Low-Noise Potentiostat Circuit for Electrochemical Detection of Heavy Metals or Metalloids

Detection and quantification of water contaminants, such as arsenic (As), mercury (Hg), and copper (Cu), require highly sensitive and inexpensive portable devices. In this article, a low-noise portable potentiostat circuit is proposed for the simultaneous detection of As(III), Hg(II), and Cu(II) at the ppb level. This design neither requires external devices such as personal computer (PCs) or smartphones nor any dedicated software for data acquisition. The overall circuit’s noise is analyzed to reduce the noise so that measurement precision improves. The proposed circuit has a noise floor of 1.6 nV/ $\sqrt {\mathrm {Hz}}$ @ 10 kHz and the simulated root-mean-square (RMS) noise is 900 nV. The practical application of the designed circuit for the detection and quantification of As(III), Hg(II), and Cu(II) is demonstrated using a gold (Au)-coated electrode. The reliability of the measurement is verified by comparing it with commercial AUTOLAB potentiostat. The results indicate that the proposed portable system is reliable, and low concentration (in ppb) of As(III), Hg(II), and Cu(II) in water can be measured quantitatively.

I. Introduction

Arsenic and mercury are two of the most harmful elements found in the Earth’s crust and groundwater. However, improper waste management, metal industries, fertilizers, pesticides, and other factors are the principal causes of water contamination. The toxic water contaminants, such as As(III), Hg(II), and Cu(II), enter into the food chain directly or indirectly and seriously affect human health. For instance, drinking water contaminated with As(III) may lead to skin lesions, lung cancer, bladder cancer, and various other illnesses [1], [2]. High exposure to Hg(II), on the other hand, causes kidney and respiratory failure, gastrointestinal and nervous system damage, and impairment of speech, hearing, and functioning ability [3], [4]. According to the World Health Organization (WHO), drinking water with greater than ten ppb of As(III) and two ppb of Hg(II) is not safe. The selective detection of these water contaminants necessitates the use of a highly sensitive portable system.