Guaifenesin (GFS), phenylephrine (PHE) and paracetamol (PAR), drugs used in combination for the relief of cold and flu symptoms, were determined at electrochemically pretreated pencil graphite electrode. Differential pulse voltammetry (DPV) was used for the first time for the concomitant determination of the target compounds based on the electro-oxidation of PAR at 0.43 V, PHE at 0.74 V and GFS at 1.14 V in Britton-Robinson buffer pH 6.0. Under optimized experimental conditions, two linear ranges were obtained for PAR (2.50 × 10-6 M-1.00 × 10-5 M and 1.00 × 10-5 M-1.00 × 10-4 M) and for PHE and GFS linearity was proved between 5.00 × 10-6 M-2.00 × 10-4 M and 2.50 × 10-6 M-2.00 × 10-4 M, respectively. The detection limits were 8.12 × 10-7 M for PAR, 1.80 × 10-6 M for PHE and 8.29 × 10-7 M for GFS. The selective and sensitive DPV method and the electrochemically treated electrode were employed for simultaneous analysis of the analytes in pharmaceutical samples with good recoveries.
Keywords: differential pulse voltammetry; guaifenesin; paracetamol; pencil graphite electrode; pharmaceutical samples; phenylephrine.