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Direct spectroscopic speciation of the complexation of U(VI) in acetate solution.

Meinrath G, Kwiatek D, Hnatejko Z, Lis S - Monatsh. Chem. (2014)

Bottom Line: Using chemometric data analysis, the resulting factor structure was evaluated to obtain a subset of 14 spectra holding only one coordinated species next to UO2 (2+) (aq).The molar absorption coefficient for the U(VI) monoaceto species was estimated as ε 418 = 17.8 ± 1 dm(3) mol(-1) cm(-1).Spectral deconvolution was used to obtain an estimate of the species concentrations which allowed to calculate for each sample the free acetate concentration, the total U(VI) amount and, eventually, to estimate the formation quotient lg β 11 = 2.8 ± 0.3 of UO2(CH3COO)(+).

View Article: PubMed Central - PubMed

Affiliation: RER Consultants, Fuchsbauerweg 50, 94036 Passau, Germany.

ABSTRACT

Abstract: As a result of systematic UV-Vis absorption spectroscopy studies in the U(VI) acetate system, the single component spectrum of [UO2CH3COO](+) with characteristic parameters was evaluated and applied in quantitative deconvolution of multicomponent spectra. Free acetate concentrations were obtained by the use of geochemical and probabilistic modelling codes. A total of 51 UV-Vis spectra were collected in a wide range of experimental conditions where coordination of U(VI) by acetate ion was indicated by characteristic variations in the spectra structure as compared to UO2 (2+). Using chemometric data analysis, the resulting factor structure was evaluated to obtain a subset of 14 spectra holding only one coordinated species next to UO2 (2+) (aq). The molar absorption coefficient for the U(VI) monoaceto species was estimated as ε 418 = 17.8 ± 1 dm(3) mol(-1) cm(-1). Spectral deconvolution was used to obtain an estimate of the species concentrations which allowed to calculate for each sample the free acetate concentration, the total U(VI) amount and, eventually, to estimate the formation quotient lg β 11 = 2.8 ± 0.3 of UO2(CH3COO)(+).

No MeSH data available.


Related in: MedlinePlus

Graphical representation of the SCREE test. The first factor explains about 85 % of the experimental variance, the second about 7 %. The subsequent factors are not able to remove significant parts of the remaining variance
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Fig3: Graphical representation of the SCREE test. The first factor explains about 85 % of the experimental variance, the second about 7 %. The subsequent factors are not able to remove significant parts of the remaining variance

Mentions: From a total of 51 spectra collected at random in a wider range of conditions, 51 indicated coordinated U(VI) due to significant difference of the observed UV–Vis absorption spectrum from the well-known spectrum of UO22+. From these 51 spectra, a set of spectra had to be found holding only UO22+ and one further component. A larger number of spectra could readily be eliminated for their physico-chemical state suggesting either influence of hydrolysis or formation of higher U(VI) acetato species. The remaining spectra were selected by either submatrix analysis [33] or computer-assisted target factor analysis (CAT) [34]. Thus, a data set with 14 spectra was obtained with the resulting factor structure given as a SCREE test [35] in Fig. 3. The first factor alone explains more than 90 % of the observed variance. The second factor explains just 7 % of the variance—that is the additional signal caused by the hyperchromic shift due to coordination by acetate.Fig. 3


Direct spectroscopic speciation of the complexation of U(VI) in acetate solution.

Meinrath G, Kwiatek D, Hnatejko Z, Lis S - Monatsh. Chem. (2014)

Graphical representation of the SCREE test. The first factor explains about 85 % of the experimental variance, the second about 7 %. The subsequent factors are not able to remove significant parts of the remaining variance
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4495045&req=5

Fig3: Graphical representation of the SCREE test. The first factor explains about 85 % of the experimental variance, the second about 7 %. The subsequent factors are not able to remove significant parts of the remaining variance
Mentions: From a total of 51 spectra collected at random in a wider range of conditions, 51 indicated coordinated U(VI) due to significant difference of the observed UV–Vis absorption spectrum from the well-known spectrum of UO22+. From these 51 spectra, a set of spectra had to be found holding only UO22+ and one further component. A larger number of spectra could readily be eliminated for their physico-chemical state suggesting either influence of hydrolysis or formation of higher U(VI) acetato species. The remaining spectra were selected by either submatrix analysis [33] or computer-assisted target factor analysis (CAT) [34]. Thus, a data set with 14 spectra was obtained with the resulting factor structure given as a SCREE test [35] in Fig. 3. The first factor alone explains more than 90 % of the observed variance. The second factor explains just 7 % of the variance—that is the additional signal caused by the hyperchromic shift due to coordination by acetate.Fig. 3

Bottom Line: Using chemometric data analysis, the resulting factor structure was evaluated to obtain a subset of 14 spectra holding only one coordinated species next to UO2 (2+) (aq).The molar absorption coefficient for the U(VI) monoaceto species was estimated as ε 418 = 17.8 ± 1 dm(3) mol(-1) cm(-1).Spectral deconvolution was used to obtain an estimate of the species concentrations which allowed to calculate for each sample the free acetate concentration, the total U(VI) amount and, eventually, to estimate the formation quotient lg β 11 = 2.8 ± 0.3 of UO2(CH3COO)(+).

View Article: PubMed Central - PubMed

Affiliation: RER Consultants, Fuchsbauerweg 50, 94036 Passau, Germany.

ABSTRACT

Abstract: As a result of systematic UV-Vis absorption spectroscopy studies in the U(VI) acetate system, the single component spectrum of [UO2CH3COO](+) with characteristic parameters was evaluated and applied in quantitative deconvolution of multicomponent spectra. Free acetate concentrations were obtained by the use of geochemical and probabilistic modelling codes. A total of 51 UV-Vis spectra were collected in a wide range of experimental conditions where coordination of U(VI) by acetate ion was indicated by characteristic variations in the spectra structure as compared to UO2 (2+). Using chemometric data analysis, the resulting factor structure was evaluated to obtain a subset of 14 spectra holding only one coordinated species next to UO2 (2+) (aq). The molar absorption coefficient for the U(VI) monoaceto species was estimated as ε 418 = 17.8 ± 1 dm(3) mol(-1) cm(-1). Spectral deconvolution was used to obtain an estimate of the species concentrations which allowed to calculate for each sample the free acetate concentration, the total U(VI) amount and, eventually, to estimate the formation quotient lg β 11 = 2.8 ± 0.3 of UO2(CH3COO)(+).

No MeSH data available.


Related in: MedlinePlus