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	Provedor de dados Scientia Agricola (3) Rev. Bras. Ciênc. Solo (2) Autor Bendassolli,José Albertino (5) Rossete,Alexssandra Luiza Rodrigues Molina (5) Carneiro,Josiane Meire Toloti (2) Sant Ana Filho,Carlos Roberto (2) Ignoto,Raquel de Fátima de (1) Máximo,Everaldo (1) Ribeiro,Daniela Neves (1) Sant'Ana Filho,Carlos Roberto (1) Tavares,Claudineia Raquel Oliveira (1) Tavares,Claudinéia Raquel de Oliveira (1) Trivelin,Paulo Cesar Ocheuze (1) Mais... Palavra-chave Stable isotope (3) Sample preparation (2) 34S (1) Isopropylamine salt (1) Isotopic determination (1) Isotopic determinations (1) Isotopic dilution (1) Labeled compounds (1) Labeled material (1) Lolium multiflorum (1) Mass spectrometry (1) Soil samples (1) Spectrophotometry (1) Stable isotopes (1) Sulfur 34 (1) Sulphur (1) Turbidimetric method (1) Mais... Tipo do documento Info:eu-repo/semantics/article (2) Info:eu-repo/semantics/report (2) Ano 2012 (1) 2010 (1) 2008 (2) 2006 (1) País Brazil (5) Idioma Inglês (5)		Ordenar por:  Relevância Autor Título Ano Registros recuperados: 5 Primeira ... 1 ... Última Organic sulfur oxidation to sulfate in soil samples for total sulfur determination by turbidimetry Rev. Bras. Ciênc. Solo Rossete,Alexssandra Luiza Rodrigues Molina; Bendassolli,José Albertino; Trivelin,Paulo Cesar Ocheuze. Sulfur in the soil occurs in two basic forms, organic and inorganic S. The organic form accounts for 95 % of S in most soils. The effectiveness of organic S to oxidate to sulfate was evaluated for total S determination in soil samples by wet (acid) and dry-ash (alkaline) oxidation methods. To evaluate the wet method and the possible use as a reference when evaluating the dry method proposed here, a reference standard from the US National Institute of Standards and Technology (NIST) was used (Montana Soil - NIST 2710). The dry-ash oxidation process with alkaline oxidizing agents is one of the simplest oxidation methods of organic S to the sulfate form and was compared with the wet process. The objective of the study was to develop a dry method that would be... Tipo: Info:eu-repo/semantics/report Palavras-chave: Sample preparation; Turbidimetric method; Spectrophotometry. Ano: 2008 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832008000600031 Isotope determination of sulfur by mass spectrometry in soil samples Rev. Bras. Ciênc. Solo Rossete,Alexssandra Luiza Rodrigues Molina; Carneiro,Josiane Meire Toloti; Sant Ana Filho,Carlos Roberto; Bendassolli,José Albertino. Sulphur plays an essential role in plants and is one of the main nutrients in several metabolic processes. It has four stable isotopes (32S, 33S, 34S, and 36S) with a natural abundance of 95.00, 0.76, 4.22, and 0.014 in atom %, respectively. A method for isotopic determination of S by isotope-ratio mass spectrometry (IRMS) in soil samples is proposed. The procedure involves the oxidation of organic S to sulphate (S-SO4(2-)), which was determined by dry combustion with alkaline oxidizing agents. The total S-SO4(2-) concentration was determined by turbidimetry and the results showed that the conversion process was adequate. To produce gaseous SO2 gas, BaSO4 was thermally decomposed in a vacuum system at 900 ºC in the presence of NaPO3. The isotope... Tipo: Info:eu-repo/semantics/article Palavras-chave: Sample preparation; Soil samples; Isotopic dilution; Labeled material; Stable isotope; 34S. Ano: 2012 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832012000600012 Production of 34S-labeled gypsum (Ca34SO4.2H2O) Scientia Agricola Rossete,Alexssandra Luiza Rodrigues Molina; Bendassolli,José Albertino; Máximo,Everaldo; Sant Ana Filho,Carlos Roberto; Ignoto,Raquel de Fátima de. Agricultural gypsum (CaSO4.2H2O) stands out as an effective source of calcium and sulfur, and to control aluminum saturation in the soil. Labeled as 34S it can elucidate important aspects of the sulfur cycle. Ca34SO4.2H2O was obtained by chemical reaction between Ca(OH)2 and H2(34)SO4, performed under slow agitation. The acid was produced by ion exchange chromatography using the Dowex 50WX8 cation exchange resin and a Na2(34)SO4 eluting solution. After precipitation, the precipitate was separated and dried in a ventilated oven at 60ºC. From 2.2 L H2SO4 0.2 mol L-1 and 33.6 g Ca(OH)2, 73.7 ± 0.6 g Ca34SO4.2H2O were produced on average in the tests, representing a mean yield of 94.6 ± 0.8%, with 98% purity. The 34SO2 gas was obtained from Ca34SO4.2H2O in the... Tipo: Info:eu-repo/semantics/article Palavras-chave: Sulfur 34; Stable isotope; Isotopic determination. Ano: 2006 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162006000400012 Production of single superphosphate labeled with 34S Scientia Agricola Rossete,Alexssandra Luiza Rodrigues Molina; Carneiro,Josiane Meire Toloti; Bendassolli,José Albertino; Tavares,Claudineia Raquel Oliveira; Sant'Ana Filho,Carlos Roberto. Single superphosphate is currently one of the mostly used fertilizers as an alternative source for phosphorus and sulphur. Sulphur presents four stable isotopes (32S, 33S, 34S, and 36S) with natural abundances of 95.00; 0.76; 4.22; and 0.014% in atoms, respectively. Single superphosphate labeled with the 34S isotope was obtained from a chemical reaction in stoichiometric amounts between Ca(H2PO4)2 and Ca34SO4.2H2O. Calcium sulphate (Ca34SO4.2H2O) was enriched with 5.85 ± 0.01 atoms % of 34S. The Ca(H2PO4)2 reagent was obtained from a reaction between CaCl2.2H2O and H3PO4. The reaction between the Ca(H2PO4)2 thus produced and the labeled Ca34SO4.2H2O compound was then performed to obtain the 34S-labeled single surperphosphate. The thermal decomposition of... Palavras-chave: Isotopic determinations; Sulphur; Stable isotopes; Mass spectrometry; Labeled compounds. Ano: 2008 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162008000100013 15N-labeled glyphosate synthesis and its practical effectiveness Scientia Agricola Tavares,Claudinéia Raquel de Oliveira; Bendassolli,José Albertino; Ribeiro,Daniela Neves; Rossete,Alexssandra Luiza Rodrigues Molina. Glyphosate is the herbicide with the greatest participation in the world market, and it has been used intensively in agriculture for over 30 years, especially because of its relatively low cost and high effectiveness on different species. This study describes a synthesis method of glyphosate in the form of the isopropylamine salt enriched in the stable nitrogen isotope (15N). The 15N-herbicide synthesis was performed using a phosphomethylation reaction with dialkyl phosphite and 15N-glycine. The tests were conducted at a microscale and equimolar quantities. A 20% yield was obtained at the established conditions. To test the effectiveness of the synthesized glyphosate, an experiment was performed in a growth chamber with the weed Lolium multiflorum... Tipo: Info:eu-repo/semantics/report Palavras-chave: Lolium multiflorum; Isopropylamine salt; Stable isotope. Ano: 2010 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162010000100014 Registros recuperados: 5 Primeira ... 1 ... Última

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