Free Standard AU & NZ Shipping For All Book Orders Over $80!
Register      Login
Environmental Chemistry Environmental Chemistry Society
Environmental problems - Chemical approaches
Shopping Cart: ( empty )
You are here: Home > Journals > EN > EN08091
RESEARCH ARTICLE
Contents Vol 6(2)

Dynamic DGT speciation analysis and applicability to natural heterogeneous complexes

Raewyn M. Town A C , Parthasarathi Chakraborty B and Herman P. van Leeuwen B
+ Author Affiliations
- Author Affiliations

A Institute for Physics and Chemistry, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark.

B Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, the Netherlands.

C Corresponding author. Email: rmt@ifk.sdu.dk

Environmental Chemistry 6(2) 170-177 https://doi.org/10.1071/EN08091
Submitted: 11 November 2008  Accepted: 10 March 2009   Published: 27 April 2009

Environmental context. The environmental fate and bioavailability of metal ions in natural waters is determined by their thermodynamic stability and kinetic features, both of which are distributed and depend on the metal ion loading of the system. Diffusive gradients in thin film (DGT) is a dynamic technique for metal speciation analysis that measures a certain portion of these complexes as determined by its operational timescale. Reliable interpretation of data furnished by DGT necessitates characterisation of its features for the particular case of heterogeneous complexes.

Abstract. Owing to their inherent heterogeneity, the thermodynamic stability of metal ion complexes with natural ligands is characterised by a distribution, and thus is a function of metal-to-ligand ratio. The kinetic features of such metal complexes are also distributed and can be probed by dynamic speciation techniques. The kinetic regime of the metal complex sample can be manipulated via the metal-to-ligand ratio, and the timescale over which kinetic parameters are actually in effect is defined by the window of the chosen technique. Here we detail the kinetic features of diffusive gradients in thin film (DGT), and show that the range of attainable measurement timescales (τ) is rather limited: variation of the gel layer thickness practically allows only one order of magnitude in τ to be scanned. The more effective use of DGT to probe the distribution of dynamic metal species in heterogeneous systems is via variation of the metal-to-ligand ratio in the sample solution. Compilation of the literature DGT data for natural waters shows that by assuming a Freundlich isotherm relationship, the degree of heterogeneity is reflected in the measured DGT concentration as a function of metal ion loading.

Additional keywords: heterogeneity, kinetic window, lability.


Acknowledgement

The authors are greatly indebted to Dr Josep Galceran (Lleida University, Spain) for his skilful comments on the theoretical background of the present work. This work was performed within the ECODIS project, funded by the European Commission’s 6th framework program, subpriority 6.3 ‘Global Change and Ecosystems’, under contract 518043.


References


[1]   Buffle J., Complexation Reactions in Aquatic Systems: an Analytical Approach 1988 (Ellis Horwood: Chichester).

[2]   M. Filella , R. M. Town , Dispelling the myths: is the existence of L1 and L2 ligands necessary to explain metal ion speciation in natural waters? Limnol. Oceanogr. 2000 , 45,  1341.
         open url image1

