Determination of Cu, Ni, Mn, and Pb in diesel oil samples using reversed-phase vortex-assisted liquid-liquid microextraction associated with energy dispersive X-ray fluorescence spectrometry

Vanessa de Jesus Ferreira; Jorge S Almeida; Valfredo A Lemos; Olívia M C de Oliveira; Karina S Garcia; Leonardo S G Teixeira

doi:10.1016/j.talanta.2020.121514

Determination of Cu, Ni, Mn, and Pb in diesel oil samples using reversed-phase vortex-assisted liquid-liquid microextraction associated with energy dispersive X-ray fluorescence spectrometry

Talanta. 2021 Jan 15:222:121514. doi: 10.1016/j.talanta.2020.121514. Epub 2020 Aug 7.

Authors

Vanessa de Jesus Ferreira¹, Jorge S Almeida¹, Valfredo A Lemos², Olívia M C de Oliveira³, Karina S Garcia³, Leonardo S G Teixeira⁴

Affiliations

¹ Universidade Federal da Bahia, Instituto de Química, Departamento de Química Analítica, Campus Universitário de Ondina, 40170-115, Salvador, Bahia, Brazil.
² Universidade Estadual do Sudoeste da Bahia, Laboratório de Química Analítica, Rua José Moreira Sobrinho S/n, Jequiezinho, 45206-190, Jequié, Bahia, Brazil.
³ Universidade Federal da Bahia, Instituto de Geociências, Campus Universitário de Ondina, 40170-280, Salvador, Bahia, Brazil.
⁴ Universidade Federal da Bahia, Instituto de Química, Departamento de Química Analítica, Campus Universitário de Ondina, 40170-115, Salvador, Bahia, Brazil; Instituto Nacional de Ciência e Tecnologia, INCT, de Energia e Ambiente, Universidade Federal da Bahia, 40170-115, Salvador, Bahia, Brazil. Electronic address: lsgt@ufba.br.

PMID: 33167225
DOI: 10.1016/j.talanta.2020.121514

Abstract

A method was developed based on reversed-phase vortex-assisted liquid-liquid microextraction (RP-VALLME) combined with energy dispersive X-ray fluorescence (EDXRF) spectrometry for the determination of Cu, Mn, Ni, and Pb in diesel oil samples. In this procedure, a nitric acid solution was used as the extraction phase to isolate analytes from organic samples. After a centrifugation step, the aqueous phase was added dropwise to a filter paper disc for EDXRF determinations. The following variables were optimized: type of extraction phase solution, concentration of the extraction phase, stirring time, and sample volume. Some instrumental parameters were also evaluated: atmospheric condition, irradiation energy, and irradiation time. Using 100 μL of a 0.075 mol L^-1 nitric acid solution as the extraction phase for a sample volume of 5.0 mL and a stirring time of 45 s, the limits of detection were 14, 8, 10, and 7 μg L^-1 for Cu, Mn, Ni, and Pb, respectively. The enrichment factors obtained were 34 (Cu), 62 (Mn), 59 (Ni), and 64 (Pb). The precisions, expressed as relative standard deviations (RSDs, %), were calculated from ten replications of the experiment under optimized conditions using standard solutions containing 200 μg L^-1 and 400 μg L^-1 of all four analytes and ranged between 2.1 and 6.4%. The results of recovery tests ranged from 87 to 112%. The proposed procedure was efficiently applied to the determination of the four analytes in diesel oil samples. The results were compared with those obtained by inductively coupled plasma optical emission spectrometry (ICP-OES) after sample digestion, and no significant differences were found.

Keywords: Diesel oil; Energy dispersive X-ray fluorescence spectrometry; Multielement determination; Reversed-phase vortex-assisted liquid-liquid microextraction.