Smartphone-based three-channel ratiometric fluorescent device and application in filed analysis of Hg2+, Fe3+ and Cu2+ in water samples

Abstract

Determination of metal ions in water samples, especially harmful heavy metal like mercury or essential elements like iron and copper, is an important work in environmental monitoring. Herein, we report a smartphone-based three-channel ratiometric fluorescence device for simultaneous determination of Hg 2+ , Fe 3+ and Cu 2+ in environmental samples on site. It was based on the fluorescence quench mechanism of Hg 2+ , Fe 3+ and Cu 2+ to three kinds of doped carbon quantum dots, which were prepared by pyrolysis methods using ammonium citrate, citric acid + 1,10-phenanthroline, and EDTA + thiourea as initial materials, respectively. By using a multivariate calibration method, the mutual interference among Hg 2+ , Fe 3+ and Cu 2+ can be corrected. Under the optimized conditions, the limits of detection for Hg 2+ , Cu 2+ and Fe 3+ are 3, 0.5, and 30 nM, respectively. The proposed device offers the advantage of portability, sensitivity and reliability for field analysis.