Colorimetric Sensing of Pb2+ Ion by Using Ag Nanoparticles in the Presence of Dithizone

Abstract

Colorimetric analysis of heavy metal ions can be realized by the aid of Ag nanoparticles to improve the analytical characteristics. The method is based on the localized surface plasmon resonance (LSPR) properties of the Ag nanoparticles (AgNPs). In this work, we applied the AgNPs with the addition of dithizone to further improve the selectivity and sensitivity of Pb2+ analysis. Colorimetric sensing of Pb2+ ions based on the polyvinyl alcohol (PVA)-stabilized-colloidal AgNPs in the presence of dithizone is reported. A linear decrease in the AgNPs LSPR absorbance at 421 nm was observed along with the increase in the Pb2+ concentration in the range of 0.50–10 µg/L. The other ions give a minor change in the LSPR absorbance of colloidal AgNPs. The Pb2+ limit of detection, the limit of quantification, and sensitivity were found to be 0.64 ± 0.04 µg/L, 2.1 ± 0.15 µg/L, 0.0282 ± 0.0040 L/µg (n = 5), respectively. The obtained sensitivity is comparable with that of the immunosensing method. The proposed method could offer a good alternative for colorimetric analysis of Pb2+ ions by using nanoparticles in the presence of ligands, which can improve selectivity.