ICP-MS DETERMINATION OF RARE EARTH ELEMENTS IN AIRBORNE PARTICUALTE MATTER COLLECTED IN BUENOS AIRES, ARGENTINA

MARIANELA SAVIO; RAÚL A. GIL; ROBERTO A. OLSINA; DARÍO GOMEZ; PATRICIA SMICHOWSKI

Simposio; 12th Rio Symposium on Atomic Spectrometry (2012); 2012

Air pollution in urban areas arises from natural and anthropogenic sources. Studies on the content of rear earth elements (REEs) in airborne particles has far less been a topic of research in comparison with most studies devoted to the determination of major, minor and trace elements in atmospheric aerosols. However, for their world-wide use (electronics, superconductors, fabrication of lasers, nuclear batteries, special alloys, ceramic capacitors, colorant in glasses and enamels, fluorescent lamps, pharmaceutical, fertilizers, etc) their contribution to airborne particulate matter (APM) has increasing in the last decades destabilizing the natural balance of the ecosystem as a hidden trouble. To study their unknown effects on humans, it is of prime importance to develop sensitive and selective methodologies for their determination in relevant environmental matrices. In this context and for the scarcity of studies on REEs in APM an investigation was undertaken for the quantification of Ce, Dy, Er, Ga, Eu, Ho, La, Lu, Nd, Pr, Sm, Tb, Tm and Yb in Buenos Aires PM10 airborne particles. Ten samples were collected on ash-free glass-fiber filters during a short monitoring campaign carried out in 2011. Once in the laboratory, filters were cut in strips and digested using a mixture of aqua regia and HF (5:1). Then, REEs were quantified in the solutions by ICP-MS (Perkin-Elmer SCIEX, ELAN DRC-e). Blank samples were prepared in the same way as the samples. Concentration of analytes in samples were obtained by subtracting blank values from the determined values. For checking accuracy, aliquots two CRMs namely, San Joaquin Soil (NIST 2709) and Urban particulate matter (NIST 1648) were subject to the same treatment that the samples and included in the over-all analytical process. Limits of detection (in ng m-3) varied from 0.01 (Eu) to 2.43 (La) and precision was in all cases better than 9.1 %. Mean concentrations of REEs in APM resulted to be (in ng m-3): 0.01 (Eu) < 0.02 (Er) < 0.04 (Yb) < 0.05 (Dy) < 0.07 (Gd, Sm) < 0.11 (Pr) < 0.45 (Nd) < 1.45 (Ce) < 2.43 (Ls). Four elements were not detected in the analyzed samples: Ho (< 0.13 ng m-3), Lu (< 0.12 ng m-3), Tb (0.15 ng m-3) and Tm (0.11 ng m-3). This preliminary study was mainly focused to develop analytical methodology for REEs determination in APM by ICP-MS. New monitoring campaigns considering more points for sample collection will allow us to calculate the ratios La:Ce and La:Sm that will be used as tracers for the origin of the REEs.