Abstract

ANDRADE, Charity; CACERES, Ana; LOPEZ, Gabriela  and  MORALES, Ever. Development of an analytical method for the determination of Cr(III) and Cr(VI) species in an aqueous medium. Rev. Int. Contam. Ambient [online]. 2023, vol.39, 54471.  Epub June 05, 2023. ISSN 0188-4999.  https://doi.org/10.20937/rica.54471.

Chromium is present in nature mainly as Cr(III) and Cr(VI) species. Cr(III) is known as an essential trace element, whereas Cr(VI) presents acute toxicity. A chromatographic method (HPLC-ionic) was developed for the determination of both chromium species in contaminated aqueous medium during their treatment by phytoremediation. For this, the previous formation of the anionic complex [Cr(III)-EDTA]- was required. The ionic strength of the mobile phase was evaluated in isocratic mode, while the flow velocity and gradient time were evaluated in gradient mode. Cr(VI) showed a strong interaction with the stationary phase and the determination with 9.0 mM Na2CO3/3.0 mM NaHCO3 of greater ionic strength was adequate, whilst for Cr(III) determination was performed with 2.8 mM Na2CO3/3.4 mM NaHCO3. The use of a concentration gradient allowed for the separation and quantification of both species simultaneously with the appropriate conditions: mobile phase A: 2.8 mM Na2CO3 2-/3.4 mM NaHCO3 with the gradual introduction of B: 9.0 mM Na2CO3/3.0 mM NaHCO3, t = 0.5 min, flow rate of 1.5 mL/min, and sample volume of 50 μL. The use of HPLC-ionic represents an efficient, fast alternative with less environmental impact than conventional techniques with the remarkable advantage of the simultaneous determination of these species.

Keywords : ion chromatography; chromium species; gradient.

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