Analytical note On-line determination of Sb(III) and total Sb using baker's yeast immobilized on polyurethane foam and hydride generation inductively coupled plasma optical emission spectrometry Amauri A. Menegário a, ⁎ , Ariovaldo José Silva a , Eloísa Pozzi b , Steven F. Durrant c , Cassio H. Abreu Jr. d a Centro de Estudos Ambientais, Universidade Estadual Paulista, Av. 24-A, 1515, CEP 13506-900, Rio Claro, SP, Brazil b Escola de Engenharia de São Carlos, Universidade de São Paulo, Av. Trabalhador Sãocarlense 400, CEP 13566-590, São Carlos, SP, Brazil c Laboratório de Plasmas Tecnológicos, Campus Experimental de Sorocaba, Universidade Estadual Paulista- UNESP, Avenida Três de Março 511, CEP 18087-180, Sorocaba, SP, Brazil d Centro de Energia Nuclear na Agricultura, Universidade de São Paulo, Av. Centenário, 303, Caixa Postal 96, CEP 13400-970, Piracicaba, SP, Brazil Received 19 January 2006; accepted 15 September 2006 Abstract The yeast Saccharomyces cerevisiae was immobilized in cubes of polyurethane foam and the ability of this immobilized material to separate Sb(III) and Sb(V) was investigated. A method based on sequential determination of total Sb (after on-line reduction of Sb(V) to Sb(III) with thiourea) and Sb(III) (after on-line solid–liquid phase extraction) by hydride generation inductively coupled plasma optical emission spectrometry is proposed. A flow system assembled with solenoid valves was used to manage all stages of the process. The effects of pH, sample loading and elution flow rates on solid–liquid phase extraction of Sb(III) were evaluated. Also, the parameters related to on- line pre-reduction (reaction coil and flow rates) were optimized. Detection limits of 0.8 and 0.15 μgL - 1 were obtained for total Sb and Sb (III), respectively. The proposed method was applied to the analysis of river water and effluent samples. The results obtained for the determination of total Sb were in agreement with expected values, including the river water Standard Reference Material 1640 certified by the National Institute of Standards and Technology (NIST). Recoveries of Sb(III) and Sb(V) in spiked samples were between 81±19 and 111± 15% when 120 s of sample loading were used. © 2006 Elsevier B.V. All rights reserved. Keywords: Sb(III); Sb(V); ICP OES; Saccharomyces cerevisiae; Speciation analysis 1. Introduction Antimony is a potentially toxic element and its compounds are considered as pollutants of priority interest by environmen- tal agencies. In environmental samples, antimony is usually present mainly as inorganic Sb(III) and Sb(V) [1,2], which have different toxicities: trivalent forms are ten times more toxic than pentavalent species. Typical concentrations of total dissolved antimony in non-polluted waters range from ng L - 1 to μgL - 1 [1]. Thus, methods for determination of antimony species at trace levels are fundamental for environmental studies. The coupling of hydride generation (HG) with atomic spectrometry techniques provides powerful methods for determination of antimony at trace levels. HG can be also used for selective generation of antimony species by exploiting the pH-dependence of stibine generation from Sb(III) and Sb(V) [3–8]. The generation of stibine from Sb(III) and Sb(V) depends on several parameters but, generally, Sb(III) is selectively generated at a pH greater than 2 [9]. Although this approach is simple and popular, interferences from transition metals in the generation of stibine from Sb(III) can be uncontrollable at low acid concentration [9]. Other approaches Spectrochimica Acta Part B 61 (2006) 1074 – 1079 www.elsevier.com/locate/sab ⁎ Corresponding author. Tel./fax: +55 1935340122. E-mail address: amenega@rc.unesp.br (A.A. Menegário). 0584-8547/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.sab.2006.09.008