Probe-infused polymer monolithic sensor for colorimetric detection of Pb2+ in environmental water samples and tobacco extracts

This study focuses on developing an affordable and cost-effective colorimetric solid-state optical sensor for target-specific naked-eye detection of Pb2+, offering significant potential for real-time environmental monitoring and public health applications. The indigenously developed porous polymer monolithic template, poly(lauryl methacrylate-co-ethylene glycol dimethacrylate) (poly(LMC-co-EGDMA) is infused with a chromoionophoric probe, i.e., 6,6-(naphthalene-1,5-diyl bis(diazene-2,1-diyl)bis(4-(butan-2-yl)phenol) (NDBP) to develop a durable/reusable solid sensor. The perforated structural assemblies of the porous poly(LMC-co-EGDMA) are analyzed using a range of microscopic, spectroscopic, and diffraction methods. The template features a homogeneous configuration of interlinked macro/mesoporous networks, allowing for the enhanced integration of NDBP probe molecules to facilitate rapid and improved Pb2+ detection. The fabricated sensor demonstrates a significant solid-state colorimetric shift from pale peach to deep maroon in proportion to Pb2+ concentration, with a precise absorption peak at 543 nm. The operational parameters of the poly(LMC-co-EGDMA)NDBP sensor are optimized to maximize the ion-sensing ability. The sensor demonstrates a linear signal response from 0 to 300 ppb for Pb2+ and corresponding detection and quantification limits of 0.28 and 0.93 ppb, respectively. The sensing effectiveness of the sensor using cigarette samples and natural water samples reveals outstanding accuracy with recovery results of ≥ 98.9 % (RSD ≤1.8 %) and ≥ 99.1 %, with RSD of ≤ 1.7 % from quadruplicate analysis. The proposed solid-state sensor offers exceptional sensitivity and selectivity for trace Pb²⁺ detection with a rapid response time of 40 s. The cost-effective and portable sensor provides a valuable tool for environmental monitoring and public health protection by enabling fast, on-site detection of the toxic Pb2+ in contaminated water and tobacco samples, particularly for developing and underdeveloped regions with limited access to sophisticated instruments. Its reusability and accuracy features offer a sustainable and practical solution for addressing widespread lead pollution, thus contributing to safer water quality assessments and pollution control.