https://repositorio.ufba.br/handle/ri/1995 Sun, 03 May 2026 06:35:33 GMT 2026-05-03T06:35:33Z https://repositorio.ufba.br/handle/ri/17274 Título: Strontium mono-chloride — A new molecule for the determination of chlorine using high-resolution graphite furnace molecular absorption spectrometry and direct solid sample analysis Autor(es): Pereira, Éderson R.; Welz, Bernhard; Lopez, Alfredo H. D.; Gois, Jefferson S. de; Caramori, Giovanni Finoto; Borges, Daniel L. G.; Carasek, Eduardo; Andrade, Jailson Bittencourt de Abstract: A new method has been developed for the determination of chlorine in biological reference materials using high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) of the strontium mono-chloride (SrCl) molecule and direct solid sample analysis. The use of the SrCl molecule for high-temperature MAS was not described up to now in the literature. Preliminary time-dependent density functional theory calculations of the SrCl structure were carried out in order to obtain reasonable estimates of the absorption spectrum of the target molecule. The calculations, which were carried out at BHandHLyp/def2-QZVP level of theory, proved a very accurate and inexpensive way to get information about the spectrum of the SrCl molecule, which enabled us to perform the Cl determination with good sensitivity and specificity. The molecular absorption of the SrCl molecule has been measured using the wavelength at 635.862 nm, and zirconium and palladium have been evaluated as the chemical modifiers in order to increase the sensitivity of the gaseous SrCl molecule generated in the graphite furnace. The pyrolysis and vaporization temperatures were 600 °C and 2300 °C, respectively. Accuracy and precision of the method have been evaluated using biological certified reference materials of both animal and plant origins, showing good agreement with the informed and certified values. Limit of detection and characteristic mass were 1.0 and 2.2 ng, respectively. The results found using HR-CS GF MAS were in agreement (95% confidence level) compared to those obtained by electrothermal vaporization-inductively coupled plasma mass spectrometry. Tipo: Artigo de Periódico Wed, 01 Jan 2014 00:00:00 GMT https://repositorio.ufba.br/handle/ri/17274 2014-01-01T00:00:00Z https://repositorio.ufba.br/handle/ri/17272 Título: Influence of Temperature and Time of Seed Aging on the Properties of Beta Zeolite/MCM-41 Materials Autor(es): T. F, Grecco Saulo; Ernesto, Urquieta González A.; Patrício, Reyes; Marcelo, Oportus; Carmo, Rangel Maria do Abstract: The diffusion restrictions of the reactants caused by the micropores limit the use of zeolites for processing heavy molecules. This demands the development of materials that combine the properties of zeolites and mesoporous materials. With this goal in mind, the influence of temperature and time of seed aging on the properties of beta zeolite/MCM-41 materials obtained by mesostructuration/ crystallization was studied in this work. It was noted that the most suitable conditions to obtain the crystalline microporous phase of beta zeolite and the MCM-41 mesoporous phase was 140 °C, during 24 h of seed aging. At the other temperatures (60 and 90 °C) poor crystallized solids and a lamellar phase of MCM-50 were produced. On the other hand, increasing time of aging seeds bigger crystals of crystalline beta zeolite and less organized mesoporous phases were obtained at 140 °C. Tipo: Artigo de Periódico Wed, 01 Jan 2014 00:00:00 GMT https://repositorio.ufba.br/handle/ri/17272 2014-01-01T00:00:00Z https://repositorio.ufba.br/handle/ri/17234 Título: Slurry Sampling and HG AFS for the Determination of Total Arsenic in Rice Samples Autor(es): Santos, Walter Nei Lopes dos; Cavalcante, Dannuza D.; Macedo, Samuel Marques; Nogueira, Jéssica S.; Silva, Erik Galvão Paranhos da Abstract: This paper proposes a procedure for the determination of total arsenic in rice using slurry sampling and hydride generation atomic fluorescence spectrometry (HG AFS). During optimization, water, hydrochloric acid, and nitric acid solutions were tested as extractor. Best results were found using 2.0 mol L−1 nitric acid solutions. The slurries are prepared using 200 mg of rice sample, 5.0 mL of nitric acid solution, and sonication for 30 min. Then, an aliquot of 5.0 mL of the slurry was taken and 3.0 mL of 1.5 mol L−1 hydrochloric acid solution and 1.5 mL of 10 % potassium iodide in 2 % ascorbic acid solution were added. After 30 min, the volume was completed up to 10 mL with ultra-pure water and arsenic quantified by HG AFS. In these experimental conditions, the method allows the determination of arsenic employing external calibration, with limits of detection and quantification of 1.1 and 3.3 ng g−1 and precision expressed as relative standard deviation (%RSD) varying between 5.9 and 1.3 % for arsenic concentration of 0.12 and 0.47 μg g−1. Accuracy was confirmed by analysis of the NIES standard reference material for rice flour, SRM 10b. This method was used to determine the arsenic content in 20 rice samples that were purchased at supermarkets in Salvador, Bahia, Brazil. The arsenic content for the three types of rice (white, parboiled, and brown) varied from 0.12 and 0.47 μg g−1. Some of the samples were also analyzed by HG AFS after complete mineralization in block digester employing a reflux system (cold finger). A statistical test showed that there was no significant difference between the results obtained using slurry sampling and those obtained after complete digestion of the sample. Tipo: Artigo de Periódico Tue, 01 Jan 2013 00:00:00 GMT https://repositorio.ufba.br/handle/ri/17234 2013-01-01T00:00:00Z https://repositorio.ufba.br/handle/ri/17120 Título: Exposure to carbonyl compounds in charcoal production plants in Bahia, Brazil Autor(es): Carvalho, Albertinho Barreto de; Kato, Mina; Rezende, Mariângela M.; Pereira, Pedro Afonso de Paula; Andrade, Jailson Bittencourt de Abstract: Studies have investigated the exposure levels of carbonyl compounds (CC) in the indoor and outdoor air of homes, vehicles, workplaces, urban and industrial areas, and rural sites. However, an investigation of these emissions and occupational exposure to CC in charcoal production facilities has not been previously conducted. The objective of this study was to measure the atmospheric concentrations of several CC to assess the exposure of workers of two charcoal plants located north of Salvador, Bahia, Brazil. Stationary and personal samples were collected using Sep-Pak® C18 cartridges that were coated with a 0.2 % acidic solution of 2,4-dinitrophenylhydrazine. The quantification of the resulting 2,4-dinitrophenylhydrazone derivatives was conducted using a high-performance liquid chromatography system with UV detection. In the personal samples, the concentrations of formaldehyde, acetaldehyde, propanone, furfural, and C4 isomers (n-butanal-isobutanal-butanone) ranged from 12 to 139, 38 to 165, 136 to 483, 39 to 114, and 63 to 132 μg m−3, respectively. In the stationary samples, the concentrations of these CC ranged from 20 to 160, 111 to 284, 328 to 644, 70 to 163, and 100 to 176 μg m−3, respectively. When compared to the occupational exposure limits for 8 h, the concentrations of formaldehyde were often greater than the levels recommended by the American National Institute for Occupational Safety and Health, which indicates a health risk for charcoal workers. These results are the first reported concerning the occupational exposure to CC in charcoal plants. Tipo: Artigo de Periódico Tue, 01 Jan 2013 00:00:00 GMT https://repositorio.ufba.br/handle/ri/17120 2013-01-01T00:00:00Z