High-Performance Colorimetric Detection of Thiosulfate by Using Silver Nanoparticles for Smartphone-Based Analysis

Area of Science:

• Analytical Chemistry
• Materials Science
• Environmental Science

Background:

• Developing selective sensors for thiosulfate (S₂O₃^2-) in aqueous solutions is challenging due to anion interference.
• Existing methods for thiosulfate detection often lack the sensitivity or selectivity required for real-world environmental monitoring.

Purpose of the Study:

• To develop a highly selective and sensitive colorimetric sensor for thiosulfate detection.
• To enable rapid, on-site analysis of thiosulfate using a smartphone-based platform.

Main Methods:

• Fabrication of silver nanoparticles (AgNPs) for colorimetric detection of S₂O₃^2-.
• Characterization of AgNPs using UV-vis, TEM, DLS, SEM, and XPS analyses.
• Development of a smartphone application for quantitative analysis based on RGB color values.

Main Results:

• The AgNPs sensor demonstrated a distinct color change from yellow to brown upon interaction with S₂O₃^2-.
• High sensitivity was achieved with detection limits of 1.0 μM (naked-eye) and 0.2 μM (UV-vis spectroscopy).
• A linear response was observed for S₂O₃^2- concentrations from 0.2 μM to 2.0 μM (R² = 0.998) and in 0-20.0 μM solutions using smartphone analysis.

Conclusions:

• The developed AgNPs-based colorimetric sensor provides a selective and sensitive method for thiosulfate detection.
• The smartphone integration allows for convenient and rapid on-site quantitative analysis of thiosulfate in environmental samples.
• The sensor shows significant potential for practical applications in environmental monitoring.