Green Spectrophotometric Estimation of Minor Concentrations of Methyldopa and Terbutaline Sulphate in Pure Forms and Tablets Using Polyvinylpyrrolidone-Capped Silver Nanoparticles

Sensitive and simple colorimetric method was developed for determination of methyldopa and terbutaline sulphate in pure and pharmaceutical dosage forms. The method was based on reduction of silver ions by the cited drugs in basic medium at 90 °C to silver nanoparticles in the presence of stabilizing agent as polyvinylpyrrolidone. The formed silver nanoparticles were distinguished by UV-Vis absorption spectroscopy indicating the characteristic surface plasmon resonance which can be also observed as intense yellow color solution. The plasmon absorbance of the silver nanoparticles was measured at 410 nm for quantitative estimation of methyldopa and terbutaline sulphate over the range of 80-480 and 40-600 ng/ ml respectively. Limit of detection was obtained as 26, 13 ng/ ml for methyldopa and terbutaline sulphate respectively. The eco-friendly developed method could be successfully applied to the pharmaceutical formulations with studying the interference of different excipients.