Crystal seeding in flow-injection turbidimetry: determination of total sulfur in plants

Brienza, Sandra Maria Boscolo; Sartini, Raquel P.; Neto, José Anchieta Gomes; Zagatto, Elias A.G.

doi:10.1016/0003-2670(94)00249-l

Cited by 25 publications

(14 citation statements)

References 6 publications

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“…The addition of 0.1 mg L -1 of tannic acid in carrier solution improved the crystal seeding formation. 17 An auxiliary flow (AF) was needed to interface the peristaltic flow with a Ventury effect nebulizer from FAAS. 10 The proposed methodology intended to reexamine the advantages of using hemoglobin for tannin precipitation, as described by Schultz et al.…”

Section: Resultsmentioning

confidence: 99%

FIA-FAAS method for tannin determination based on a precipitation reaction with hemoglobin

Ferreira¹,

Souza²,

Nogueira³

2003

J. Braz. Chem. Soc.

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Um sistema em fluxo acoplado a espectrômetro de absorção atômica com chama (FIA-FAAS) foi desenvolvido para determinação de taninos em amostras de feijão guandu, explorando a reação de precipitação entre os taninos e proteínas. Extratos obtidos pela sonicação das amostras com solução de metanol 50% (v/v), foram introduzidos no sistema e induzidos à reação com hemoglobina, sendo o precipitado produzido pela reação retido em um filtro localizado no percurso analítico. Solução 1% (m/v) dodecil sulfato de sódio, fluindo em sentido inverso ao fluxo de filtração, foi empregado para solubilizar e conduzir o complexo tanino-hemoglobina ao detector, espectrômetro de absorção atômica com chama, para quantificação dos íons ferro presentes na estrutura da hemoglobina. Uma solução de ácido tânico foi utilizada para construção da curva analítica. O método proposto apresentou freqüência analítica de 30 amostras por hora, desvio padrão relativo de 9,7 % (n=10) e limite de quantificação 0,27 mg L -1 de ácido tânico.A flow system, coupled with flame atomic absorption spectrometry (FIA-FAAS), was developed for tannin determination in pigeon pea samples, exploring the precipitation reaction between tannins and proteins. Sample extracts obtained by sonication with a 50% (v/v) methanol solution were introduced into the system and induced to react with a hemoglobin solution. The precipitate produced was retained on a filter located in the analytical flow. A reversed flow of 1% (w/v) sodium dodecyl sulfate solution was used for solubilization of the precipitate from the filter and to conduct the tanninhemoglobin complex to the FAAS, to quantify the iron ions present in the hemoglobin structure. A tannic acid solution was used to prepare the analytical curve. The proposed method allowed determination of 30 samples per hour, a standard deviation of 9.7% (n=10), and a quantification limit of 0.27 mg L -1 for tannic acid.Keywords: tannin-protein complexes, hemoglobin, FIA, flame atomic absorption spectrometry IntroductionThe term tannin originated from "tanning", an expression which refers to tan animal skin. 1 This is possible because tannins link to collagen, which is the protein present in animal skin. 2 Thus, the ability to link and precipitate proteins is a property that defines tannins. For this reason, the reaction between tannins and protein has been used in many analytical methods for tannin determination, 3-6 especially when results that measure the correlation with the nutritional value of food are desired. 7 Moreover, this reaction is very specific, which minimizes interference effects in an analytical method.Tannin-protein complexes are dissolved by detergents, that break hydrophobic interaction between them, or by high pH values that ionize hydroxyphenolic groups so that it becomes unable to maintain the hydrogen bonding. 4 Usually tannin-protein precipitates are dissolved using sodium dodecyl sulfate. 7 Bate-Smith 6 proposed the use of hemoglobin for tannin determination as a chromoprotein in a spectrophotometric methodology...

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Section: Resultsmentioning

confidence: 99%

FIA-FAAS method for tannin determination based on a precipitation reaction with hemoglobin

Ferreira¹,

Souza²,

Nogueira³

2003

J. Braz. Chem. Soc.

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“…Because of its low solubility and the relatively slow nucleation, concentrated BaSO 4 solutions have to be used and system washing became an essential step. Recently, Brienza et al (1995) reported a different approach for the turbidimetric determination of total S in plants. This innovative system was based on precipitation with lead (Pb) and resorted to the use of crystal seeding to improve the rate of lead sulphate growth and thus achieve high sensitivity measurements with increased speed.…”

Section: Anionic Speciesmentioning

confidence: 99%

Assay of plant tissues for elemental content by flow injection analysis

Lima

Rangel

Souto

2000

Communications in Soil Science and Plant Analysis

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“…[28] This reaction was also applied by Brienza et al in the determination of total sulfur in plants using crystal seeding as an alternative approach for improving the rate of crystal growth in turbidimetric flow analysis. [29] The addition of colloid protectors or surfactants is often required and, in contrast with batch procedures, is efficiently accomplished in flow-based methodologies. These agents can be classified as aqueous solutions of mono-and polyvalent alcohols, such as glycerol, and aqueous solutions of macromolecular material, such as gelatine, various gums, or commercial preparations of surface-active agents.…”

Section: Sulfatementioning

confidence: 99%

“…[15,17 -23,25,27,31 -39] Although very fast precipitation reactions are concerned, nucleation may be a limiting factor in sample throughput. [11,29] In order to speed up nucleation, improvement of supersaturation conditions involving addition of a nucleant species (often the same as the analyte) has been performed. [29] Addition of sulfate ions into a carrier at a constant concentration or saturation of the streams with barium sulphate result in an extension of the concentration range to lower concentrations, better signal stability, and reduction of the baseline drift.…”

Section: Sulfatementioning

confidence: 99%

Turbidimetric and Nephelometric Flow Analysis: Concepts and Applications

Morais

Tóth

Rangel

2006

Spectroscopy Letters

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A review on flow analysis with turbidimetric and nephelometric detection is presented. A brief discussion of the principles of turbidimetry and nephelometry is given. Particular emphasis is devoted to coupling different flow techniques (flow injection, sequential injection, multicommutation) to these detection techniques. Applications in environmental, pharmaceutical, biological, and food samples are summarized and compared in terms of application range, flow configuration, repeatability, and sampling rate.

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Crystal seeding in flow-injection turbidimetry: determination of total sulfur in plants

Cited by 25 publications

References 6 publications

FIA-FAAS method for tannin determination based on a precipitation reaction with hemoglobin

FIA-FAAS method for tannin determination based on a precipitation reaction with hemoglobin

Assay of plant tissues for elemental content by flow injection analysis

Turbidimetric and Nephelometric Flow Analysis: Concepts and Applications

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