Determination of SbIII and SbV in water samples based on highly selective solid-phase extraction with polyvinyl imidazole

Title : Determination of SbIII and SbV in water samples based on highly selective solid-phase extraction with polyvinyl imidazole

Abstract:

Antimony is a chemical element that occurs in the environment as a result of natural and anthropogenic processes and its biogeochemical cycle is nowadays sufficiently characterized. Toxicological profiles and bioaccumulative properties of particular Sb species are well known – the inorganic chemical forms are much more harmful than organic species, especially the lower oxidation state Sb^III. In this sense, reliable knowledge about Sb speciation is essential taking into account significant differences between toxicity and bioavailability of trivalent and pentavalent forms.

This work is focused on the preparation of vinylimidazole-based polymeric material and its further application as a sorbent for non-chromatographic speciation analysis of inorganic antimony in water samples. The polymer was synthesized by radical polymerization of vinylimidazole as a functional monomer, acetonitrile as a solvent, trimethylolpropane trimethacrylate as a cross-linking agent and 2,2′-azo-bis-isobutyronitrile as an initiator. Extraction efficiency and selectivity of the prepared material toward inorganic chemical species of antimony (Sb^III and Sb^V) were studied by batch method. Several parameters such as pH of the aqueous media, amount of the polymeric sorbent, time of sorption, type and concentration of the eluent solution were investigated in order to define the optimal chemical conditions for selective separation and enrichment of both Sb^III and Sb^V. Inorganic Sb species at trace levels were separated by quantitative retention of Sb^V at pH 5-6 for 25 minutes followed by elution with 0.1 M citric acid and ICP-MS measurement. The supernatant solution, containing Sb^III, was removed and treated with conc. HCl in order to convert Sb^III in negatively charged chloride complex and then 100 mg of sorbent material were added. Quantitative sorption was achieved for 15 min and after that, elution of Sb^III was carried out with 0.1 M tartaric acid for 20 min followed by measurement with ICP-MS. Additionally, total concentration of antimony can be determined in a parallel sample after preliminary conversion of Sb^III to Sb^V by oxidation with H₂O₂ and subsequent extraction according to the procedure described for the retention of Sb^V. Thus a simple analytical scheme for speciation and determination of inorgaic Sb in natural and bottled waters based on two sequential extraction steps was developed.

Acknowledgement: The authors gratefully acknowledge the financial support provided by the Bulgarian National Scientific Foundation (Grant DN 19/10 SmartSpeciation).

Audience take-away: 

• Synthesis and application of vinylimidazole-based polymeric sorbent
• Non-chromatographic approach for speciation analysis of antimony
• Fast and reliable analytical procedure for determination of Sb^III and Sb^V in water samples

Biography:

Dr. Yordanova studied Chemistry at the Sofia University, Bulgaria and graduated as MS in 2010. She then joined the research group of Prof. Karadjova at the Department of Analytical Chemistry, Faculty of Chemistry and Pharmacy, Sofia University St. Kliment Ohridski. She received her PhD degree in 2014 at the same institution. After defense of her PhD thesis, she obtained the position of Chief Assistant Professor at the same department. She has published 12 research articles and 1 book chapter.