An Electrochemical Robotic System for Routine Cathodic Adsorptive Stripping Analysis of Ni²⁺ Ion Release from Corroding NiTi Shape Memory Alloys

Abstract

Abstract Cathodic adsorptive stripping voltammetry (AdSV) as highly sensitive and selective method for quantifying trace amounts of dissolved Ni 2+ ‐ions has been integrated into an electrochemical robotic device using the wells of microtiter plates as low‐volume electrochemical cells. A three‐electrode assembly integrating a Bismuth film‐modified glassy carbon electrode as working electrode and a glass capillary for delivering Ni 2+ standard solution in conjunction with an adapted software allowed multiple AdSV measuring cycles to be performed one after the other in the individual compartments of a 24‐well microtiter plate. Of advantage for the automation was the possibility of an in‐well electrochemical removal of used and a replating of fresh Bi films in between distinct measuring cycles. With optimized parameters for the accumulation of the complex between Ni 2+ ‐ions and dimethylglyoxime onto the surface of the Bi film electrode and the subsequent stripping procedure, automated adsorptive stripping voltammetry in the established system offered a linear dynamic range of up to 170 nM, a sensitivity of 12 nA/nM Ni 2+ and a limit of of detection of 2.1 nM ( N =16) for the detection of trace levels of Ni 2+ ‐ions. Automated AdSV certainly is of convenience for studying larger number of samples due to the high‐throughput capability of the robotic apparatus. As example, the automatic quantification of Ni 2+ ‐ion release from electropolished surfaces of NiTi shape memory alloys during corrosion in NaCl solutions is described.