Ultra-trace tellurium preconcentration and speciation analysis in environmental samples with a novel magnetic polymeric ionic liquid nanocomposite and magnetic dispersive micro-solid phase extraction with flow-injection hydride generation atomic fluorescence spectrometry detection

A highly efficient magnetic dispersive micro-solid phase extraction (M-D-mu SPE) method was developed for Te preconcentration and speciation analysis in different environmental samples. A novel magnetic polymeric ionic liquid nanocomposite synthesized based on the Radziszewski reaction was applied for the selective retention of Te(IV) species, followed by elution with 5 mol L-1 HCl and determination by flow-injection hydride generation atomic fluorescence spectrometry. Te(VI) was selectively determined by difference between total Te and Te(IV) after a pre-reduction step. Studies on the sorption capacity of the nanocomposite were performed, while several parameters concerning the retention, separation and elution were optimized. A 100% retention efficiency and a sensitivity enhancement factor of 67 were achieved. Limits of detection of 1.9 ng L-1 and 3.7 ng L-1, and standard deviations of 4.3% and 5.1% were obtained for Te(IV) and Te(VI). A gas-liquid separator with a low dead volume was used for reduced dispersion of the flow injection signals and additional sensitivity enhancement. Finally, the feasibility of the proposed M-D-mu SPE method for Te speciation was demonstrated by the analysis of several environmental samples, such as tap, rain, river and underground waters, soils and sediments, with excellent recovery results in spiked samples.