Amostragem direta de sorvente sólido magnético em espectrometria de absorção atômica com chama para a determinação de chumbo em água.

Abstract

This work describes, for the first time, the direct magnetic sorbent sampling for flame

atomic absorption spectrometry (DMSS-FAAS). A magnetic graphene oxide aerogel (M- GOA) was synthesized and characterized by transmission electron microscopy, gas

sorption porosimetry, infrared spectroscopy, Raman, thermogravimetric analysis, X-ray and vibrating sample magnetometry. The material was then used in the magnetic dispersive solid phase extraction (d-MSPE) of lead from water sample. Then, an magnetized probe was inserted into the sample vial, and M-GOA particles were captured in the conic tip. The probe was then inserted in the base flame, the M-GOA particles were heated (losing their magnetic susceptibility), being transported by the flame, and atomized in front of the otical path. Sample volume and pH, mass of particles and agitation time were optimized for factorial design and Dohlert matrix. The study of interferent ions was carried out by design to evaluate the influence of Al3+ Cr3+, Co2+ Cu2+, Fe3+, Mn2+

, Ba2+, Mg2+, Li+ , Na+ , K+ , Ca2+, F- , NO3 - , SO4 2- , NO2 - , CN- and Clin the lead determination. No significant inferences wer observed. The analytical parameters were: linear range from 5 to 180 μg L-1

; LD of 1.30 μg L-1 and LQ of 4.34 μg L-1 . The sensitivity of the DMSS-FAAS method was 41 times higher than the conventional FAAS analyses (via nebulization system without preconcentration step). The detection of the proposed method was sufficient for the determination of lead in water, with the limits established by Ministry of Healthy (10 μg L-1

for drinking water), and can be compared to other analytical techniques with higher sensitivities such as GFAAS and TS-FF-AAS conventional. The performance of the method was also evaluated for cadmium, copper and lead ions using magnetic materials nanotubes (M-CNTs), restricted access magnetic carbon nanotubes (M-RACNTs), methacrylic acid-co-ethylene glycol

dimethacryt) (M - PMA), magnetic nanoparticles coated with orange peel powder (M- OPP) and nanoparticles coated with SiO2 (M-TEOS). The analytical signals obtained

increased significantly when compared to the traditional detection method by FAAS, evidencing high applicability of the proposed method. The main advantages presented by this method were simplicity, low cost, high analytical frequency, high detectability and reproducibility and high potential for the determination of metals in water samples. Key words: lead. dispersive solid-phase extraction. magnetic aerogel graphene oxide. direct atomization. flame atomic absorption spectrometry. direct magnetic solid sampling flame atomic absorption spectrometry.