1. Key Laboratory of Northwest Agricultural Equipment, Ministry of Agriculture and Rural Affairs, Shihezi 832000, China
2. College of Mechanical and Electrical Engineering, Shihezi University, Shihezi 832000, China
3. School of Agricultural Engineering, Jiangsu University, Zhenjiang 212013, China
4. College of Biosystems Engineering and Food Science, Zhejiang University, Hangzhou 310058, China
5. Key Laboratory of Spectroscopy Sensing, Ministry of Agriculture and Rural Affairs, Hangzhou 310058, China
Abstract：Accurate assessment of Hg2+ in farmland soil is significant for constructing high-standard farmland and protecting food security. To solve the problem of low mercury ion concentration and unknown coexisting interference in polluted soil, a method of Hg2+ detection in soil based on electrochemical laser-induced breakdown spectrometry (EC-LIBS) was proposed in this study. First, cyclic voltammetry was used for Hg2+ electrodeposition. Compared with the gold electrode substrate before deposition, it was found that the gold electrode substrate after deposition had obvious emission signals at Hg Ⅰ 435.835 nm, and the surface brightness of the gold nanoparticles increased and the yellowness decreased after deposition. The results show that electrochemical deposition can complete the liquid-solid conversion of mercury ions by forming gold amalgam on the surface of the gold electrode. Secondly, the influence of solvent pH and deposition voltage on the deposition effect was investigated, and the optimal deposition parameters were pH 7.0 and voltage of -400 mV. Finally, the sample LIBS spectral line was obtained, and the Whittaker baseline correction and PLS model were carried out. It was concluded that when Lambda=1.0 and p=0.01, the baseline correction effect was obvious, and the prediction sets RMSEP and MRAEP of the developed PLS model were 5.24 mg·kg-1 and 4.86%, respectively. It shows that EC-LIBS technology combined with the standard model can accurately detect Hg2+ in soil.
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