Heat-treated Saccharomyces cerevisiae for antimony speciation and antimony(III)preconcentration in water samples

摘要

An analytical method was developed for antimony speciation and antimony(III)preconcentration in water samples.The method is based on the selective retention of Sb(III)by modified Saccharomyces cerevisiae in the presence of Sb(V).Heat,caustic and solvent pretreatments of the biomass were investigated to improve the kinetics and thermodynamics of Sb(III)uptake process at room temperature.Heating for 30min at 80 °C was defined as the optimal treatment.Antimony accumulation by the cells was independent of pH(5-10)and ionic strength(0.01-0.1 molL~(-1)).140 mg of yeast and 2h of contact were necessary to ensure quantitative sequestration of Sb(III)up to 750mu gL~(-1).In these conditions,Sb(V)was not retained.Sb(V)was quantified in sorption supernatant by inductively coupled plasma mass spectrometry(ICbeta-MS)or inductively coupled plasma optical emission spectrometry(ICP-OES).Sb(III)was determined after elution with 40mmolL~(-1)thioglycolic acid at pH 10.A preconcentration factor close to nine was achieved for Sb(III)when 100 mL of sample was processed.After preconcentration,the detection limits for Sb(III)and Sb(V)were 2 and 5ngL~(-1),respectively,using ICbeta-MS,7 and 0.9 mu g L~(-1)using ICbeta-OES.The proposed method was successfully applied to the determination of Sb(III)and Sb(V)in spiked river and mineral water samples.The relative standard deviations(n=3)were in the 2-5% range at the tenth mu gL~(-1)level and less than 10% at the lowest Sb(III)and Sb(V)tested concentration(0.1 mu gL~(-1)).Corrected recoveries were in all cases close to 100%.