A novel Fe3O4-polymeric ionic liquid magnetic nanocomposite for O.Hy.1 efficient preconcentration and speciation analysis of inorganic tellurium in environmental samples by flow injection-hydride generation atomic fluorescence spectrometry

Abstract

A novel magnetic polymeric ionic liquid (PIL) nanocomposite was synthetized and successfully applied for the preconcentration and speciation analysis of Te in different environmental samples. The nanocomposite was prepared by an approach based on the Radziszewski reaction, which is a simple and straightforward procedure to obtain imidazolium-type PILs under mild conditions, in the presence of aminofunctionalized magnetic Fe3O4 nanoparticles.1 A complete characterization of the nanocomposite by different techniques such as: infrared spectroscopy, zeta potential and X-ray diffraction, among others, was performed. The synthesized PIL material was applied for the preconcentration and speciation analysis of Te -an element with increasing applications in several fields-2 in waters, soils and sediments. pH was found to be a crucial parameter for the selective extraction of Te(IV) and Te(VI) species, being Te(IV) selectively extracted at pH values below 1.5. The effect of other parameters such as the type and concentration of complexing agents, sample volume, mass of extractant, extraction and phase separation time and type of eluent were also carefully studied, with the aim of maximizing the efficiency and selectivity of the method. A 100% retention efficiency was obtained under optimized conditions, even with sample volumes as high as 25 mL. Additionally, variables related to the determination of Te by hydride generation atomic fluorescence spectrometry (HG-AFS) were studied. To maximize the sensitivity of the measurements, an external flow-injection hydride generation system was adapted to the AF spectrometer. This resulted in a low volume hydride generation system that allowed the efficient generation of the Te hydride from a reduced extract volume (400 µL), yielding an excellent sensitivity and a limit of detection of 1.9 ng L-1 for Te(IV) and of 3.7 ng L-1 for Te(VI). Finally, the optimized procedure was successfully applied for the determination of Te(IV) and Te(VI) in water, soil and sediment samples, with recovery values ranging from 95.4% to 105% for Te(IV) and from 90.0% to 107% for Te(VI).