Separation and preconcentration of inorganic selenium species in water samples with a novel nanosilica-ionic liquid hybrid material and etaas detection

LLAVER, MAURICIO; WUILLOUD, RODOLFO G.

Vitoria

Simposio; 14th RIO SYMPOSIUM ON ATOMIC SPECTROMETRY; 2017

Universidade do Espírito Santo (UFES)

The functionalization of porous silica nanoparticles with the ionic liquid (IL) 3-methyl-1-dodecylimidazolium bromide and its application as a sorption material for the development of a novel separation and preconcentration method based on dispersive micro solid phase extraction (D--SPE) technique for Se speciation is presented in this work. The nanosilica-IL hybrid material was obtained by direct contact of 1 mg of powdered nanosilica with 80 µL of a 5% (w/v) IL aqueous solution. The functionalization process was characterized by FT-IR and UV spectroscopies. The D--SPE method started with the selective formation of a complex between Se(IV) species and ammonium pyrrolidine dithiocarbamate (APDC)1 at pH 4, followed by the extraction from 5 ml of aqueous sample with the IL-functionalized nanosilica under vortex stirring. After a centrifugation step, the Se(IV)-APDC loaded nanosilica-IL hybrid was dried and eluted with 100 µL of a ethyl acetate-Triton X-114 solution prior to Se determination by ETAAS. An identical procedure was applied for total Se determination with a pre-reduction step and Se(VI) was calculated as the difference between total Se and Se(IV). Several factors affecting the functionalization, extraction and elution steps were evaluated. Thus, a retention efficiency of 100% and an enhancement factor of 45 were obtained, yielding LODs in the ppt range. The proposed method was successfully applied for the determination inorganic Se species in drinking and natural waters. Finally, considering the low mass of sorbent material and the negligible amount of organic solvent used, the proposed D--SPE method based on IL-functionalized nanosilica can be considered not only as an outstanding analytical tool, but also as a ?green?2 alternative to less environment-friendly methods.3,4 References:1 Martinis E.M., Escudero L.B., Berton P., Monasterio R.P., Filippini, M.F., Wuilloud, R.G., Talanta, 85(4), 2011, 2182.2 Sanderson, K., Nature, 469, 2011, 18.3 Wake, B.D., Bowie A.R., Butler E.C.V., Haddad, P.R., Trends in Analytical Chemistry, 23(7), 2014, 497.4 Pyrzyńska, K; Drzewicz, P; Trojanowicz, M., Analytica Chimica Acta, 363, 1998, 141.