In-situ highly selective colorimetric trace level recognition of lead and copper ion in real samples by silver nanoparticles

Abstract

In the current study, an advanced and highly discriminating scheme was developed to detect Pb+2 and Cu+2 using Maltol-capped silver nanoparticles (McAgNPs). Various metal ions i.e. Fe+3, Ce+4, Ni+2, Mg+2, Cd+2, Mo+6, Zn+2, Na+1, Co+2, Ba+2, Cu+2, and Pb+2 was studied, among them, only Pb+2 and Cu+2 caused substantial changes in solution color, shifting from yellow to green and pink immediately after adding AgNPs. This color transformation was accompanied by the emergence of new visible bands at 674 nm for Pb+2 and 608 nm for Cu+2. The characterization of complexes (McAgNPs-Pb+2 and McAgNPs-Cu+2) was carried out by state of art techniques such as visible spectrophotometry, Fourier transform infrared spectroscopy (FTIR), and Atomic force microscopy (AFM). AFM results indicated an increase in particle size after the interaction (i.e., 40 to 150 (Cu+2) and 250 nm (Pb+2)). McAgNPs are remarkably selective for Pb+2 and Cu+2 in the presence of other metal ions (i.e., Fe+3, Ce+4, Mg+2, Ni+2, Mo+6, Zn+2, Cd+2, Co+2, Na+1, Ba+2). The pH effect on both complexes was also investigated over a range of pH 1.0–13.0, revealing that McAgNPs-Pb+2 remained stable across the entire pH range, while McAgNPs-Cu+2 was stable only under acidic conditions. Both interactions exhibited good linearity (0.4–1.0 μM), binding stoichiometry (1-Pb+2:1McAgNPs and 2-Cu+2:3McAgNPs), and their respective limit of detection (LOD) was found to be 0.035 for McAgNPs-Cu+2 and 0.067 μM for McAgNPs-Pb+2. Additionally, the suggested scheme was effectively utilized to detect Pb+2 and Cu+2 in environmental (e.g., lake, tap, mineral, and well water) and biological (e.g., urine and plasma) samples, with recoveries ranging from 94.7 to 105%. Consequently, our approach paves the way for creating innovative and efficient suitable nanoprobe for highly selective and sensitive sensing.