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Silver nanoplates-based colorimetric iodide recognition and sensing using sodium thiosulfate as a sensitizer
Xinyan Hou1, Shu Chen1, Jian Tang1
1Key Laboratory of Theoretical Chemistry and Molecular Simulation of Ministry of Education of China, School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan 411201, China.
Analytica Chimica Acta
|April 29, 2014
Summary
A new colorimetric method uses silver nanoplates and sodium thiosulfate to detect iodide ions. This sensitive and selective approach allows for visual or spectrophotometric identification of iodide, even in food samples like kelp.
Area of Science:
- Nanomaterials Science
- Analytical Chemistry
- Environmental Science
Background:
- Iodide ion (I-) detection is crucial for environmental and biological monitoring.
- Existing methods for iodide sensing often lack selectivity or sensitivity.
- Silver nanoplates (AgNPs) exhibit unique optical properties sensitive to their chemical environment.
Purpose of the Study:
- To develop a novel, highly selective, and sensitive colorimetric method for iodide ion detection.
- To utilize the protective effect of iodide on triangular silver nanoplates (TAg-NPs) in the presence of sodium thiosulfate.
- To enable visual and spectrophotometric quantification of iodide ions.
Main Methods:
- A colorimetric assay based on the reaction between triangular silver nanoplates (TAg-NPs) and iodide ions (I-) in the presence of sodium thiosulfate (Na2S2O3).
- Induction of TAg-NP protection by I- and Na2S2O3 due to insoluble silver iodide (AgI) formation, confirmed by High-Resolution Transmission Electron Microscopy (HRTEM).
- Monitoring changes in localized surface plasmon resonance (LSPR) absorption peak wavelength using UV-vis spectrophotometry.
Main Results:
- Sodium thiosulfate acts as a sensitizer, enhancing selectivity and sensitivity for I- detection.
- The shift in maximum absorption wavelength (Δλ) is proportional to I- concentration from 1.0×10⁻⁹ to 1.0×10⁻⁶ mol L⁻¹.
- The method achieved a detection limit of 1.0×10⁻⁷ mol L⁻¹ for I-, with no observable color change induced by other halide ions.
- Successful application of the method for determining I- in kelp samples.
Conclusions:
- A robust and selective colorimetric sensing platform for iodide ions has been established using TAg-NPs and Na2S2O3.
- The developed method offers a simple, rapid, and cost-effective alternative for iodide determination.
- This technique holds potential for practical applications in food analysis and environmental monitoring.
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