PRECONCENTRATION AND DETERMINATION OF SOME LANTHANIDE ELEMENTS WITH IMMOBILIZED BACTERIA BY FLOW-INJECTION INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY

The on-line combination of flow injection column preconcentration with sequential inductively coupled plasma atomic emission spectrometry is shown to provide an enrichment factor of 36 for La3+, 34 for Ce3+ and 51 for Nd3+, at 1 mu g ml(-1) for 5 ml of sample. The significant imp rovement in the (3 s) detection limit by preconcentration compared wit h that without preconcentration demonstrates the efficiency of preconc entration with the bacterium Spirulina platensis immobilized on contro lled-pore glass. Recovery of all the lanthanide cations is quantitativ e and the capacity was calculated. Practical application bf the method was demonstrated by the determination of La3+ and Nd3+ impurities in a cerium(III) nitrate reagent. Adsorption isotherm studies were used t o describe the mechanisms and the nature of the column binding sites. Isotherm plots showed a Langmuirian shape for La3+ and an anti-Langmui rian shape for Ce3+ and Nd3+. Equilibrium constants were also calculat ed.