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The reduction of luvastatin (FLV) at a hanging mercury-drop electrode (HMDE) was studied by square-wave adsorptive-stripping voltammetry (SWAdSV). FLV can be accumulated and reduced at the electrode, with a maximum peak current intensity at a potential of approximately -1.26 V vs. AgCl/Ag, in an aqueous electrolyte solution of pH 5.25. The method shows linearity between peak current intensity and FLV concentration between 1.0 × 10-8 and 2.7 × 10-6 mol L-1. Limits of detection (LOD) and quantification (LOQ) were found to be 9.9 × 10-9 mol L-1 and 3.3 × 10-8 mol L-1, respectively. Furthermore, FLV oxidation at a glassy carbon electrode surface was used for its hydrodynamic monitoring by amperometric detection in a flow-injection system. The amperometric signal was linear with FLV concentration over the range 1.0 × 10-6 to 1.0 × 10-5 mol L-1, with an LOD of 2.4 × 10-7 mol L-1 and an LOQ of 8.0 × 10-7 mol L-1. A sample rate of 50 injections per hour was achieved. Both methods were validated and showed to be precise and accurate, being satisfactorily applied to the determination of FLV in a commercial pharmaceutical. [ABSTRACT FROM AUTHOR]

The electrooxidative behavior of citalopram (CTL) in aqueous media was studied by cyclic voltammetry (CV) and square-wave voltammetry (SWV) at a glassy-carbon electrode. The electrochemical behaviour of CTL involves two electrons and two protons in the irreversible and diffusion controlled oxidation of the tertiary amine group. The maximum analytical signal was obtained in a phosphate buffer (pH = 8.2). For analytical purposes, an SWV method and a flow-injection analysis (FIA) system with amperometric detection were developed. The optimised SWV method showed a linear range between 1.10 × 10-5-1.20 × 10-4 mol L-1, with a limit of detection (LOD) of 9.5 × 10-6 mol L-1. Using the FIA method, a linear range between 2.00 × 10-6-9.00 × 10-5 mol L-1 and an LOD of 1.9 × 10-6 mol L-1 were obtained. The validation of both methods revealed good performance characteristics confirming applicability for the quantification of CTL in several pharmaceutical products. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of citalopram was studied by square-wave and square-wave adsorptive-stripping voltammetry (SWAdSV). Citalopram can be reduced and accumulated at a mercury drop electrode, with a maximum peak current intensity being obtained at a potential of approximately - 1.25 V vs. AgCl/Ag, in an aqueous electrolyte solution of pH 12. A SWAdSV method has been developed for the determination of citalopram in pharmaceutical preparations. The method shows a linear range between 1.0 × 10-7 and 2.0 × 10-6 molL-1 with a limit of detection of 5 × 10-8molL-1 for an accumulation time of 30s. The precision of the method was evaluated by assessing the repeatability and intermediate precision, achieving good relative standard deviations in all cases (≤2.3%). The proposed method was applied to the determination of citalopram in five pharmaceutical products and the results obtained are in good agreement with the labeled values. [ABSTRACT FROM AUTHOR]