Direct magnetic sorbent sampling flame atomic absorption spectrometry (DMSS-FAAS) for highly sensitive determination of trace metals

Lucimara Mendonça Costa; Fabrício Alves Borges; Marcello Henrique da Silva Cavalcanti; Ayla Campos do Lago; César Ricardo Teixeira Tarley; Giovana de Fátima Lima Martins; Eduardo Costa Figueiredo

doi:10.1016/j.aca.2022.340709

Direct magnetic sorbent sampling flame atomic absorption spectrometry (DMSS-FAAS) for highly sensitive determination of trace metals

Anal Chim Acta. 2023 Apr 22:1251:340709. doi: 10.1016/j.aca.2022.340709. Epub 2022 Dec 10.

Authors

Lucimara Mendonça Costa¹, Fabrício Alves Borges¹, Marcello Henrique da Silva Cavalcanti², Ayla Campos do Lago¹, César Ricardo Teixeira Tarley³, Giovana de Fátima Lima Martins², Eduardo Costa Figueiredo⁴

Affiliations

¹ Laboratory of Toxicant and Drug Analyses, Faculty of Pharmaceutical Sciences, Federal University of Alfenas, 37130-001, Alfenas, MG, Brazil; Institute of Chemistry, Federal University of Alfenas, 37130-001, Alfenas, MG, Brazil.
² Institute of Chemistry, Federal University of Alfenas, 37130-001, Alfenas, MG, Brazil.
³ Department of Chemistry, State University of Londrina, Rodovia Celso Garcia Cid. 445, Km 380, Londrina, 86057-970, PR, Brazil.
⁴ Laboratory of Toxicant and Drug Analyses, Faculty of Pharmaceutical Sciences, Federal University of Alfenas, 37130-001, Alfenas, MG, Brazil. Electronic address: eduardo.figueiredo@unifal-mg.edu.br.

PMID: 36925273
DOI: 10.1016/j.aca.2022.340709

Abstract

A procedure of direct magnetic sorbent sampling in flame atomic absorption spectrometry (DMSS-FAAS) was developed in this work. Metal-loaded magnetic sorbents were directly inserted in the flame of the FAAS for direct metal desorption/atomization. Magnetic graphene oxide aerogel (M-GOA) particles were synthesized, characterized, and used as a proof-of-concept in the magnetic dispersive solid phase extraction of Pb²⁺ ions from water samples. M-GOA was selected because is a light and porous sorbent, with high adsorption capacity, that is quickly burned by the flame. Magnetic particles were directly inserted in the flame by using a metallic magnetic probe, thereby avoiding the need for a chemical elution step. As all the extracted Pb²⁺ ions arrive to the flame without passing through the nebulization system, a drastic increase in the analytical signal was achieved. The improvement in the sensitivity of the proposed method (DMSS-FAAS) for Pb²⁺ determination was at least 40 times higher than the conventional procedure in which the Pb²⁺ is extracted, eluted, and analyzed by conventional flame atomic absorption spectrometry (FAAS) via the nebulization system. The analytical curve was linear from 5.0 to 180.0 μg L^-1 and the limit of detection was found to be 1.30 μg L^-1. Background measurements were insignificant, and the atomic absorption peaks were narrow and reproducible. Precision assessed as a percentage of the relative standard deviation %RSD was found to be 17.4, 7.1, and 7.8% for 10, 70, and 180 μg L^-1 levels, respectively. The method showed satisfactory results even in the presence of other ions (Al³⁺, Cr³⁺, Co²⁺, Cu²⁺, Fe³⁺, Mn²⁺, Ba²⁺, Mg²⁺, and Li⁺). The performance of the new system was also evaluated for Cd²⁺ ions, as well as by using other magnetic particles available in our lab: magnetic carbon nanotubes (M-CNTs), magnetic restricted access carbon nanotubes (M-RACNT), magnetic poly (methacrylic acid-co-ethylene glycol dimethacrylate) (M-PMA), magnetic nanoparticles coated with orange powder peel (M-OPP), and magnetic nanoparticles covered with SiO₂ (M - SiO₂). Analytical signals increased for both analytes in all sorbents (increases of about 4-37 times), attesting the high potential and applicability of the proposed method. Simplicity, high analytical frequency, high detectability and reproducibility, low cost, and possibility of being totally mechanized are the most relevant advantages.

Keywords: DMSS; Direct magnetic sorbent sampling; Dispersive solid-phase extraction; Flame atomic absorption spectrometry; Magnetic aerogel graphene oxide; Magnetic particles; Metal.