osteryoungʹs method) and differential pulse voltammetry (DPV) as redissolution techniques. The limits of detection were 1.7 × 10−10 mol l−1 (AdS-SWV) and 6.3 × 10−7 mol l−1 (AdS-DPV). The coefficients of variation were 2.71% (AdS-SWV) and 2.63% (AdS-DPV) at 4 × 10−8 mol l−1 (n = 10). For the determination of terbinafine in formulations and spiked human urine samples, a method based on a preseparation step at a solid phase C-18 cartridge and on the AdS-SWV procedure is proposed.