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Your search keyword '"Cassella, Ricardo J."' showing total 373 results
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373 results on '"Cassella, Ricardo J."'

2. Metal-contaminated biochars as cheap and more sustainable catalysts for furfural conversion to value-added compounds

Author

Madriaga, Vinicius G.C., Mattos, João Pedro R., Rossa, Vinicius, Ferreira, Luanne E.M., Vasconcelos, Sancler C., Silva, Domingos S.A., Rocha, Pamela S.M., dos Santos, Rodrigo D., Silva, Ludmila P.C., Araujo, Joyce R., Urquieta-González, Ernesto A., Romeiro, Gilberto A., Cassella, Ricardo J., Lima, Thiago M., and Passos, Fabio B.

Published
2022
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4. Elemental Analysis of Dietary Supplements by Microwave-Induced Plasma–Optical Emission Spectrometry (MIP-OES) With Ultrasound-Assisted Extraction (UAE).

Author

da Silva, Andressa Barcelos P., Barreto, Larissa M. L., Araújo, André S., and Cassella, Ricardo J.

Subjects
INDUCTIVELY coupled plasma atomic emission spectrometry, DIETARY supplements, COPPER, MICROWAVE ovens, ELEMENTAL analysis
Abstract

The purpose of this study was to demonstrate the feasibility of determining metals (Cr, Mn, Zn, Fe, and Cu) in commercial dietary supplements using microwave-induced plasma optical emission spectrometry (MIP OES) after fast ultrasound-assisted extraction. Various parameters affecting the extraction process, such as the nature and concentration of the extractant solution, sonication time, and sample mass, were evaluated. Under the optimal conditions, it was possible to quantitatively extract metals from the samples by sonicating 1.0 g of the supplement dispersed throughout 25 mL of a 1.0 mol L−1 HNO3 for only 5 min. The developed method was applied to determine the analytes in four dietary supplements available in the Brazilian market. The results obtained with the extraction method were compared with the values obtained when the samples were completely mineralized with concentrated HNO3 in a microwave oven. There were no statistical differences between the developed and reference methods when the paired Student's t-test was applied with a 95% confidence level. The application of ultrasound-assisted extraction was demonstrated to be advantageous compared to total sample digestion. This approach allowed the use of a higher mass of the sample, thereby enhancing the analytical capability of the method. Furthermore, employing less severe conditions, such as lower energy and a diluted acid solution, simplified and reduced the cost of the procedure compared to mineralization. [ABSTRACT FROM AUTHOR]

Published
2025
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31. Dispersive Liquid Phase Microextraction (DLPME) as a Strategy for CdII Separation and Determination in High-Salinity Produced Waters by Graphite Furnace Atomic Absorption Spectrometry

Author

Robaina, Nicolle F., Cruz, Graziela F. B., and Cassella, Ricardo J.

Subjects
produced waters, dispersive liquid phase microextraction, cadmium, saline waters
Abstract

In this study, we propose a microextraction method for the determination of CdII in produced waters. The process is based on the conversion of CdII ions into a hydrophobic diethyldithiocarbamate (DDTC) complex with its subsequent dispersive liquid phase microextraction (DLPME) from the aqueous medium with chloroform. The organic phase was then diluted with ethanol and Cd absorbance was measured by graphite furnace atomic absorption spectrometry (GF AAS). The experimental conditions related to the DLPME process were investigated, and the best microextraction conditions were achieved at pH = 6.0 (acetate buffer), 7.5 × 10-6 mol L-1 of DDTC, and when using 200 µL of chloroform as the extracting solvent. No dispersing solvent was needed, which allowed the recovery of approximately 140 µL of chloroform extract. Pyrolysis and atomization temperatures of the GF AAS program were determined through the construction of the respective curves. The estimated limits of detection (LOD) and quantification (LOQ) were 5 and 17 ng L-1, respectively, whereas the enrichment factor for the method was 17. Six samples of seawater and five samples of produced waters with salinities between 30 and 270‰ were analyzed as well as two certified reference materials of saline waters.

Published
2023

39. Simple Spectrophotometric Determination of Iron in Diesel Oil after Sample Preparation Employing Extraction Induced by Emulsion Breaking

Author

Pereira, Thamiris V. and Cassella, Ricardo J.

Subjects
iron, spectrophotometry, diesel oil, extraction induced by emulsion breaking
Abstract

This work reports the development of a simple and fast method for the spectrophotometric determination of Fe in diesel oil using the classic reaction with 1,10-phenanthroline after its extraction induced by emulsion breaking (EIEB). The extraction parameters of EIEB were optimized (concentration of HNO3 and Triton X-100® in the emulsifying solution) as well as the adjustment of the pH of the final solution, a necessary step to complete the colorimetric reaction. The developed method presented a limit of detection of 0.004 mg L-1 and a limit of quantification of 0.013 mg L-1 and was applied in the analysis of six samples of diesel oil with different specifications. The results were statistically similar to those obtained by graphite furnace atomic absorption spectrometry (GF AAS). A recovery test was also performed by spiking the samples with 1.0 mg L-1 of Fe in the form of an organometallic compound, yielding recovery percentages between 83 and 108%.

Published
2022

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