Sorbent extraction of Pb(II), Cu(II), Ni(II), and Fe(III) ions as 2-(5-bromo-2-pyridylazo)-5-diethylamino-phenol chelates on single-walled carbon nanotube disks prior to their flame atomic absorption spectrometric determinations in animal feeds and natural water samples.

A sorbent extraction procedure for Pb(II), Cu(II), Ni(II), and Fe(III) ions on single-walled carbon nanotube disks has been established. Analyte ions were converted to 2-(5-bromo-2-pyridylazo)-5-diethylamino-phenol chelates, then adsorbed on the disk. Adsorbed chelates were easily desorbed from the disk by using 10 mL 2 M HNO3. The various analytical parameters, including pH and reagent amounts that were effective for the recoveries of the analytes on nanotube disks, were optimized. The influence of matrix ions was also studied. The LOD values based on 3sigma were in the 0.3-4.6 microg/L range. Validation of the proposed SPE procedure was carried out by the determination of analytes in certified reference materials (TMDA-54.4 fortified lake water and HR-1 Humber River sediment). Spiking and recovery experiments for the analyte ions in real samples gave good results. Application of the procedure was illustrated by the determination of analyte contents in some animal feeds and water samples from Turkey.