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 µg ml–1 for 5 ml of sample. The significant improvement in the (3 s) detection limit by preconcentration compared with that without preconcentration demonstrates the efficiency of preconcentration with the bacterium Spirulina platensis immobilized on controlled-pore glass. Recovery of all the lanthanide cations is quantitative and the capacity was calculated. Practical application of the method was demonstrated by the determination of La3+ and Nd3+ impurities in a cerium (III) nitrate reagent. Adsorption isotherm studies were used to describe the mechanisms and the nature of the column binding sites. Isotherm plots showed a Langmuirian shape for La3+ and an anti-Langmuirian shape for Ce3+ and Nd3+. Equilibrium constants were also calculated.