Caracterização de ácidos húmicos de diferentes origens por eletroforese capilar de zona

Moraes, Solange Leite de; Landgraf, Mariza; Rezende, Maria Olímpia de Oliveira

doi:10.1590/s0100-46702004000200007

Cited by 4 publications

(3 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…At pH 9.3, the negative charges carried by the analytes are maximized and the acid groups carry all the negative charges. According to several authors, [18][19][20][21][22][23][24][25][26] this region is attributed to homogeneous "humic hump" in the anionic region with a distribution around an average electrophoretic mobility (AEM).…”

Section: Resultsmentioning

confidence: 99%

“…[15][16][17][18] The CE, as a method of characterizing a variety of HS, is suitable due to its polyelectrolyte properties, reflecting its charge-to-mass ratio. [19][20][21][22][23][24][25][26] The characterization of humic compounds provides important information for the evaluation of their capacity of interaction with metal ions and different classes of organic compounds as pesticides.…”

Section: -14mentioning

confidence: 99%

See 1 more Smart Citation

Capillary electrophoresis (CE): a powerful tool to characterize humic acid (HA)

Moraes¹,

Rezende²

2008

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

Neste estudo, avaliou-se a possibilidade de eliminação das etapas de purificação envolvidas na caracterização de HA. HA de diferentes fontes foram analisados por CZE apresentando diferentes eletroferogramas. Essas diferenças observadas mostram que a caracterização do HA por CZE depende da carga e do tamanho do HA. Os resultados apresentados neste trabalho sugerem que não é necessária a purificação da amostra para a caracterização de HA por CZE. Baseados nos resultados, a CZE mostrou-se uma ferramenta promissora para caracterização de HA de diferentes origens sem a etapa de purificação da amostra.The present study evaluates the possibility of eliminating the purification steps involved in the characterization of HA by capillary zone electrophoresis (CZE). The HAs of various sources were analyzed, showing different electropherograms by CZE, which depend on the charge and size of HA. The data suggest that the purification of the sample is not necessary to characterize HAs. Based on the results, CZE showed to be a promising tool to characterize HA of different origins without the purification step of the sample. Keywords: humic acid, characterization, capillary zone electrophoresis IntroductionHumic substances (HS) have an important role in the environment. They are related to the fertility of the soils, contributing to the increasing the harvest production. 1,2 In soil, HS are implicated in water-holding capacity, pH buffering, ion exchange, binding of metal ions and hydrophobic compounds. [3][4][5][6] These substances are classified into three groups, humic acids (HAs), fulvic acids (FAs) and humins, on the basis of their solubility in acidic and basic solutions. [7][8][9] HAs present relatively high molecular mass polyelectrolytes containing aromatic, aliphatic and heterocyclic subunits.10 Their chemical structure is less known due to the origin and the natural conditions prevailing during their formation. 11 The degree of ionization of these macromolecules is governed by the amount of ionized phenolic and carboxylic groups of HAs, which is a function of solution pH. 12-14As a modern analytical technique, capillary electrophoresis (CE) has become an attractive method for the characterization of molecules with high structural complexity and wide range of molecular weights, such as HA. [15][16][17][18] The CE, as a method of characterizing a variety of HS, is suitable due to its polyelectrolyte properties, reflecting its charge-to-mass ratio. [19][20][21][22][23][24][25][26] The characterization of humic compounds provides important information for the evaluation of their capacity of interaction with metal ions and different classes of organic compounds as pesticides. 25Some valuable features of this analytical technique are short analysis time, selectivity for the analytes, simple analytical procedure, and micro-quantity consumption of samples. In CZE, the introduction of samples is carried out at the anode, while the detection is realized at the cathode. Ionic species are separated based on their charge and si...

show abstract

Section: Resultsmentioning

confidence: 99%

Section: -14mentioning

confidence: 99%

Capillary electrophoresis (CE): a powerful tool to characterize humic acid (HA)

Moraes¹,

Rezende²

2008

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

show abstract

“…Analisando os dados tratados, foram determinadas cinco classes de grupos tituláveis, compatí-veis com os resultados da literatura com relação a substâncias húmicas [13,14], sendo HA 1 , HA 2 e HA 3 , as três primeiras (pK < 7), tituladas em uma região de pH típica para grupamentos carboxílicos e as duas últimas, HA 4 e HA 5 (pK > 7), atribuídas a grupamentos fenólicos. Os três primeiros valores médios de pK a encontrados foram próprios para grupos carboxílicos.…”

Section: Tabelaunclassified

Características físico-químicas de ácidos húmicos em diferentes etapas da vermicompostagem

Brighenti

Reis

2010

Eclet. Quim.

View full text Add to dashboard Cite

Samples of materials, collected at different stages of vermicompostaging, were submitted to extraction procedures of humic acids. Titration, termogravimetry (DTG), X-ray diffraction, spectrophotometry in the uv/visible and infrared techniques, were used in the study of these materials. The data from the potentiometry titration analysis were submitted to adjustment by non-linear regression, determining thus five values of pKa’s characteristic of five classes of titrable groups. In the DTG curves two stages can be observed, being the firstone characteristic of the separation of aliphatic and/or alycyclic structures and the second of decomposition of aromatic structures. The X-ray diffraction technique exhibed marked differences in the results, mainly in the first three peaks, were a structural reorganization and a polymerization along the vermicompostaging process. The infrared spectra practically no differentiation between the samples. The values for the ratio E4/E6 found are in accordance with the characteristic values for humic acids, but do not supply information that can contribute to the elucidation of the structure and formation of these acids.

show abstract

Interactions fulvate-metal (Zn2+, Cu2+ and Fe2+): theoretical investigation of thermodynamic, structural and spectroscopic properties

et al. 2016

View full text Add to dashboard Cite

The use of theoretical calculation to determine structural properties of fulvate-metal complex (zinc, copper and iron) is here related. The species were proposed in the ratio 1:1 and 2:1 for which the molecular structure was obtained through the semi-empirical method PM6. The calculation of thermodynamic stability ([Formula: see text]) predicted that the iron complex were more exo-energetic. Metallic ions were coordinated to the phtalate groups of the model-structure of fulvic acid Suwannee River and the calculations of vibrational frequencies suggested that hydrogen bonds may help on the stability of the complex formation.

show abstract

Caracterização de ácidos húmicos de diferentes origens por eletroforese capilar de zona

Cited by 4 publications

References 14 publications

Capillary electrophoresis (CE): a powerful tool to characterize humic acid (HA)

Capillary electrophoresis (CE): a powerful tool to characterize humic acid (HA)

Características físico-químicas de ácidos húmicos em diferentes etapas da vermicompostagem

Interactions fulvate-metal (Zn2+, Cu2+ and Fe2+): theoretical investigation of thermodynamic, structural and spectroscopic properties

Contact Info

Product

Resources

About