Fluorescence Lifetime Measurements of Fluoranthene, 1-Naphthol, and Napropamide in the Presence of Dissolved Humic Acid

Chen, Shaojin; Inskeep, William P.; Williams, Scott A.; Callis, Patrik R.

doi:10.1021/es00058a008

Cited by 63 publications

(52 citation statements)

References 10 publications

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“…Values lay in the range 22-43 L g -1 depending on the DOM studied. In comparison, values of 91.5, 23.2 and 20.1 L (g of carbon) -1 were reported for fluoranthene, napropamide and 1-naphthol, respectively [67]. This ability of carbofuran to bind to DOM was given as an explanation for the inhibiting effect of DOM on the photolysis.…”

Section: Inhibition or Absence Of Effectmentioning

confidence: 93%

See 1 more Smart Citation

Aquatic Phototransformation of Organic Contaminants Induced by Coloured Dissolved Natural Organic Matter

Richard

Canonica

2005

The Handbook of Environmental Chemistry

129

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Section: Inhibition or Absence Of Effectmentioning

confidence: 93%

“…Using the fact that carbofuran is fluorescent, the authors determined its binding to Scheme 3 Photolysis of carbofuran in pure water DOM. They monitored the fluorescence emission intensity decay of carbofuran in solutions with various DOM concentrations, as described by Chen et al [67]. Using the relationship:…”

Section: Inhibition or Absence Of Effectmentioning

confidence: 99%

Aquatic Phototransformation of Organic Contaminants Induced by Coloured Dissolved Natural Organic Matter

Richard

Canonica

2005

The Handbook of Environmental Chemistry

129

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“…This indicated that quenching occurred. ⋅s -1 was calculated from the formula using this value of K SV and data for the HA fluorescence lifetime τ 0 ~ 3 ns [19,20]. This value was noticeably greater than the fluorescence quenching diffusion rate constant for dynamic quenching in water (~10 10 M -1 ⋅s -1 [16]).…”

Section: Modeling K Svmentioning

confidence: 99%

“…The factors (1 -10 −D 337 ) and (10 D rec ) are corrections for the effect of the internal filter during excitation and emission of fluorescence. The importance and necessity in principle of accounting for effects of the internal filter on excitation and emission were discussed earlier[16][17][18][19]. The corrected contour of the fluorescence spectrum was integrated in the range 350-650 nm (lower and upper limits for the ∫ sign).…”

mentioning

confidence: 99%

A method to study polydispersity of humic acid from fluorescence quenching by Cu2+ ions

Лаврик

Mulloev

2011

J Appl Spectrosc

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The spectral dependence of Stern-Volmer constants (K SV λ ) for fluorescence quenching by Cu 2+ ions in a standard sample of humic acid (HA) (IHSS) with monochromatic excitation (λ ex = 337.1 nm) conditions has been studied in the spectral range 400-600 nm. This is interpreted within a concept implying that HA macromolecules possess the property of polydispersity, which means that fluorophore-containing sites are different in terms of chemical nature and spatial accessibility. Modeling data show that the minimum number of spectral components required for the simulated spectral dependence of K SV λ to agree as closely as possible with that observed experimentally is three.Keywords: humic acid, polydispersity, quenching of humic acid fluorescence, Cu 2+ ion, experimental and simulated spectral dependences of Stern-Volmer constants.Introduction. Humic (HA) and fulvic (FA) acids are very important environmental components that occur in soil, water (dissolved), and air (as aerosols). HA originate in organic matter and are synthesized via oxidation of such complex natural organic molecules as carbonylhydrates, proteins, and lignins. They also occur in the remains of dead plants and animals. HA play an important role in the chemistry and transport of hydrophobic organic molecules, bioactivity, and the maintenance of the pH of natural aquifers. HA macromolecules are composed of many functionally varied chemical groups (catechins, quinones, phthalates, phenolamines, salicylates, etc.) that are capable of forming complexes [1]. Owing to these acceptor properties, HA control the concentration of dissolved pollutants (amines, phenols, heterocyclic compounds, heavy metals, etc.) [1].The following model is generally accepted for the structure of HA. There is a core (aromatic carbon skeleton) and a periphery (polysaccharide or polypeptide chain) [1]. It is assumed that the molecular fragments of the core and periphery of a single HA molecule are chemically bonded. The groups imparting specific properties to HA are the condensed aromatic rings bonded to each other through chains with somewhat conjugated C-C and other bonds. The peripheral irregular structural elements (peripheral chains) are variable components. As a result, the structures of HA molecules, even those isolated from a single soil, are not rigidly fixed and are subject to statistical fluctuations. Therefore, a characteristic feature of HA macromolecules is their polydispersity that causes an HA sample to consist of macromolecules that differ in chemical and; therefore, structural properties.Numerous physicochemical methods [1], in particular those involving fluorescence [2,3], are used to obtain information about the structural and chemical properties of HA. Fluorescence spectroscopy (fluorescence spectra, fluorescence excitation) is a non-invasive method of observation and is currently one of the most informative and common methods for studying HA structural properties [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The polydispersity of HA is manife...

