Mucilage-capped silver nanoparticles for electrochemical quantification of methyl red in drinking water samples

Herein, we report a new electrochemical sensor based on silver nanoparticles (AgNPs) to quantify methyl red (MR) in drinking water. Firstly, AgNPs were greenly synthesized using mucilage natural polymer for the reduction of Ag + and subsequent stabilization of the formed AgNPs. The formation of AgNPs was confirmed by monitoring their characteristic absorption peak at a wavelength of 425 nm and characteristic oxidation potential at 0.035 V using ultraviolet–visible spectroscopy and square wave voltammetry (SWV), respectively. Transmission electron microscopy also confirmed the synthesis of spherical AgNPs with a size range of 10 to 30 nm, while scanning electron microscopy showed the morphology of glassy carbon electrode (GCE) after modification with AgNPs. Additionally, the electrocatalytic activity of AgNPs/GCE was approved by cyclic voltammetry, electrochemical impedance spectroscopy, and SWV. The highly electrocatalytic mucilage-AgNPs were employed as a GCE modifier to quantify MR under optimized conditions of scan rate (0.1 V/s), amplitude (0.025 V), and pH (6) using SWV. The sensor showed a limit of detection of 1.5 picomolar and high selectivity in the presence of some possible interfering dyes in drinking water sources. Additionally, after spiking the drinking water samples with MR, the sensor showed acceptable recovery values.