Evaluation of the electrochemical behavior and analytical potentialities of a carbon paste electrode modified with a ruthenium (III) piperidinedithiocarbamate complex

The preparation and electrochemical characterization of a carbon paste electrode modified with bis(N,N-piperidinedithiocarbamate)-μ-tris(N,N-piperidinedithiocarbamate)diruthenium(III) complex, α-[Ru2(Pip)5]Cl are described. The best voltammetric response was obtained for a 10% (m/m) α-[Ru2(Pip)5]Cl content in the paste, potassium acid phthalate solution pH 4.0 as supporting electrolyte and scan rate of 100 mV s-1. The analytical potentialities of the electrode have been evaluated using l-ascorbic acid (vitamin C) as a probe. A sensitive linear voltammetric response for l-ascorbic acid was obtained in the concentration range 4.50-113 × 10-5 mol l-1 (7.92-200 mg l-1) with a slope of 1.12 × 104 μA mol-1, and a detection limit (3σ/slope) of 7.00 × 10-6 mol l-1 using cyclic voltammetry. The concentrations of l-ascorbic acid in pharmaceutical formulations (tablets and liquid) were determined using the modified electrode and compared with an iodimetric procedure with good agreement at the 95% confidence and relative error lower than 1%.