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“…These values for alkaline media are at least an order of magnitude smaller than the fluorescence quenching constants for quenching of HA by doubly-charged ions of other metals [7,18]. Nevertheless, we should note that even roughly estimated absolute values of the quenching rate constants (K g = K SV /τ 0 , τ 0 is the fluorescence lifetime in the absence of the quenching agent) for τ 0 ~ 5 ns [18,19] . These values are higher than the diffusional rate constants, which means a static quenching mechanism (formation of complexes) [8].…”

mentioning

confidence: 99%

Fluorescence quenching study of the effect of association on the structure of humic acids

Лаврик

Mulloev

2010

J Appl Spectrosc

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Using as an example the concentration dependence of the fluorescence quenching constants for quenching by Cd 2+ ions for different weight fractions of humic acid, we have demonstrated the application of the fluorescence quenching method for studying the effect of association on the structure of humic acids. We have established that the quenching constants for the light fraction (5-30 kD) decrease as the humic acid concentration increases and the quenching constants increase for the heavy fraction (60-100 kD). The observed dependences are interpreted in terms of the idea of oppositely directed effects of association on the structure of the environment of fluorophores located within the core and peripheral regions of the humic acid macromolecule.Introduction. Based on our experiments studying the concentration dependences of the fluorescence spectra for different weight fractions of humic acids, we previously [1] concluded that an increase in the humic acid concentration in alkaline solution is accompanied by association of the humic acids. This conclusion was based on data from a fluorescence experiment, in which we established the presence of a long-wavelength (bathochromic) shift of the humic acid fluorescence spectrum as the humic acid concentration increased, where the spectrum consisted of two components. The long-wavelength shift of the HA fluorescence spectrum was observed both for the short-wavelength and long-wavelength components of the spectrum. The proportion of the intensity from the long-wavelength component in the total fluorescence intensity increased, while the proportion from the short-wavelength component decreased.During association, partial structural reorganization of the original humic acid macromolecule is possible. However, no information is available about the characteristic features of the change in structure of the humic acid macromolecule upon association. With the goal of obtaining additional information about the change in the structure of humic acid macromolecules upon association, we decided to use the fluorescence quenching method: the Stern-Volmer (SV) method. The proposed approach for obtaining information about the change in humic acid structure as a consequence of the effect of association essentially involves determining the concentration dependence of the fluorescence quenching constants for humic acid with some molecule (ion) as the quenching agent. Then from the shape of these curves, a conclusion is drawn about the change in accessibility of the fluorophores for quenching, i.e., about the change in the structure of the humic acid macromolecule upon association. The possibilities for using the SV method to obtain information about the structure of different types of humic acids have been shown earlier in [2][3][4][5][6][7].The SV quenching constant K T is determined from the equation

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Fluorescence Lifetime Measurements of Fluoranthene, 1-Naphthol, and Napropamide in the Presence of Dissolved Humic Acid

Cited by 63 publications

References 10 publications

Aquatic Phototransformation of Organic Contaminants Induced by Coloured Dissolved Natural Organic Matter

Aquatic Phototransformation of Organic Contaminants Induced by Coloured Dissolved Natural Organic Matter

A method to study polydispersity of humic acid from fluorescence quenching by Cu2+ ions

Fluorescence quenching study of the effect of association on the structure of humic acids

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