Heavy Metal Sensing

VALUE PROPOSITION

Heavy metal pollution in soils is widespread in the world, resulting from both natural sources and human activities (e.g., mining and smelting, industrial emission, fossil fuel combustion, etc.). Due to their toxicity, bioaccumulation, and environmental persistence, elevated levels of heavy metals in the environment pose major threats to ecosystem health and the safety of food crops grown with contaminated soils and waters. Conventional techniques for heavy metal detection via atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP-AES) or mass spectrometry (ICP-MS) are generally highly sensitive (with part per trillion (ppt) detection limits) and accurate. However, such methods are not practical for in-situ monitoring due to their operational requirements and costly operation. Electrochemical sensors have the advantages of low cost, low power consumption, simplicity, high sensitivity, ease of operation, rapid analysis, portability and applicability for field monitoring of environmental samples. In particular, Anodic Stripping Voltammetry (ASV) has demonstrated the capability to detect heavy metals at sub-part per billion (ppb) level, making it a promising method for field analysis. However, most commonly used electrodes, e.g. liquid Hg, are now avoided due to concerns about their toxicity, and solid electrode materials have been explored as alternatives. There remains a need for improved methods for field monitoring of environmental samples.

DESCRIPTION OF TECHNOLOGY

Among different electrode materials, carbon fiber microelectrodes (CFME) are nontoxic, easy to handle, less expensive, and eco-friendly compared to typical solid metal electrodes such as Bi, Au, and Pt. Additionally, CFME has a renewable/self-cleaning surface due enabling long-term stability of chemical sensing. However, the applications of CFMEs in environmental monitoring have been very limited. This technology uses CFME to detect heavy metals and provides the foundation to develop new sensing technology for in-situ measurements of heavy metals in environments, e.g., soils, plants, and waters. The sensing method involves simple steps that can be realized in the field. The electrode is immersed in a sample solution containing heavy metal ions of interest. A voltage is applied to the electrode, causing the ions to accumulate on the electrode surface. A potential scan is performed to strip the accumulated metal ions from the electrode surface, generating a current response. The magnitude of the current peak is proportional to the concentration of the target metal ion. By analyzing the stripping current, the concentration of heavy metals in the sample can be determined, typically in ppb levels. Carbon fiber electrodes are important as an alternative in ASV due to their unique properties. These electrodes have a high surface area, excellent electrical conductivity, and superior mechanical strength. These qualities make them useful for heavy metal detection in ASV.

BENEFITS