Arsenic and antimony speciation analysis in copper electrolyte by liquid chromatography coupled to hydride generation atomic fluorescence spectrometry (HPLC-HG-AFS)

Abstract

A novel method based on high performance liquid chromatography (HPLC) coupled to hydride generation-atomic fluorescence spectrometry (HG-AFS) is proposed for the determination of arsenic and antimony redox couples (As(III), As(V), Sb(III) and Sb(V)) in copper electrolyte samples, which are characterized by extreme acidity and high metallic content (Cu and Ni in the g L⁻¹ range). The determination of the oxidation states of As and Sb in sulfuric acid based electrolyte is of critical importance as these elements can form slimes that affect copper quality. The proposed speciation method was successfully applied to industrial electrolyte samples, indicating that As(V) and Sb(III) were the predominant species in the electrolyte. The results were validated by comparison with total arsenic and antimony content determined with ICP-OES. The stability of arsenic and antimony species in the samples prior to analysis was also studied during a period of 28 days considering aqueous dilution, acidification with HCl and different storage temperature (4 °C, 25 °C or 65 °C). The dilution and the acidification with HCl caused partial oxidation of Sb(III) to Sb(V), while the As species were not affected. Undiluted copper electrolyte samples showed stability periods of 14 and 28 days for Sb and As, respectively, independently of the storage temperature.