Interference Analysis for Electrochemical Heavy Metal Ion Sensors in Terms of Stripping Current, Barrier Width and Adsorption

Abstract

Understanding interference effects toward the detection of target analytes is important. In an earlier work we reported for the first time the use of the barrier width (BW) technique using a single concentration of the target analyte (Cd2+) to characterize the interference effects of various heavy metal ions with lesser number of experiments as compared to the conventional stripping current based peak reduction (PR) technique, and developed a scale of interference. There is a need to benchmark the BW technique with the PR technique for its claim of usage and to develop a scale of interference with a higher resolution. In this work, utilizing the BW technique we report the analysis based on Cd2+ concentrations spanning two orders of magnitude and interfering ions (Al3+ (less interfering), Fe2+ (moderately interfering) and Cr6+ (heavily interfering)) also spanning two orders of magnitude. The sensitivity parameters were benchmarked thereby validating BW technique. Adsorption isotherms were constructed for each case and −ΔGads values were evaluated. A correlation obtained from the sensitivity parameters from the BW and PR techniques and −ΔGads yielded an interference scale with a resolution higher than that of the scale obtained by the PR technique or the BW technique.