High reproducibility of facile Pb(II) ion electrochemical sensor based on BIM/SBA-15

A cost-effective electrochemical sensor was developed for the selective detection of Pb(II) ions using a new bis-indolylmethane ( BIM ) derivative immobilised on SBA-15 mesoporous silica, deposited onto a carbon screen-printed electrode (CSPE). BIM derivative plays a key role in enhancing Pb(II) ions selectivity through its electron-rich nitrogen donor sites, which facilitate stable complexation with Pb(II) ions. Characterisation via field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) confirmed successful incorporation of BIM into SBA-15's hexagonal mesopores. The sensor exhibited electrocatalytic activity, detecting Pb(II) ions oxidation at −0.52 V vs Ag/AgCl using differential pulse voltammetry (DPV). It demonstrated a linear response over the concentration range of 1 × 10 −5 M to 4 × 10 −3 M (R 2 = 0.9963), with a detection limit (LOD) of 6.8 × 10 −6 M. Importantly, the detection potential at −0.52 V vs Ag/AgCl was observed to be characteristic only for Pb(II) ions, thereby minimizing interference from other heavy metals and organic compounds that are not electroactive within this potential window. The sensor showed a high reproducibility (2.5 % of RSD), attributed to the stability of the current response enabled by the proposed fabrication. Application to Allium tuberosum samples yielded the highest recovery rate of 97.61 %, aligned with results obtained via atomic absorption spectroscopy (AAS). Notably, this specific combination of BIM derivative and SBA-15 on CSPE for Pb(II) ions sensing has not been previously reported, marking a key innovation of this study. This simple, low-maintenance sensor offers a promising alternative for real-time, on-site monitoring of Pb(II) ions contamination, contributing to environmental and food safety application. • New BIM/SBA-15 electrochemical sensor developed for selective Pb(II) ion detection. • Detection limit of 6.8 × 10 −6 M with R 2 = 0.9963 over 1 × 10 −5 to 4 × 10 −3 M range. • Pb(II) ion detected at −0.52 V using DPV with good electrocatalytic response. • Sensor validated in Allium tuberosum with the highest recovery rate of 97.6 %. • Cost-effective sensor offers sustainable alternative to conventional Pb(II) ion detection.