ON-LINE SOLID PHASE EXTRACTION OF NI AND PB USING CARBON NANOTUBES AND MODIFIED CARBON NANOTUBES COUPLED TO ETAAS?

MARIANELA SAVIO; PABLO H. PACHECO; LUIS D. MARTINEZ; PATRICIA SMICHOWSKI; RAÚL A. GIL

Simposio; Eleventh Rio Symposium on Atomic Spectrometry; 2010

A study was undertaken in order to develop a method to determine Ni and Pb at ultra-trace levels by electrothermal atomization atomic absorption spectroscopy (ETAAS). For this, a column-solid phase strategy was evaluated using three kinds of nanomaterials i.e. carbon nanotubes (CNT), oxidized carbon nanotubes (o-CNT) and alanine immobilized on carbon nanotubes (ala-CNT). The overall methodology included the on-line coupling of the solid phase extraction with the sample injection step into the graphite furnace atomizer. The solid phase extraction was performed in a conical minicolumn that served as sorbent holder. After loading the analytes (a fixed volume) they were eluted with a discrete volume (50 µL) of nitric acid and placed directly into the platform of a L?Vov tube. After that, each analyte was determined individually following the temperature program recommended by the instrument manufacturer. Both Ni and Pb showed differential behavior when the effect of the pH was evaluated with each individual sorbent. It was also noted that the o-CNT sorbent is the one that demonstrated the highest capacity and linearity for both analytes when compared with CNT and ala-CNT. The analytical performance was evaluated for the three kinds of sorbents in order to establish the best conditions regarding to sensitivity, reproducibility (precision) and accuracy. After optimization, the method that involved the use of o-CNT associated to an on-line preconcentration is proposed to Ni and Pb.