Use of Saccharomyces cerevisiae in flow injection atomic absorption spectrometry for trace metal preconcentration.

Abstract

The yeast Saccharomyces cerevisiae was covalently immobilized on controlled pore glass (CPG) using a modified method of enzyme immobilization. This species was packed in a mini-column and incorporated in a flow injection manifold system for trace determination of some metals prior to quantification with atomic absorption spectrometry (AAS). A number of investigations on the ability of the microorganism to remove metal ions from solution have shown that different metal ions bind to the cell wall of yeast. We have observed that the pH-dependence behavior is different for Pb(II) and Fe(III) compared to the other metal ions. Between pH 6.0 and 7.5 a variety of metal ions bind strongly to the cell surface. All the metal ions tested were deabsorbed by lowering the pH to < 2.0. Samples of 5 mL of Cd(II), Zn(II), Cu(II), Pb(II), and Fe(III) were preconcentrated to give detection limits of 0.2, 0.1, 0.7, 8.0, and 0.6 ng/mL, respectively. The analysis of real sample reference material showed a good agreement with the certified values for cadmium and copper.