Plasmonic chemosensing of W(<scp>vi</scp>), Pd(<scp>ii</scp>), Cr(<scp>iii</scp>), and Cs(<scp>i</scp>) in deep eutectic solvent using silver nanoparticles: green solvent toward optical point-of-use quality testing

The rapid and accurate detection of heavy metals is essential for reducing environmental pollution. Consequently, the quick and precise identification of heavy metals has become a primary challenge for scientists worldwide. In this study, an innovative and efficient optical chemosensor was developed based on a deep eutectic solvent (DES) for the selective identification of W(vi), Pd(ii), Cr(iii), and Cs(i) among 30 types of metal ions. A unique optical probe was fabricated by dissolving silver nanoparticles (T-AgNPrs) in a DES prepared from ChCl and EG. The color change of the T-AgNPrs-DES probe was observed with a smartphone, and a UV-vis spectrometer was used to validate it. The shift in the LSPR band in the UV-vis portion of the spectrum was used for plasmon optical sensing of candidate ions in samples. The proposed optical sensor demonstrated a high degree of linearity in the 0.01 to 0.8 μg ml^-1 concentration range for W(vi), Pd(ii), Cr(iii), and Cs(i), respectively. The suggested method for using the T-AgNPrs-DES probe to detect W(vi), Pd(ii), Cr(iii), and Cs(i) had limits of detection (LOD) of 0.02, 0.005, 0.003, and 0.006 μg ml^-1, respectively. Notably, the proposed optical chemosensor can detect selected ions in a human urine sample with a minimum concentration of 0.01 μg ml^-1. Throughout this study, it was demonstrated that combining nano-based materials and DESs presents innovative and effective strategies for developing enhanced sensing devices. This approach results in hybrid devices that exhibit better signal-to-noise ratios, linearity, and selectivity.