Weight and optical differences between soil humic acids fractions obtained by coupling SEC-PAGE

Trubetskoj, Oleg; Trubetskaya, O. E.; Reznikova, O. I.; Afanas'eva, G. V.

doi:10.1016/s0016-7061(99)00070-1

Cited by 25 publications

(10 citation statements)

References 11 publications

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“…Trubetskoj et al (1997) used size-exclusion chromatography in the presence of concentrated urea for collecting the HA fractions with different electrophoretic behavior. They have applied this method for the investigation of soil HAs (Trubetskoj et al 1997(Trubetskoj et al , 1999(Trubetskoj et al , 2010Trubetskaya et al 1997Trubetskaya et al , 2002Trubetskaya et al , 2007Trubetskaya et al , 2011Aguer et al 2001;Saiz-Jimenez et al 2006;Sanchez-Cortes et al 2006;Richard et al 2007;Francioso et al 2009). This method is advantageous because a sufficient amount of the fractions with different electrophoretic behavior could be collected for characterization.…”

Section: Infrared Spectroscopy Of the Fractionsmentioning

confidence: 99%

“…Trubetskoj et al (1997) developed a method for the fractionation of soil HAs based on the combined use of size-exclusion chromatography and PAGE in the presence of concentrated urea. They have been applying this method to the investigation of soil HAs (Trubetskaya et al 1998(Trubetskaya et al , 2002(Trubetskaya et al , 2011Trubetskoj et al 1999;Aguer et al 2001;Saiz-Jimenez et al 2006;Sanchez-Cortes et al 2006;Guyot et al 2007;Richard et al 2007;Francioso et al 2009). The advantage of this method is that it allows one to collect a sufficient amount of the fractions with different electrophoretic behavior for characterization.…”

Section: Introductionmentioning

confidence: 99%

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Fractionation of soil humic acids by preparative polyacrylamide gel electrophoresis in the presence of concentrated urea

Karim

Aoyama

2013

Soil Science and Plant Nutrition

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To separate soil humic acids (HAs) into their constituents and characterize them, polyacrylamide gel electrophoresis (PAGE) was carried out in the presence of 7 M urea using a preparative electrophoresis system. Two types of soil HAs were fractionated into nine fractions by PAGE. The dark-colored constituents were recovered from the electrophoretic fractions by precipitation on acidification, and the brown-colored constituents dissolved in the acidic solution of fast-moving fractions were recovered by adsorption onto DAX-8 resin. High-performance size-exclusion chromatography (HPSEC) confirmed that the constituents of the HAs were separated based on their molecular size by PAGE. The dark-colored constituents exhibited higher degrees of humification than did the corresponding unfractionated HAs, except for the constituents remaining in the electrophoretic gels at the end of electrophoresis. Diffuse reflectance infrared spectroscopy revealed that the chemical properties of the dark-colored constituents changed regularly: the content of carboxyl groups decreased and the proportions of proteinous, aliphatic and polysaccharide moieties increased with increasing molecular size. The humification degrees of the constituents adsorbed onto DAX-8 resin were considerably lower than those of the corresponding unfractionated HAs. The chemical properties of the DAX-8-adsorbed constituents were different from those of the dark-colored constituents. Observation of electrophoretic fractions under blue light (470 nm) and HPSEC with fluorescence detection at an excitation wavelength of 460 nm and an emission wavelength of 520 nm showed that green fluorescent substances were largely concentrated in the smallest molecular size fractions and were partitioned into both the dark-colored precipitates and DAX-8-adsorbed fractions. The proportion of organic carbon recovered by precipitation and adsorption onto DAX-8 resin was 45-63%, indicating that substantial parts of the HA constituents were missing. The unrecovered constituents were considered to be acid-soluble, nearly colorless substances. The dissociation of the acid-soluble constituents from the acid-insoluble dark-colored constituents during the preparative PAGE of soil HAs was ascribed to disruption of hydrogen bonding and hydrophobic interactions caused by concentrated urea.

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Section: Infrared Spectroscopy Of the Fractionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fractionation of soil humic acids by preparative polyacrylamide gel electrophoresis in the presence of concentrated urea

Karim

Aoyama

2013

Soil Science and Plant Nutrition

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“…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][13][14] As 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.…”

Section: Introductionmentioning

confidence: 99%

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

Moraes¹,

Rezende²

2008

J. Braz. Chem. Soc.

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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...

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“…4 In this way, three mutually uniform sub-fractions from both soil and aquatic HS (labelled A, B and C+D), differing in their electrophoretic mobility (EM) and molecular size were obtained by tandem SEC-PAGE. [5][6][7] A further optimization of the method confirmed the disaggregating effect of strong urea solution and also allowed the production of preparative quantities of sub-fractions amenable to structural analyses by more sophisticated methods. Several SEC-PAGE studies performed with soil HA fractions from different origins have already revealed clear differences in their structural compositions (aromatic, aliphatic and Ncontaining components) and chemical properties in terms of UV-visible spectra, fluorescence and photochemical activity.…”

Section: Introductionmentioning

confidence: 99%

Tandem size-exclusion chromatography-polyacrylamide gel electrophoresis fractionation of aquatic humic substances: characterization of size-separates with TMAH treatment and pyrolysis-GC/MS

Lehtonen¹,

Peuravuiori²,

Pihlaja

et al. 2008

Arkivoc

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Aquatic humic (HA) and fulvic acids (FA) from two different origins were fractionated by the tandem size-exclusion chromatography and polyacrylamide gel electrophoresis (tandem SEC-PAGE). Three HA and two FA fractions exhibited different molecular sizes, electrophoretic mobilities and structural compositions based on elemental analyses and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) after tetramethyl-ammonium hydroxide (TMAH) treatment. Based on comparison of the size-separates and unfractionated bulk samples, the highest molecular size fractions of aquatic humic substances (HS) appear to be enriched in fatty acids (mainly C 16 and C 18 ), which are strictly linked to the humic core. This and the presence of low chain fatty acids and unsaturated and di-tri acids may suggest a microbial rather than a vascular plant origin. Even if the majority of lignin derived components in aquatic HS represent relatively high state of biodegradation (oxidation), a certain variation between different sizefractions also exists, supporting a high heterogeneity and composite nature of aquatic HS. Although SEC-PAGE fractionation appears to produce fairly homogeneous HS fractions, the absorption of some urea into of the separates cannot be completely avoided in this method, which limits its suitability for evaluating, especially the presence of N-containing constituents.

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Weight and optical differences between soil humic acids fractions obtained by coupling SEC-PAGE

Cited by 25 publications

References 11 publications

Fractionation of soil humic acids by preparative polyacrylamide gel electrophoresis in the presence of concentrated urea

Fractionation of soil humic acids by preparative polyacrylamide gel electrophoresis in the presence of concentrated urea

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

Tandem size-exclusion chromatography-polyacrylamide gel electrophoresis fractionation of aquatic humic substances: characterization of size-separates with TMAH treatment and pyrolysis-GC/MS

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