Electroanalytical metal sensor with built-in oxygen filter

Highlights: • Electrochemical oxygen filter is combined with a metal sensing system. • Stripping chronopotentiometry is accordingly adapted for the optimal filter use. • Comparable limits of detection are obtained with O₂ filter and classical N₂ purging. • Total metal concentration is quantified for different matrix solutions. A rapid and reliable oxygen elimination system was evaluated here for the electroanalytical study of metals. Dissolved oxygen was removed locally in the vicinity of a sensor by the means of electrochemical oxygen filter constructed from platinum grids. Three metals (Cd, Pb, and Zn) were determined by stripping chronopotentiometry (SCP) at a mercury film screen-printed electrode. Limits of detection of metals were in the nanomolar range under optimized experimental conditions. The electrochemical device was also tested for metal quantification in simple electrolyte solutions and in a natural water matrix. The proposed combination of oxygen elimination system with the metal sensor completely removes the need to purge the sample before SCP measurement. This makes the determination of metals by SCP faster, portable and more suited for on-field applications.