γ-Irradiated Chitosan Stabilized Silver Nanoparticles as Novel Colorimetric Sensors for Mercury(II) and Iron(II) Detections in Real Samples

Abstract

This contribution presents a novel method for simple and rapid colorimetric detection of Hg(II) and Fe(II) ions in real samples using silver nanoparticles (AgNPs). The AgNPs were green-synthesized in aqueous solution using γ-irradiated chitosan as a reducing and stabilizing agent. The γ-chitosan stabilized AgNPs were found to be spherical with a diameter of 11.39 ± 2.23 nm. The AgNPs are highly selective for Hg(II) and Fe(II) ions, and when Hg(II) is present in solution, the yellowish AgNPs solution is turned to light yellow, while in the presence of Fe(II) the color of the AgNPs solution is changed to dark brown. The change of solution color is proposed via (i) The reoxidation of Ag(0) in AgNPs to Ag(I) for the Hg(II) detection and (ii) The aggregation of AgNPs in solution for the Fe(II) detection. Under optimal conditions, the method exhibits good linearity from 0.5 to 5.0 ppm (r 2 = 0.9965) for Hg(II) and from 0.05 to 10.0 ppm (r 2 = 0.9994) for Fe(II). The limit of detections (LODs) for Hg(II) and Fe(II) analyses are 0.22 and 0.18 ppm, respectively. Tap waters spiked with both ions show excellent percentage recoveries (93.48–99.53%) with good precision (%RSD < 5%). The developed method was for the first time successfully applied to the assessment of Fe(II) contents in pharmaceutical products, and has potential to be developed as an effective detection kit for assessing Hg(II) and Fe(II) ions in real samples. © 2023, King Fahd University of Petroleum & Minerals.