RESUMO
A method for the determination of Ni(II) using ion-transfer to a hydroxide medium has been developed by the sequential injection-electrochemical analysis (SIECA), a combination between an automated flow-based analysis and electrochemical techniques with a homemade screen-printed carbon electrode (SPCE). A sample/standard solution was introduced into an electrochemical flow cell where the Ni(II) in the solution was electrochemically reduced and accumulated on the SPCE. The accumulated Ni was then oxidized to Ni(II) in a hydroxide medium, which led to the formation of nickel hydroxide (Ni(OH)2) and nickel oxyhydroxide (NiOOH) on the SPCE. The electrochemical response associated with Ni(OH)2 and NiOOH was subsequently determined by square-wave voltammetry to account for Ni(II). Under optimal conditions, the proposed method provides a low detection limit of 0.02mgmL-1. This method was further applied to determine the Ni(II) content of standard-spiked mineral water samples with satisfactory results.
