Analytical Sciences

A Fluorescent Chemosensor for Hg²⁺ Based on a Rhodamine Derivative in an Aqueous Solution

Chun-Yan LI,* Yu ZHOU,* Yong-Fei LI,** Chun-Xiang ZOU,* and Xue-Fei KONG*

*Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105, P. R. China
**College of Chemical Engineering, Xiangtan University, Xiangtan 411105, P. R. China

In this paper, we unveil a novel rhodamine compound-based fluorescent chemosensor (compound 1) for fluorescent detection of Hg²⁺ in an aqueous solution. The fluorescence enhancement of compound 1 was attributed to the formation of a complex between compound 1 and Hg²⁺ by 1:1 complex ration (K = 8.0 × 10⁴), which has been utilized as the basis of fabrication of the Hg²⁺-sensitive chemosensor. A comparison of this method with some other fluorescence methods for the determination of Hg²⁺ indicated that this method has high selectivity and good water solubility. The analytical performance characteristics of the proposed Hg²⁺-sensitive chemosensor were investigated. The chemosensor can be applied to the quantification of Hg²⁺ with a linear range from 6.6 × 10⁻⁷ to 2.4 × 10⁻⁴ M and a detection limit of 1.3 × 10⁻⁷ M. The experiment results show that the response behavior of compound 1 towards Hg²⁺ is pH independent in neutral conditions (pH 5.0 – 9.0). Most importantly, the fluorescence changes of the chemosensor are remarkably specific for Hg²⁺ in the presence of other metal ions, which meet the selective requirements for practical application. Moreover, the response of the chemosensor toward Hg²⁺ is fast (response time less than 1 min). In addition, the chemosensor has been used for the determination of Hg²⁺ in river water samples with satisfactory results.

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