A Portable Electrochemical System for the On-Site Detection of Heavy Metals in Farmland Soil Based on Electrochemical Sensors

In this paper, a portable electrochemical system for the on-site detection of heavy metals (HMs) in farmland soil is developed, characterized, and evaluated. The system has a three-electrode configuration and includes a signal acquisition and processing device and a computer, which integrates a microcontroller-based potentiostat to implement square-wave anodic stripping voltammetry at a bismuth-film-modified glassy carbon electrode. In addition, three analysis methods, namely, the standard addition method, the bivariate regression model, and double-stripping voltammetry, were integrated into this system for the on-site detection of HMs to meet different analysis requirements. One unique characteristic of the system is its custom software, which enables calculations based on all three analysis methods. Moreover, stripping peak currents and background currents can be identified and acquired automatically by two of the developed algorithms. The system was assessed by applying it to detect Pb(II) and Cd(II) in an acetate buffer solution and acetic acid soil extracts. The interference of Cu(II) can be inhibited by adding 0.1-mM ferrocyanide to the real sample exacts by complexation. The results indicate that the system was sensitive, effective, and reliable and has broad application prospects in the field of on-site analysis. In addition, the system can be used by non-specialist personnel.