Plasmonic chemosensing of W(vi), Pd(ii), Cr(iii), and Cs(i) 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 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, respectively. Notably, the proposed optical chemosensor can detect selected ions in a human urine sample with a minimum concentration of 0.01 μg ml. 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.