Internal standardization combined with dilute-and-shoot preparation of distilled alcoholic beverages for Cu determination by high-resolution continuum source flame atomic absorption spectrometry

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Direct Determination of Phosphite in Fertilizers by Amperometric Titration

Amperometric titration using two Pt microelectrodes for the determination of phosphite in fertilizers based on the oxidation of analyte by iodine is proposed. The influence of pH, buffer composition, temperature, and foreign species on the end point and titration time was investigated. For titrations carried out at 70 degrees C using the pH 6.8 phosphate buffer, samples containing ca. 0.4% (m/v) P(2)O(5) could be titrated with 0.050 mol L(-1) iodine titrant, and the end point determined by extrapolating the linear portions of the plot to their intersection coincided with the end point identified by spectrophotometry. Accuracy was checked for phosphite determination in five fertilizer samples. Results were in agreement at the 95% confidence level (paired t test) with spectrophotometry. Recoveries of phosphite added to fertilizer samples ranged from 97% to 102% regardless of the amount of spiking in several determinations. The relative standard deviation (n = 10) was 1.0% for a diluted sample containing 0.050 mol L(-1) Na(2)HPO(3).

Evaluation and Application of TS-FF-AAS System Using Ceramic Tube as Atomization Cell for Tin Determination in Canned Foods

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development of a sensitive passive sampler using indigotrisulfonate for the determination of tropospheric ozone

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Evaluation of Ir and Pd(NO3)(2)/Mg(NO3)(2) as Modifiers for the Simultaneous Determination of Mn, Ni, Pb, and Sb in Fuel Ethanol by Graphite Furnace MS

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo voltamétrico de redissolução catódica de cefaloglicina em meio aquoso sobre eletrodo de mercúrio

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Determinação de biureto em uréia agroindustrial por espectrofotometria

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Direct determination of calcium in milk by atomic absorption spectrometry using flow-injection analysis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Determination of pesticides multiresidues in shallow groundwater in a cotton-growing region of Mato Grosso, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Optimization of photo-polymerized sol gel monolithic stationary phases prepared in polyacrylate-coated fused-silica capillaries for capillary electrochromatography

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Optical Fiber Relative Humidity Sensor Based on a FBG with a Di-Ureasil Coating

In this work we proposed a relative humidity (RH) sensor based on a Bragg grating written in an optical fiber, associated with a coating of organo-silica hybrid material prepared by the sol-gel method. The organo-silica-based coating has a strong adhesion to the optical fiber and its expansion is reversibly affected by the change in the RH values (15.0-95.0%) of the surrounding environment, allowing an increased sensitivity (22.2 pm/%RH) and durability due to the presence of a siliceous-based inorganic component. The developed sensor was tested in a real structure health monitoring essay, in which the RH inside two concrete blocks with different porosity values was measured over 1 year. The results demonstrated the potential of the proposed optical sensor in the monitoring of civil engineering structures.

Determination of herbicides residues in soil by small scale extraction

Herbicidas tais como trifluralina, simazina, atrazina, metribuzina e metolaclor são usados na agricultura brasileira. A eficiência de um método em pequena escala para a determinação destes herbicidas e dois produtos de degradação em amostras de solo foi avaliada. Os compostos foram extraídos das amostras de solo (5 g) com 20 ml de acetato de etila em agitador mecânico por 50 min. Após a extração, o sobrenadante foi filtrado em sulfato de sódio anidro, concentrado e analisado por cromatografia a gás de alta resolução com detector termiônico específico. Valores médios de recuperação obtidos de amostras de solo fortificadas em três níveis diferentes variaram de 81 a 115 % com valores de desvio padrão relativo entre 1,2 e 12,7 %. Os limites de detecção do método variaram de 0,01 a 0,06 mg kg-1. A metodologia foi aplicada a amostras de solo de fazendas localizadas próximas à cidade de Araraquara, estado de São Paulo, Brasil.

Relative antioxidant activity of Brazilian medicinal plants for gastrointestinal diseases

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Determinação turbidimétrica de dipirona em fluxo utilizando um reator contendo cloreto de prata imobilizado em resina poliéster

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação do emprego dos adsorventes: carvão ativo, chromosorb W e membrana C18 na preparação de amostras de ar para a determinação de d-aletrina em ambientes fechados

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)