Flame atomic absorption spectroscopy determination of zinc after its preconcentration with modified multi walled carbon nanotubes

The present research reports on the application of modified multi walled carbon nanotubes (MMWCNTs) as a new, easily prepared and stable solid sorbent for the column preconcentration of ultra trace amounts of Zn(II) in aqueous solution. Multi walled carbon nanotubes (MWCNTs) were oxidized and modified, and were then used as a solid phase for the column preconcentration of zinc ion. Factors influencing the sorption and desorption of Zn(II) were investigated. Elution was carried out with the 0.5 mol L–1 HNO3. The amount of eluted Zn(II) was measured using flame atomic absorption spectrometry. The effects of the experimental parameters, including the sample pH, sample flow rate, eluent flow rate and eluent concentration, were investigated. The proposed method permitted a large enrichment factor (about 250). About 0.2 ng of zinc can be concentrated in a column from 1000 mL of aqueous sample, where its concentration is as low as 0.2 pg mL–1. Eight replicate determinations of 1.0 ng mL–1 of zinc gave a mean absorbance of 0.160 with a relative standard deviation of 1.20%. The sensitivity for 1% absorption was 16.5 pg mL–1.

Keywords:

Multi walled carbon nanotubes , Zinc determination , FAAS