Publications by authors named "Geovani C Brandao"

Silver nanoparticles (AgNPs) synthesized from green synthesis using medicinal plants are presented as an option for the development of new antimicrobial agents. In this context, this study aims to evaluate the antimicrobial activity of silver nanoparticles synthesized from the aqueous extract of Schinus terebinthifolius Raddi leaves, popularly known as "aroeira." A 2 factorial design was used to assess the statistical significance of the studied factors, and Box-Behnken design was used to define the optimal conditions for the green synthesis of AgNPs.

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In this study, mineral composition, centesimal composition and lead were evaluated in pine nut seeds (raw and cooked) from five Brazilian states. Mineral composition was determined by ICP OES and lead by GF AAS. The results for minerals were evaluated by Boxplot, PCA and HCA, using the R software.

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Honey is a food of nutritional, medicinal and commercial importance. The physicochemical characteristics, pollen spectrum and mineral composition of eighteen honey samples obtained from regions (Cachoeira, Coqueiros, Maragojipe and Santiago do Iguape) near the Paraguaçu River, Bahia, Brazil were evaluated. Botanical families Asteraceae, Leguminosae, Malvaceae, Myrtaceae and Palmae were most frequently found.

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In this work, an analytical method for the determination of Cd and Pb in natural coconut water samples, industrialized coconut water samples and coconut milk using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS), after minimum treatment of the sample was developed. The analytical method was applied to 46 samples collected in Salvador, Bahia (Brazil). The ranges of concentrations obtained were: 0.

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A method for simultaneous determination of Fe (232.036 nm) and Ni (232.195 nm) in vegetable oil samples by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) after an acid extraction of the analytes is proposed.

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This work proposes a method for the determination of free and total sulfur(IV) compounds in coconut water samples, using the high-resolution continuum source molecular absorption spectrometry. It is based on the measurement of the absorbance signal of the SO gas generate, which is resultant of the addition of hydrochloric acid solution on the sample containing the sulfating agent. The sulfite bound to the organic compounds is released by the addition of sodium hydroxide solution, before the generation of the SO gas.

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This paper presents a method for determining phospholipids in soybean lecithin samples by phosphorus determination using high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) via molecular absorption of phosphorus monoxide. Samples were diluted in methyl isobutyl ketone. The best conditions were found to be 213.

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A method was established to simultaneously determine cadmium, iron and tin in canned-food samples using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS). The quantification step has been performed using the primary line (228.802nm) for cadmium and the adjacent secondary lines (228.

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The present work proposed an analytical method for the direct determination of chromium in infant formulas employing the high-resolution continuum source electrothermal atomic absorption spectrometry combined with the solid sample analysis (SS-HR-CS ET AAS). Sample masses up to 2.0mg were directly weighted on a solid sampling platform and introduced into the graphite tube.

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In this work, a homogeneity study of a corn flour reference material candidate for inorganic analysis is presented. Seven kilograms of corn flour were used to prepare the material, which was distributed among 100 bottles. The elements Ca, K, Mg, P, Zn, Cu, Fe, Mn and Mo were quantified by inductively coupled plasma optical emission spectrometry (ICP OES) after acid digestion procedure.

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In this work, it was developed a method for the determination of nitrite and nitrate in groundwater by high-resolution continuum source electrothermal molecular absorption spectrometry of NO produced by thermal decomposition of nitrate in a graphite furnace. The NO line at 215.360 nm was used for all analytical measurements and the signal obtained by integrated absorbance of three pixels.

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A simple method has been developed to determine antimony and lead in pewter alloy cups produced in Brazil, using fast sequential determination by high-resolution continuum source flame atomic absorption spectrometry. The samples were dissolved in HCl and H(2)O(2), employing a cold finger system in order to avoid analyte losses. The main resonance line of lead at 217.

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In the present work, we propose a method for the determination of nitrite based on the chemical generation of nitric oxide (NO) and its detection by high-resolution continuum source molecular absorption spectrometry. NO is generated by the reduction of nitrite in acidic media with ascorbic acid as the reducing agent and then transferred into a quartz cell by a stream of argon carrier gas. The conditions under which the NO is generated are as follows: 0.

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This paper presents an analytical procedure for the direct determination of zinc in yogurt employing sampling slurry and high resolution-continuum source flame atomic absorption spectrometry (HR-CS FAAS). The step optimization established the experimental conditions of: 2.0molL(-1) hydrochloric acid, a sonication time of 20min and a sample mass of 1.

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A procedure is proposed for the direct determination of manganese and iron in wine employing fast sequential flame atomic absorption spectrometry and the reference element technique to correct for matrix effects. Cobalt, silver, nickel and indium have been tested as reference elements. The results demonstrated that cobalt and indium at a concentration of 2 and 10mgL(-1) were efficient for quantification of manganese and iron, respectively.

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In this paper, we proposed a procedure for the determination of iron(II) and total iron in wine samples employing molecular absorption spectrophotometry. The ligand used is 2-(5-bromo-2-pyridylazo)-5-(diethylamino)-phenol (Br-PADAP) and the chromogenic reaction in absence or presence of ascorbic acid (reducing agent) allows the determination of iron(II) or total iron, respectively. The optimization step was performed using a multivariate technique (Box Behnken design) involving the factors pH, acid ascorbic concentration and reaction time.

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An automatic on-line pre-concentration system is proposed for lead determination in drinking water using flame atomic absorption spectrometry (FAAS). Lead(II) ions are retained as the 1-(2-pyridylazo)-2-naphthol (PAN) complex in the walls of a knotted reactor, followed by an elution step using 0.50molL(-1) hydrochloric acid solution.

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