Use of high-resolution carbon-13 NMR to examine the enzymatic covalent binding of carbon-13-labeled 2,4-dichlorophenol to humic substances

Hatcher, Patrick G.; Bortiatynski, Jacqueline M.; Minard, Robert D.; Dec, Jerzy; Bollag, Jean Marc

doi:10.1021/es00047a015

Cited by 152 publications

(133 citation statements)

References 9 publications

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“…In addition to incorporation of highly available substrates, labeling has also been used to study the fate of xenobiotics -organic pollutants and pesticides. This has mostly been done by solution 13 C NMR, including incubation with organic matter prepared from 13 C-depleted precursors followed by silylation to increase solubility and visibility of the 13 C-labeled substrate (Haider et al 1992(Haider et al , 1993Hatcher et al 1993;Wais et al 1995Wais et al , 1996Dec and Bollag 1997;Dec et al 1997aDec et al , 1997b. There have also been a few studies using solid-state 13 C NMR to detect the bound substrate (Jurkiewicz and Maciel 1995b;Weissmahr et al 1997;Witte et al 1998;Guthrie et al 1999;Benoit and Preston 2000).…”

Section: C-13 Labeling and Xenobioticsmentioning

confidence: 99%

Carbon-13 solid-state NMR of soil organic matter - using the technique effectively

Preston¹

2001

Can. J. Soil. Sci.

112

104

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).Preston, C. M. 2001. Carbon-13 solid-state NMR of soil organic matter -using the technique effectively. Can. J. Soil Sci. 81: 255-270. Solid-state 13 C CPMAS NMR offers many options for characterizing carbon in soil organic matter (SOM). Its effectiveness, however, is often limited by a poor understanding of the techniques, and lack of hands-on access and training opportunities for students. Of nearly 250 modern NMR systems in Canada, approximately one is genuinely available for SOM studies, and there is poor communication between NMR operators and SOM users. While quantitative reliability can be addressed to some extent by multiple contact-time experiments or single-pulse (Bloch decay) spectra, it is also important to consider the effects of spectrometer background, spinning sidebands (especially with higher magnetic fields) and processing operations such as linebroadening, phasing and baseline correction. In many studies, more consideration needs to be given to instrument specifications, the type of information needed, and whether sample fractionation or pretreatment should be used. Structural information can be greatly enhanced by dipolar-dephasing and sideband suppression sequences. Sequences based on relaxation differences can reveal pools of carbon with different structures. Data analysis can be enhanced by principal component analysis, spectrum deconvolution and difference spectra. Studies of xenobiotics and C metabolism can be greatly aided by 13 C-labeling. However, a key limitation to SOM applications remains the gap in culture and expectations of the users.Key words: Soil organic matter, 13 C CPMAS NMR, Bloch decay, dipolar dephasing, spinning sidebands Preston, C. M. 2001. Analyse de la matière organique du sol par RMN au 13 C électronique -de l'importance de bien utiliser la technique. Can. J. Soil Sci. 81: 255-270. La RMN CPMAS 13 C électronique permet de caractériser le carbone présent dans la matière organique du sol (MOS) de diverses manières. Il arrive souvent cependant que cette technique perde de son efficacité parce qu'on la connaît mal et parce que les étudiants n'ont pas eu la chance de l'examiner ou de l'expérimenter. Sur les 250 systèmes modernes de RMN existant au Canada, un seul, à peu près, est vraiment réservé à l'étude de la MOS; de plus, la communication passe mal entre les opérateurs de systèmes RMN et les utilisateurs de MOS. Bien qu'on puisse remédier dans une certaine mesure au problème de la fiabilité quantitative en multipliant les expériences sur la durée de contact ou en recourant au spectre obtenu après une seule impulsion (décroissance de Bloch), il ne faut pas négliger les effets de l'arrière-plan du spectromètre, de la rotation des bandes latérales (surtout quand le champ magnétique est puissant) et des opérations de traitement comme l'élargissement des lignes, la mise en phase et la correction de la ligne de base. Dans de nombreux cas, on devrait accorder plus d'attention aux paramètres de l'instrument, au genre de données requises et à la nécessité de fractionner et...

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Section: C-13 Labeling and Xenobioticsmentioning

confidence: 99%

Carbon-13 solid-state NMR of soil organic matter - using the technique effectively

Preston¹

2001

Can. J. Soil. Sci.

