The determination of REE by ICP OES often requires sample
pretreatment steps in order to overcome spectral interferences from
major elements present in the sample, as well as for improving
detectability of analytes whose concentration are generally below
typical ICP OES methods detection limits (e.g., 5–20 μg L−1) [11].
Under these premises, the proposed procedure based on Ce, La and Nd
preconcentration by using CA beads for further determination by ICP
OES was applied for the analysis of groundwater samples. The
fragments of emission spectrum showing the Ce (II) 456.236, La (II)
379.478 and Nd (II) 430.358 nm selected emission lines demonstrate
the typical signal enhancement attained by the proposed approach
(Fig. 2). There was a significant improvement in the signal-to-noise
ratio (SNR) of Ce, La and Nd measurements in the preconcentrated (i.
e., 20 times enriched) groundwater samples in comparison to those
from samples analyzed directly, which increased from ca. unit (i.e., the
condition where analyte emission signal is indistinguishable from
background) to 19, 88 and 31, respectively. The enhancement in
sensitivities for La and Nd were much more evident than for Ce.