Electrochemical Sensors for Heavy Metal Ion Detection: Principles, Advances, and Challenges

The continuous discharge of heavy metal ions resulting from intense industrial activity into the environment poses risks to all life on Earth (high toxicity and bioaccumulation). As a consequence, it is critical to develop analytical methods and sensors capable of detecting traces of heavy metals in a fast, accurate, and reliable manner. The requisites of low cost and simple instrumentation make electrochemical sensors promising alternatives, offering advantages such as high sensitivity/selectivity, as well as in situ and real‐time monitoring through the mapping of redox processes that are combined to achieve lower detection limits (LODs) by exploring electrode modification‐based strategies with nanomaterials that enhance selectivity through the use of biosensors and biopolymers by the incorporation of specific groups by functionalization in portable devices. This review discusses the main challenges in electrochemical techniques and the optimization of sensing elements, including matrix interferences, stability, reproducibility, sensor regeneration for multiple uses, and analytical standardization, for the detection of heavy metal ions in real liquid samples, instead of standard and pH‐controlled electrolytes.