112

104

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“…CDOM can act as a sensitizer for both dissolved (Zepp et al, 1985) and sorbed compounds (Fisher et al, 1987, and references therein,;Zepp et al, 1981a,b;Gauthier et al, 1986). This is of interest as a number of studies have shown that organic pollutants, including polycyclic aromatic hydrocarbons and some pesticides, extensively sorb to CDOM (McCarthy and Jimenez, 1985;Hatcher et al, 1993;Carter and Suffet, 1982;Chiou et al, 1986). To better understand the photophysics and photochemistry of these materials, and quantify CDOM sensitization of organic pollutant reactions, it is necessary to know the kinetics of both quenching and sensitization.…”

Section: Future Workmentioning

confidence: 99%

Photophysics and photochemistry of natural waters with emphasis on radical probe development and application

Herbelin¹

1994

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The work presented here consists of a literature review and calculations to estimate the importance of photochemistry to carbon cycling in the oceans, followed by a photophysical study of a series of stable nitroxide radical probes that have been used for the quantitative detection of individual carbon-centered radicals and reducing species in natural waters. Two appendices follow. The first contains preliminary experiments utilizing one of the nitroxide probes in an investigation of hydroxyl radical production rates and steadystate concentrations in seawater. The second consists of an investigation of the singlet lifetimes of humic acids (HA), in order to aid in understanding their photochemical cycling and influence on other compounds.The impact of photochemical reactions on global oceanic carbon cycling was calculated from literature values. The results indicate that between 1 and 13% of all dissolved organic carbon in the oceans is oxidized photochemically. This is a significant flux term, much larger than that of riverine input for example.A photophysical study of nitroxide radical probes was undertaken. For all of the compounds studied, steady-state absorption and fluorescence spectra were identical to those of the parent fluorophores. A decrease in fluorescence lifetime and quantum yield of tens-to hundreds-fold was observed for the paramagnetic compounds relative to their diamagnetic counterparts. Very rapid fluorescence quenching rates (3 to 80 x 1010 s-1 ) were calculated for the fluorescamine moiety of the paramagnetic nitroxide compounds in a variety of solvents. Calculated energy minimized geometries were very similar for all compounds which implies that geometric differences are not responsible for the variations found in fluorescence lifetimes and quantum yields between compounds. Calculated Firster and Dexter overlap integrals do not support deexcitation by these mechanisms. Time-resolved absorption measurements resulted in no evidence for transient species due to either intersystem crossing to the triplet state or charge transfer. Of the mechanisms considered, direct internal conversion to the ground state, is most likely given our results.An investigation of the utility of 3-(aminomethyl)-2,2,5,5-tetramethyl-1-pyrrolidinyloxy free radical (3-amp) for detection and quantification of hydroxyl radicals in natural waters found that the addition of primary probe compounds resulted in the generation of secondary carbon-centered radicals that were successfully trapped by 3-amp. Competition kinetics experiments with dimethyl sulfoxide resulted in a natural scavenger rate constant that matched previous literature results for coastal seawater. As expected, the addition of formate resulted in decreases, and the addition of nitrite in increases, in the hydroxyl radical trapping rate by this method. The resulting quantum yield values were about an order of magnitude higher than previous literature results. However, probablyI IYIIIIYYI Wilkl 4 due to the use of different latitudes at which to estimat...

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“…with CuO or RuO 4 (e.g. Hatcher et al 1993;Hyötyläinen et al 1998a). The degradation products were usually extracted, fractionated and analysed by traditional LC, GC or GC-MS.…”

Section: Introductionmentioning

confidence: 99%

“…Following, these artificial bound residues were released and characterized by selective analytical methods as described earlier (e.g. Hatcher et al 1993;Richnow et al 1998;Guthrie et al 1999). Recent reviews on the analytical topics are given by Northcott and Jones (2000), as well as Kögel-Knabner (2000).…”

Section: Introductionmentioning

confidence: 99%

Organic Contaminants in Riverine and Groundwater Systems

2006

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Use of high-resolution carbon-13 NMR to examine the enzymatic covalent binding of carbon-13-labeled 2,4-dichlorophenol to humic substances

Cited by 152 publications

References 9 publications

Carbon-13 solid-state NMR of soil organic matter - using the technique effectively

Carbon-13 solid-state NMR of soil organic matter - using the technique effectively

Photophysics and photochemistry of natural waters with emphasis on radical probe development and application

Organic Contaminants in Riverine and Groundwater Systems

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