Selective binding of Cd<sup>2+</sup>by natural and synthetic organic macromolecules investigated by<sup>113</sup>Cd‐NMR spectroscopy

Chung, Kun Ho; Moon, Christina H.

doi:10.1080/09593339409385485

Cited by 8 publications

(2 citation statements)

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“…Cadmium-113 NMR has been used in a few studies of cadmium binding by solid-phase environmental samples ( − ). This method has also been applied to study cadmium binding by dissolved organic matter, including Suwannee River NOM ( − ), Suwannee River fulvic acid (), and a soil fulvic acid ().…”

Section: Introductionmentioning

confidence: 99%

Using Cadmium-113 NMR Spectrometry To Study Metal Complexation by Natural Organic Matter

Perdue

Gelbaum

1998

Environ. Sci. Technol.

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Because of its relatively high natural abundance and the broad range of chemical shifts (900 ppm), 113Cd is a potentially excellent istope for NMR studies of metal binding sites of natural organic matter (NOM). This paper presents a 113Cd NMR study of the effects of pH and, to a lesser extent, Cd/C molar ratio on the complexation of cadmium ion by Suwannee River NOM. Spectra are presented for solutions ranging in pH from 3.6 to 9.0 and ranging in Cd/C ratio from 0.0013 to 0.0068. At acidic pH, a single somewhat sharp peak is observed, but more complex spectra are obtained at alkaline pH. These changes indicate that Cd−NOM exchange rates are much faster at acidic pH, where the concentration of free Cd2+ is greatest. Under nearly all the conditions of Cd/C ratio and pH that were used, Cd2+ is primarily coordinated by O donor atoms, probably in carboxyl groups. At high pH, some evidence of Cd2+ coordination by N donor atoms is observed. No evidence of Cd2+ ions coordinated by S donor atoms was observed in the NMR spectra, even at Cd/C ratios that were significantly lower than the S/C ratio of the NOM.

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Section: Introductionmentioning

confidence: 99%

Using Cadmium-113 NMR Spectrometry To Study Metal Complexation by Natural Organic Matter

Perdue

Gelbaum

1998

Environ. Sci. Technol.

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“…The observation that nearly all complexation of Cd 2+ involves O-ligands, for example, is an inescapable consequence of conducting 113 Cd NMR experiments at a Cd/C molar ratio that exceeds the N/C and S/C ratios of the NOM. Of the published results that are known to the authors, ,,− at least half of the measurements were made under such conditions. Specifically, Cd/C ratios were so high that Cd/N ratios were greater than one in 50% of the experiments, and Cd/S ratios were greater than one in 92% of the measurements.…”

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confidence: 99%

A Potentiometric and ¹¹³Cd NMR Study of Cadmium Complexation by Natural Organic Matter at Two Different Magnetic Field Strengths

2004

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The binding of cadmium to Suwannee River natural organic matter (NOM) has been investigated across a broad range of Cd/C ratios (0.00056-0.0056) and pH values (3.5-11) by (113)Cd NMR spectroscopy at two magnetic field strengths (B(0) = 9.4 and 11.7 T). Caused by the very peculiar and highly complex nature of the Cd-NOM exchanging system, these (113)Cd NMR spectra are characterized by a pH- and concentration-dependent superposition of slow, intermediate, and fast chemical exchange. The complex interplay of solution chemistry and chemical exchange requires a thorough mapping of this Cd-NOM chemically exchanging system through NMR acquisition at two magnetic field strengths and a systematic variation of Cd/C ratios and pH values. The interpretation of (113)Cd NMR spectra is greatly facilitated and constrained by simultaneous measurements of pH and pCd, which allows a model-independent calculation of organically bound Cd(2+) under all experimental conditions. Within the range of chemical conditions applied in this study, (113)Cd NMR spectrometric evidence is consistent with coordination of cadmium by oxygen, nitrogen, and sulfur ligands in NOM. Under all experimental conditions, cadmium is primarily coordinated to oxygen; however, several lines of evidence point to the participation of nitrogen ligands, even in acidic solutions where nitrogen ligands are primarily bound to protons. Under alkaline conditions, up to one-third of cadmium may be coordinated to nitrogen, and a small, but unquantifiable, percentage of cadmium is coordinated to sulfur ligands, as evidenced by far-low-field (113)Cd NMR resonances.

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Metals in the Environment

Sutrisno

Simpson

1996

eMagRes

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Selective binding of Cd²⁺by natural and synthetic organic macromolecules investigated by¹¹³Cd‐NMR spectroscopy

Cited by 8 publications

References 4 publications

Using Cadmium-113 NMR Spectrometry To Study Metal Complexation by Natural Organic Matter

Using Cadmium-113 NMR Spectrometry To Study Metal Complexation by Natural Organic Matter

A Potentiometric and ¹¹³Cd NMR Study of Cadmium Complexation by Natural Organic Matter at Two Different Magnetic Field Strengths

Metals in the Environment

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Selective binding of Cd2+by natural and synthetic organic macromolecules investigated by113Cd‐NMR spectroscopy

Cited by 8 publications

References 4 publications

Using Cadmium-113 NMR Spectrometry To Study Metal Complexation by Natural Organic Matter

Using Cadmium-113 NMR Spectrometry To Study Metal Complexation by Natural Organic Matter

A Potentiometric and 113Cd NMR Study of Cadmium Complexation by Natural Organic Matter at Two Different Magnetic Field Strengths

Metals in the Environment

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Selective binding of Cd²⁺by natural and synthetic organic macromolecules investigated by¹¹³Cd‐NMR spectroscopy

A Potentiometric and ¹¹³Cd NMR Study of Cadmium Complexation by Natural Organic Matter at Two Different Magnetic Field Strengths