Speciation of Inorganic Antimony in Natural Waters by Electrothermal Atomic Absorption Spectrometry after Selective Separation and Preconcentration of Antimony(III) with Cloud Point Extraction

Ingrid Hagarová*, Jana Kubová, Peter Matúš and Marek Bujdoš

Comenius University in Bratislava, Faculty of Natural Sciences, Geological Institute, Mlynská dolina G, 842 15 Bratislava 4, Slovak Republic
* Corresponding author: E-mail: hagarova@fns.uniba.sk

Abstract
In this work, cloud point extraction (CPE) was applied as a separation/preconcentration step for electrothermal atomic absorption spectrometric (ETAAS) determination of ultratrace Sb(III) in natural water samples. After complexation with ammonium pyrrolidine dithiocarbamate (APDC) in mildly acidic medium, the analyte was quantitatively extracted to the phase rich in the non-ionic surfactant octyl phenoxy polyethoxy ethanol (Triton X-114) after centrifugation. Then the surfactant-rich phase was diluted by 0.20 mol L^–1 HNO₃ in methanol and the concentrated analyte was introduced into ETAAS. Potential factors affecting the CPE separation/preconcentration of Sb(III) were investigated in detail. Under optimal conditions, the relative standard deviation (RSD) for ten replicate measurements at 0.40 µg L^–1 Sb(III) level was 6.5% and the enrichment factor for this determination was 28. The linear concentration range was from 0.10 to 3.50 µg L^–1 Sb(III). The detection limit of 0.03 µg L^–1 Sb(III) was achieved. The optimized method was applied to the determination of Sb(III) in well and lake water samples.

Keywords: Antimony, speciation analysis, cloud point extraction, electrothermal atomic absorption spectrometry, water analysis