Sensitive and selective colorimetric sensor detection of Sn (II): An aqueous, paper, and gel-based method by green biomimetic silver nanoparticles

Tin contamination in waters due to mining and natural activities in high concentrations can threaten human health. This research presents the development of a sensitive and selective colorimetric sensor in aqueous, paper, and gel-based to detect Sn²⁺. The development of such sensors is promising, with attractive advantages such as intense color, fast naked-eye response, and simple continuous fabrication. The addition of Sn²⁺ ions will change the color of the medium because curcumin (Cur) interacts with Sn²⁺, causing a decrease in free Cur, silver nanoparticles (AgNPs) becoming less stable, and a change in particle size. Colorimetric changes in Sn²⁺ were achieved by visual inspection within 10 min for aqueous-based and 20 min for paper and gel-based. The good linear relationship (R² = 0.9999) between Sn²⁺ and Δ absorption with a detection limit of up to 66.99 µg/L. This method is relatively scalable in determining Sn²⁺ and shows good recovery between 80 and 105 %. This colorimetric sensor gives good sensitivity to Sn²⁺ metal ions which is expected to become the basic technology for developing in-situ sensors to monitor Sn²⁺ levels in tin industrial waste.