IMMOBILIZED CYANOBACTERIA FOR ONLINE TRACE-METAL ENRICHMENT BY FLOW-INJECTION ATOMIC-ABSORPTION SPECTROMETRY

Cyanobacteria (Spirulina platensis) immobilized on controlled pore glass preconcentrate Cu(II), Zn(II), Cd(II), Pb(II), and Fe(III) from aqueous solution with high efficiency as ascertained using an on-line flow injection atomic absorption spectrometry system. The degree of metal binding depends on the pH of the solution. Quantitative retention of copper, zinc, and cadmium occurred at a wide range of pH values, while the retention for lead and iron was pH-dependent. The latter metals were adsorbed strongly only at pH 6 and 7, respectively. The breakthrough capacity was determined from the breakthrough curve, with values of 0.0035, 0.0008, 0.0011, 0.0028, and 0.0017 ng/mL for Cu, Zn, Cd, Pb, and Fe, respectively, being obtained. The analysis of a certified reference sample, sewage sludge of domestic origin (BCR No. 144), for cadmium and copper with a high accuracy ensures the feasibility of this technique for environmental analysis.