Analytical Sciences

Colorimetric Sensor for Thiocyanate Based on Anti-aggregation of Gold Nanoparticles in the Presence of 2-Aminopyridine

Yuqi ZHAO,* Ruxin LIU,* Xiaoqian CUI,** Qingjie FU,* Miao YU,* Qiang FEI,* Guodong FENG,* Hongyan SHAN,* and Yanfu HUAN*

*College of Chemistry, Jilin University, Changchun 130023, PR China
**Department of Emergency and Critical Care, The Second Hospital of Jilin University, Changchun 130041, PR China

Based on the anti-aggregation mechanism of citrate stabilized gold nanoparticle (AuNPs), a new specific and sensitive colorimetric sensor for thiocyanate (SCN⁻) was developed. In this scheme, the AuNPs were aggregated in the presence of the aggregating agent 2-aminopyridine (2-AP) due to electrostatic attraction. The solution color changed from red to blue. When SCN⁻ was present, SCN⁻ formed a sulfur–gold bond with the AuNPs to protect the AuNPs from aggregation. Thiocyanate can be detected by the color change of the solution from blue to red. The results showed that the absorbance ratio A₆₇₅/A₅₂₀ was linear with the concentration of SCN⁻ in the range of 0.4 – 1.2 μmol L⁻¹ by UV-Vis spectroscopy. The limit of detection (LOD) of this assay was 0.37 μmol L⁻¹. The system also had excellent selectivity and anti-interference ability. In addition, this method was successfully used for the detection of SCN⁻ in actual water samples and achieved good results.

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