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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−1range). 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.

A method for speciation of dimethylselenide (DMeSe), dimethyldiselenide (DMeDSe) and diethylselenide (DEtSe) in sediments based on a coupling between a pervaporation module, a preconcentration sorptive trap and a gas chromatograph-mass spectrometer is reported. The coupling is performed through a high pressure injection valve which allows two different operational modes: (a) analysis without preconcentration, in which analytes are directly driven from the pervaporation chamber to the injection port of the chromatograph, and (b) analysis with preconcentration in a trap, in which the analytes from the pervaporation chamber are first trapped on a Tenax minicolumn and then thermally desorbed and driven to the GC. This second approach improves the sensitivity compared to the direct coupling, reaching estimated absolute detection limits lower than 0.6 ng Se for each tested species. The method is applied to the determination of volatile organic selenium species in several sediments collected from different areas in the Southwest of Spain.

Several parameters governing the extraction of metals from iron oxide rich sediments, using sequential extraction schemes were optimized. The mode of shaking, soil/extractant ratio and concentrations of MgCl2 and NH2OH·HCl, for samples collected in the Odiel Marshes Natural Park (SW Spain), were considered. The concentration of NH2OH·HCl deserved particular attention due to the nature of the studied sediments. A 0.4 M concentration of this extractant was needed to avoid readsorption of Cu and As in the samples. In addition, readsorption processes were studied using a candidate to reference material with a high organic matter content that was previously analyzed in an interlaboratory study.

A speciation procedure for arsenobetaine (AsB), arsenite (AsIII), dimethylarsinic acid (DMA), mono-methylarsonic acid (MMA) and arsenate (Asv) based on the couplings HPLC-HG-AFS and HPLC-UV-HG-AFS has been developed and results compared with HPLC-HG-AAS and HPLC-UV-HG-AAS. AFS detection improves the performance of these couplings, being the detection limits about twenty times lower (from 0.06 to 0.14 μg l-1 for AFS against 1.1 to 3.9 μg l-1 for AAS). The linear range extends from 0.25 to 8000 μg l-1 for AFS in contrast to 5 to 500 μg l-1 for AAS. This approach has been applied to the arsenic speciation in biological tissues (certified material TORT-1 and fresh bivalve tissues) in which arsenobetaine was the main species found. Extraction of the species has been carried out using repetitive extractions with methanol and methanol/water (1:1) mixtures being the later more suitable for quantitative recovery.