Polarographic Analysis of Quetiapine in Pharmaceuticals

The voltammetric behaviour of quetiapine (QTP) was studied using direct current (DCt), differential pulse (DPP) and alternating current (ACt) polarography. The drug manifests cathodic waves over the pH range of 6 – 11.8. The waves were characterized as being irreversible, diffusion-controlled with limited adsorption properties. At pH 8, the diffusion current-concentration relationship was rectilinear over the range of 8 – 44 μg/mL and 4 – 44 μg/mL using DCt and DPP modes, respectively, with minimum detection limits (LOD) of 0.06 μg/mL and 0.04 μg/mL using the DCt and DPP modes, respectively. The diffusion-current constant (Id) is 1.36 ± 0.04 (n = 10). The proposed method was successfully applied to the determination of the studied compound both in pure form and in formulations. The results obtained were favourably compared with those obtained using a reference method. A pathway for the electrode reaction was postulated.