Fabrication of reusable probe impregnated polymer monolithic sensor for the visual detection of Cd²⁺ in natural...

This work demonstrates the fabrication of a simple, low-cost naked-eye colorimetric solid-state sensor model for selective sensing of Cd²⁺. The sensor was developed using a polymer monolithic architect; namely, poly(n-allylthiourea-co-ethyleneglycol dimethacrylate) (poly(ATU-co-EGD) imbued with the chromophoric probe, 3-(quinoline-8-yldiazenyl)quinoline-2,4-diol (QYQD). The concocted indigenous perforated structural assemblies were studied through various microscopic, spectroscopic, and diffraction techniques. The template possessed a uniform arrangement of interconnected macro/mesoporous networks available for the maximum hooking of the QYQD probe moieties for the rapid and enhanced Cd²⁺ sensing process. The developed sensor offered an enhanced solid-state color transition response from yellow to dark meron for a proportional concentration increase of Cd²⁺ exhibiting precise absorption spectra with λ_max at 475 nm. The relative stoichiometric binding ratio of the QYQD probe with Cd²⁺ was observed to be 2:1. The enhanced working conditions of the developed poly(ATU-co-EGD)QYQD sensor were tuned by validating various analytical conditions. The sensor exhibited a linear response signal from 2 to 150 ppb of Cd²⁺, and the corresponding LOD and LOQ values were 0.31 and 1.03 ppb, respectively. The efficacious performance drive of the sensor was validated in real water and cigarette samples that showed excellent data accuracy with a recovery value of ≥ 99.72% (n = 3).