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Your search keyword '"Dias, Fabio de S."' showing total 27 results
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27 results on '"Dias, Fabio de S."'

13. Liquid-phase extraction combined with X-ray fluorescence spectrometry for the elemental determination.

Author

Ferreira, Vanessa J., Virgens, Fernanda B. S., Pires, Laís N., Dias, Fabio de S., Lemos, Valfredo A., and Teixeira, Leonardo S. G.

Subjects
FLUORESCENCE spectroscopy, X-ray fluorescence, HOLLOW fibers, SPECTROMETRY
Abstract

X-ray fluorescence spectrometry (XRF) has been widely used for multi-element determination in various samples. However, when trace level determination is required, separation and preconcentration procedures are often used as a step before detection to avoid or reduce interferences and to increase sensitivity. Liquid-phase extraction (LPE) is one of the most well-known and applied pretreatment techniques associated with atomic spectrometry due to its simplicity, speed, and ease of automation. A review of methods involving LPE combined with XRF is presented. Methods described in the literature are discussed, involving conventional LPE and the three main categories of liquid-phase microextraction (LPME): single-drop microextraction (SDME), dispersive liquid–liquid microextraction (DLLME), and hollow fiber liquid-phase microextraction (HF-LPME). Characteristics of the methods are presented, considering experimental aspects, analytical features, advantages, and disadvantages. In addition, trends in the association between LPME techniques and XRF are presented. [ABSTRACT FROM AUTHOR]

Published
2023
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14. Solid phase extraction combined with energy dispersive X-ray fluorescence spectrometry for multielement determination.

Author

Guimarães, Leonardo B., Teixeira, Leonardo S. G., Amorim, Fabio A. C., and Dias, Fabio de S.

Subjects
FLUORESCENCE spectroscopy, X-ray fluorescence, SOLID phase extraction
Abstract

In this review, general aspects of the combination of the solid phase extraction (SPE) with energy dispersive X-ray fluorescence spectrometry (EDXRF) for multielement determination are presented. Derivations of SPE, such as dispersive solid phase extraction (DSPE), dispersive micro-solid phase extraction (DµSPE), and dispersive magnetic micro-solid phase extraction DM-µSPE are also presented, showing the possibility of direct analysis of the solid phase. The sorbents, advantages, disadvantages, and the analytical characteristics of the combination followed by direct determination of analytes retained on the solid phase are discussed. Furthermore, the perspectives of this analytical arrangement are presented. [ABSTRACT FROM AUTHOR]

Published
2023
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25. Biodiesel Trace Element Analysis by Energy Dispersive X-ray Fluorescence Spectrometry Using Magnetic Solid-Phase Microextraction

Author

Meira, Lucilia A., Almeida, Jorge S., Oliveira, Maiara S., Dias, Fabio de S., Queiroz, Antonio F. S., Soares, Sarah A. R., and Teixeira, Leonardo S. G.

Abstract

One parameter to examine biodiesel quality has to do with the existence of metals, given that their presence can negatively affect fuel stability, by virtue of the alteration to their physicochemical properties. Given the significance of monitoring the concentration of metals in biodiesel, this work is aimed at developing a different mode for multielement determination through the use of energy dispersive X-ray fluorescence (EDXRF) spectrometry. For this purpose, an extraction procedure using sample preparation by emulsification associated with magnetic solid-phase microextraction was proposed for separation of Cd, Pb, Cr, V, and Mo from biodiesel samples for posterior analysis using EDXRF spectrometry. The emulsion was prepared by mixing the sample with n-propyl alcohol and 0.01 mol L–1nitric acid alongside subsequent contact with the solid phase (CoFe2O4nanoparticles impregnated with alizarin fluorine blue). Constrained mixing design was used to optimize the emulsion composition, and the recommended conditions were 36% (v v–1) n-propyl alcohol, 42% (v v–1) biodiesel, and 22% (v v–1) nitric acid solution for a total volume of 10 mL, using 100 mg of nanoparticles. The proposed extraction allowed enrichment factors of 9.3, 23, 27, 9.7, and 10 for Cd, Cr, V, Pb, and Mo, respectively. The limits of detection were found to be 13, 32, 17, 14, and 25 μg kg–1for Cd, Pb, Cr, V, and Mo, respectively. Recovery tests were performed by adding 200 μg kg–1of all analytes in question to six varying biodiesel samples with outcomes that registered between 85 and 114%. The recommended procedure was applied in the analysis of biodiesel, and the highest concentrations observed were 166 μg kg–1for Cd, 106 μg kg–1for Cr, 137 μg kg–1for Pb, 82 μg kg–1for V, and 92 μg kg–1for Mo.

Published
2021
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