Fluorescence quenching titration for determination of complexing capacities and stability constants of fulvic acid

Ryan, David K.; Weber, James H.

doi:10.1021/ac00243a033

Cited by 345 publications

(296 citation statements)

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“…Fluorescence spectroscopy is a simple, sensitive, and nondestructive analytical technique that has the potential to provide invaluable information about the molecular structure, functionalities, and conformation and intramolecular and intermolecular interactions of DOM with proton and metal ions [1,8,9]. Early studies used single excitation and emission wavelengths, which are typical of humic-like fluorophores [8,[10][11][12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…Early studies used single excitation and emission wavelengths, which are typical of humic-like fluorophores [8,[10][11][12][13][14][15][16]. Fluorescence excitation-emission matrix (EEM) spectroscopy can measure emission spectra across a range of excitation wavelengths and provide an overall view of all the features that exist within a selected spectral range.…”

Section: Introductionmentioning

confidence: 99%

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Study of the pH influence on the optical properties of dissolved organic matter using fluorescence excitation–emission matrix and parallel factor analysis

Yan

et al. 2013

Journal of Luminescence

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a b s t r a c tThis study investigated the optical properties of dissolved organic matter (DOM) using the fluorescence excitation-emission matrix (EEM) method combined with parallel factor (PARAFAC) analysis. The examined DOM samples included Suwannee River fulvic acid (SRFA) and Nordic Reservoir natural organic matter (NRNOM). The optical properties of the DOM were determined from the behavior of individual groups of DOM fluorophores responding to different ionization states. The PARAFAC examination revealed that there were six independent EEM components in the SRFA that behaved differently in terms of pH influence on their fluorescence intensity. The dominant EEM peak locations (λ ex /λ em ) of these components were (

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study of the pH influence on the optical properties of dissolved organic matter using fluorescence excitation–emission matrix and parallel factor analysis

Yan

et al. 2013

Journal of Luminescence

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“…The AHS interaction with metal species cause, frequently, a quenching of initial fluorescence intensity. 37,38 With some metals this interaction can also promote an increase of fluorescence signal, as noted for aluminum. 39 Complexation capacity studies made in this work showed that fluorescence intensity grows with an increase of the quantities of Al 3+ .…”

Section: Fluorescence Spectramentioning

confidence: 89%

“…[20][21][22] Among them molecular fluorescence has been one of the techniques used in many works to characterize AHS, [23][24][25][26] as well as studies of complexation with metal ions. [27][28][29] The fluorescence has advantages over others, such as nuclear magnetic resonance (NMR) which is also widely used in AHS studies.…”

Section: Introductionmentioning

confidence: 99%

“…33,34 The fluorescence excitationemission matrix (EEM) is a tool that allows to obtain better information on the existence of fluorophores and consequently on the chemical structure of AHS. 35 Several authors have demonstrated that metals are responsible to quench the fluorescence signal, [36][37][38] but in some cases it is possible to increase it. 39 In cases of quenching of the fluorescence signals is possible to determine the conditional stability constant (K C ) of AHS-metal complex using the Stern-Volmer model.…”

Section: Introductionmentioning

confidence: 99%

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Solar radiation effect on the complexation capacity of aquatic humic substances with metals

Melo

Toffoli

Moreira

et al. 2012

J. Braz. Chem. Soc.

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Este estudo teve como principal objetivo avaliar o efeito da radiação solar sobre a capacidade de complexação das substâncias húmicas aquáticas (AHS) com as espécies metálicas Al 3+ , Cr 3+ , CrO 42-e Ni 2+ . Microcosmos foram montados com AHS extraídas do Rio Preto com concentração de 5,0 mg L -1 de carbono orgânico dissolvido e diferentes concentrações de metais, sendo expostos à radiação solar in situ. As constantes de estabilidade condicional foram de 2,0 × 10 -2 , 1,1 × 10 -5 e 2,6 × 10 -2 para os complexos AHS-Cr 3+ , AHS-Ni 2+ e AHS-CrO 4 2-, respectivamente. Os resultados mostraram que a radiação solar foi responsável por um decréscimo na capacidade de complexação de 15-26% para AHS-Al 3+ , 15-72% para AHS-Cr 3+ , 12-18% para AHS-CrO 4 2-e de 13-42% para AHS-Ni 2+ . Conclui-se que a radiação solar altera a disponibilidade de metais previamente complexados às AHS, tornando-os disponíveis no corpo aquático.This study had as main objective to assess the effect of solar radiation on the capacity of the aquatic humic substances (AHS) to complex Al 3+ , Cr 3+ , CrO 4 2-and Ni 2+ . Microcosms were prepared with AHS from Preto River containing 5.0 mg L -1 of dissolved organic carbon and different concentrations of metal species, being exposed to solar radiation, in situ. Conditional stability constants obtained for the AHS-Cr 3+ , AHS-Ni 2+ and AHS-CrO 4 2-complexes were 2.0 × 10 -2 , 1.1 × 10 -5 and 2.6 × 10 -2 , respectively. The results showed that solar radiation is responsible for decreasing capacity complexation in 15-26% for AHS-Al 3+ , 15-72% for AHS-Cr 3+ , 12-18% for AHS-CrO 4 2-and 13-42% for AHS-Ni 2+ . We can conclude that solar radiation alters metals' availability previously complexed to AHS, making them available in the aquatic body.Keywords: aquatic humic substances, metal complexation, solar radiation, fluorescence IntroductionAquatic humic substances (AHS) have been intensively studied because they play an essential role in biogeochemical processes. 1,2 They can participate in the complexation reactions with metal ions thereby influencing the transport and availability of them in the environment, 2-4 may suffer interactions with organic compounds and thus, reduce or increase its toxicity to the biota, 4,5 can act in redox 6 and photochemical reactions. 7 Aquatic HS are products of the decomposition of vegetal and animal remains from microbiological transformations. They are normally dark colored organic macromolecules with a high molecular weight, a complex structure consisting of aromatic and aliphatic compounds, which have a large number of functional groups containing oxygen, e.g., carboxylates (-COOH), phenolics (aromatics-OH), alcoholics (-OH), quinones (aromatics=O), among others. 1,2 Depending on the water solubility, AHS can be operationally separated into three fractions: fulvic acids that are soluble in all pH range, humic acids that are soluble in alkaline pH and insoluble in acid pH, and humin that is insoluble in all pH range. It is worth noting that the AHS comprise about 40-60% ...

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EPR, FTIR, Raman, UV–Visible Absorption, and Fluorescence Spectroscopies in Studies of NOM

Martin‐Neto

Milori

Silva

et al. 2009

Biophysico‐Chemical Processes Involving Natural Nonliving Organic Matter in Environmental Systems

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Fluorescence quenching titration for determination of complexing capacities and stability constants of fulvic acid

Cited by 345 publications

References 25 publications

Study of the pH influence on the optical properties of dissolved organic matter using fluorescence excitation–emission matrix and parallel factor analysis

Study of the pH influence on the optical properties of dissolved organic matter using fluorescence excitation–emission matrix and parallel factor analysis

Solar radiation effect on the complexation capacity of aquatic humic substances with metals

EPR, FTIR, Raman, UV–Visible Absorption, and Fluorescence Spectroscopies in Studies of NOM

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