Use of carbon paste electrode and modified by gold nanoparticles for selected macrolide antibiotics determination as standard and in pharmaceutical preparations

Abstract

In this work, carbon paste electrode (CPE) and carbon paste electrode modified with gold nanoparticles (AuNPs/CPE) were employed with rapid direct anodic square wave voltammetry (SWV) for macrolide antibiotics erythromycin ethylsuccinate (EES), azithromycin (AZI), clarithromycin (CLA) and roxithromycin (ROX) determination. The surface of working electrodes was morphologically characterized by scanning electron microscopic (SEM) measurements whereby the presence of randomly distributed AuNPs of 10 nm diameter size on CPE surface was confirmed by energy dispersive spectrometer (EDS). SWV determination of four macrolide antibiotics using CPE was performed in aqueous Britton-Robinson buffer solutions (pH 2.0 to 11.98) showing that oxidation signals strongly depend upon pH (at pH ≥ 6) and exhibited the most favorable characteristics at pH 8.0 in the case of EES and pH 11.98 in the case of AZI, CLA and ROX. Under optimized conditions, the SWV method using CPE enables determination of all investigated macrolide antibiotics in low μg mL−1 concentration ranges with relative standard deviations (RSDs) lower than 6% and achieved detection limits (LODs) as 0.18, 0.045, 1.43 and 0.30 μg mL−1 for EES, AZI, CLA and ROX, respectively. In the case of AZI and ROX, it was demonstrated that the use of AuNPs/CPE as working electrode could additionally improve the results obtained with the SWV method concerning exhibited sensitivity, reproducibility and linear concentration range, due to the electrocatalytic properties of synthesized AuNPs. The optimized experimental parameters with the use of SWV method and CPE or AuNPs/CPE were successfully applied for determination of ROX and AZI in their pharmaceutical preparations Runac® and Hemomycin®, respectively. The reliability of the elaborated procedures and thus the accuracy of the obtained results were validated by comparing them with those obtained by means of HPLC-DAD measurements.