Anodic Polaroqraphic Determination of lsradipine in Pharmaceutical Formulations

The anodic behaviour of isradipine was studied using cyclic voltammetry (CV), direct current (DC_t) and differential-pulse (DPP) polarography. lsradipine exhibited well-defined anodic polarographic waves over the pH range of 4–8 in Britton-Robinson buffer (BRb). At pH 6, the analytical pH, the diffusion-current constant (Id) was 2.12 ± 0.42 (n = 4). The oxidation potential is −0.10 V vs AgIAgCl reference electrode with correlation coefficients of 0.9977 and 0.9948 in the DC_t and DPP modes, respectively. The current-concentration plots were rectilinear over the ranges 5–14 µg/ml and 2.4–12 µg/ml using the DC_t and DPP modes, respectively. The lower detection limit was 1.12 µg/ml (3.02 x 10⁻⁶ M) adopting the DPP mode. The proposed method was applied to commercial tablets and capsules, the % recoveries were 100.52 ± 1.267 and 99.4 ± 0.87 (n = 6) for the tablets and 101.3 ± 1.57 and 100.7 ± 2.10 (n = 6) for the capsules adopting both DC_t and DPP modes, respectively. The number of electrons involved in the electrode process was accomplished and a proposal of the electrode reaction was presented.