Šíma J., Holcová V., Dušek J.: Electrochemical speciation of iron oxidation states in wastewater treated using a constructed wetland. Ekológia (Bratislava), Vol. 29, No. 3, p. 326-337, 2010. Differential pulse voltammetry (DPV) was tested for the determination of iron in wastewater samples from a constructed wetland used for improving water quality. The concentration of total iron was determined in an oxalate working electrolyte. The electrode process was electrochemically irreversible in a

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... um pyrophosphate working electrolyte and the iron oxidation states were separated. Iron concentrations determined using DPV were compared with results attained for a traditional spectrophotometric determination with 1,10-phenanthroline. Attained limits of detection were 0.03 mg l -1 for the voltammetric determination of total iron and 0.02 mg l -1 for Fe II and 0.01 mg l -1 for the spectrometric determination. DPV determination of iron expands the possibilities of electrochemical methods for wastewater analysis. The content of individual iron oxidation states serves as an indicator of constructed wetland aeration and redox properties.