Determination of trace amounts of Se(IV) by hydride generation atomic fluorescence spectrometry after solid-phase extraction using magnetic multi-walled carbon nanotubes

A sensitive and simple method using magnetic multi-walled carbon nanotubes, as an adsorbent, has been successfully developed for extraction and preconcentration trace amounts of Se(IV) with detection by hydride generation atomic fluorescence spectrometry. The prepared nanoparticles were confirmed by Fourier transform infrared spectra, X-ray diffraction spectrometry, vibrating sample magnetometry, and transmission electron microscopy. These magnetic nanocomposites can be easily dispersed in aqueous samples and retrieved by the application of external magnetic field via a piece of permanent magnet. The main factors affecting the signal intensity such as sample pH value, adsorbent amount, eluent concentration and volume, sample volume, and coexisting ions have been investigated and established. The absorbent could be repeatedly used at least 100 times. The enhancement factor of the proposed method for Se(IV) was 100. The method had a linear calibration plot in the range from 0.05 to 10.0μgL−1 with a standard deviation of 2.3% at 0.5μgL−1 (n=11). The limit of detection was as low as 0.013μgL−1. Accuracy of the method was evaluated by the analysis of water samples and certified reference materials. ► Magnetic multi-walled carbon nanotubes for Se(IV) solid-phase extraction was introduced.► Composition and morphology of the magnetic nanoparticles were characterized.► High sensitivity was further guaranteed by very sensitive HG-AFS.► Satisfactory results were obtained when the assay was applied in the analysis of real samples.