Sensitive and selective colorimetric detection of Pb2+ by silver nanoparticles synthesized from Aconitum violaceum plant leaf extract

Highlights: • A new colorimetric sensor for the detection of Pb²⁺ using Aconitum violaceum leaf extract synthesized AgNPs was developed. • The color and spectral variations of the assay was easily detected by naked eye or spectrophotometer. • The bio-functionalized AgNPs were capable of detecting Pb²⁺ in the range of 0.5 × 10⁻⁷–2.5 × 10⁻⁵ M with good linearity. • The proposed method showed high specificity and good recoveries for Pb²⁺ in river water. - Abstract: In this work, we propose a simple and cost effective colorimetric method for the detection of Pb²⁺ using silver nanoparticles (AgNPs) prepared from the leaf extract of Aconitum violaceum. Due to the presence of significant amount of polyphenols in the extract, the AgNPs were successfully synthesized and were then characterized by UV–vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction (XRD) and transmission electron microscopy (TEM). The as prepared AgNPs were employed as colorimetric probes for the detection of Pb²⁺. In the presence of Pb²⁺, the biosynthesized AgNPs showed a color transformation from yellow to red, which was readily determined by UV–vis spectroscopy. The novel sensor exhibited good linearity for the detection of Pb²⁺ in the concentration range of 0.5 - 25 μM (R² = 0.996) with a detection limit (LOD) of 0.1 μM. Also, this sensing system presented a highly selective response for Pb²⁺ determination.