Determination of Cadmium by Magnetic Multiwalled Carbon Nanotube Flow Injection Preconcentration and Graphite Furnace Atomic Absorption Spectrometry

Magnetic multiwalled carbon nanotubes were incorporated on iron oxide nanoparticles and used for the magnetic solid-phase extraction of cadmium prior to quantification by graphite furnace atomic absorption spectrometry with flow injection analysis. Cadmium was retained in a microcolumn filled with the magnetic multiwalled carbon nanotubes and quantitatively eluted with nitric acid. The major parameters affecting the extraction efficiency were investigated, including the sample pH, sample flow rate, sorbent amount, sample volume, eluent concentration, and eluent volume. The optimum conditions were pH 7.0, a flow rate of 16 mu L s(-1), 10mg of magnetic nanoparticles, a sample volume of 10mL, an eluent concentration of 0.1mol L-1, and an eluent volume of 1mL. The linear dynamic range was from 0.01 to 10 mu g L-1, with a relative standard deviation of 2.3% at 1.0 mu g L-1. The limit of detection was 1.2ng L-1 and the preconcentration factor was approximately 160. The accuracy of the method was evaluated by the analysis of urine, water, and certified reference materials.