Fig. 6

(A) Comparative UV–Vis absorption spectra of Q-TEPA(1 mM)-AgNPs after addition of solutions containing all competing metal ions (1 mM) prepared in tap water with and without Hg²⁺. (B) Comparative UV–Vis absorption spectra of Q-TEPA(1 mM)-AgNPs after addition of Hg²⁺ (50 µM and 1 mM) prepared in tap water. (C) Calibration curve (ΔAbs vs Hg²⁺ concentration) for Hg²⁺ detection using Q-TEPA(1 mM)-AgNPs including 50 µM Hg²⁺ solution prepared in tap water. The mixture was incubated at room temperature for 3 min and at pH 5.7.