[3]   M. Filella , R. M. Town , Heterogeneity and lability of Pb(II) complexation by humic substances: practical interpretation tools. Fresenius J. Anal. Chem. 2001 , 370,  413.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[4]   R. M. Town , H. P. van Leeuwen , Dynamic speciation analysis of heterogeneous metal complexes with natural ligands by stripping chronopotentiometry at scanned deposition potential (SSCP). Aust. J. Chem. 2004 , 57,  983.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[5]   M. Filella , R. M. Town , Determination of metal ion binding parameters for humic substances. Part 1. Application of a simple calculation method for extraction of meaningful parameters from reverse pulse polarograms. J. Electroanal. Chem. 2000 , 485,  21.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[6]   M. T. S. D. Vasconcelos , C. A. R. Gomes , Complexation properties of natural and synthetic polymers of environmental and biological interest in presence of copper(II) at neutral pH. Eur. Polym. J. 1997 , 33,  631.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[7]   P. Chakraborty , I. I. Fasfous , J. Murimboh , C. L. Chakarabarti , Simultaneous determination of speciation parameters of Cu, Pb, Cd and Zn in model solutions of Suwannee River fulvic acid by pseudopolarography. Anal. Bioanal. Chem. 2007 , 388,  463.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[8]   G. Abate , J. C. Masini , Complexation of Cd(II) and Pb(II) with humic acids studied by anodic stripping voltammetry using differential equilibrium functions and discrete site models. Org. Geochem. 2002 , 33,  1171.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[9]   R. M. Town , M. Filella , Crucial role of the detection window in metal ion speciation analysis in aquatic systems: the interplay of thermodynamic and kinetic factors as exemplified by nickel and cobalt. Anal. Chim. Acta 2002 , 466,  285.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[10]   H. P. van Leeuwen , J. Buffle , Voltammetry of heterogeneous metal complex systems. Theoretical analysis of the effects of association/dissociation kinetics and the ensuing lability criteria. J. Electroanal. Chem. 1990 , 296,  359.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[11]   H. P. van Leeuwen , R. M. Town , J. Buffle , R. F. M. J. Cleven , W. Davison , J. Puy , W. H. van Riemsdijk , L. Sigg , Dynamic metal speciation analysis and bioavailability of metals in aquatic systems. Environ. Sci. Technol. 2005 , 39,  8545.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[12]   W. Davison , H. Zhang , In situ speciation measurements of trace components in natural waters using thin-film gels. Nature 1994 , 367,  546.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[13]   J. Salvador , J. Puy , J. Cecília , J. Galceran , Lability of complexes in steady-state finite planar diffusion. J. Electroanal. Chem. 2006 , 588,  303.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[14]   K. W. Warnken , W. Davison , H. Zhang , J. Galceran , J. Puy , In situ measurements of metal complex exchange kinetics in freshwater. Environ. Sci. Technol. 2007 , 41,  3179.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[15]   van Leeuwen H. P., Dynamic aspects of in situ speciation processes and techniques. In In Situ Monitoring of Aquatic Systems. Chemical Analysis and Speciation (Eds J. Buffle, G. Horvai) 2000, p. 253 (Wiley: Chichester).

[16]   S. Scally , W. Davison , H. Zhang , In situ measurements of dissociation kinetics and labilities of metal complexes in solution using DGT. Environ. Sci. Technol. 2003 , 37,  1379.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[17]   J. Lluís Garcés , F. Mas , J. Cecília , E. Companys , J. Galceran , J. Salvador , J. Puy , Complexation isotherms in metal speciation studies at trace concentration levels. Voltammetric techniques in environmental samples. Phys. Chem. Chem. Phys. 2002 , 4,  3764–3773.
        | Crossref | GoogleScholarGoogle Scholar |  open url image1

[18]   R. M. Town , Metal binding by heterogeneous ligands: kinetic master curves from SSCP waves. Environ. Sci. Technol. 2008 , 42,  4014.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[19]   N. J. Lehto , W. Davison , H. Zhang , W. Tych , An evaluation of DGT performance using a dynamic numerical model. Environ. Sci. Technol. 2006 , 40,  6368.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[20]   L. P. Yezek , H. P. van Leeuwen , Donnan effects in the steady-state diffusion of metal ions through charged thin films. Langmuir 2005 , 21,  10 342.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[21]   L. P. Yezek , P. L. R. van der Veeken , H. P. van Leeuwen , Donnan effects in metal speciation analysis by DET/DGT. Environ. Sci. Technol. 2008 , 42,  9250.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[22]   P. L. R. van der Veeken , J. P. Pinheiro , H. P. Leeuwen , Metal speciation by DGT/DET in colloidal complex systems. Environ. Sci. Technol. 2008 , 42,  8835.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[23]   E. R. Unsworth , K. W. Warnken , H. Zhang , W. Davison , F. Black , J. Buffle , J. Cao , R. Cleven , J. Galceran , P. Gunkel , E. Kalis , D. Kistler , Model predictions of metal speciation in freshwaters compared to measurements by in situ techniques. Environ. Sci. Technol. 2006 , 40,  1942.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[24]   H. P. van Leeuwen , R. M. Town , Stripping chronopotentiometry at scanned deposition potential (SSCP). Part 4. The kinetic current regime. J. Electroanal. Chem. 2004 , 561,  67.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[25]   J. Koutecký , J. Koryta , The general theory of polarographic kinetic currents. Electrochim. Acta 1961 , 3,  318.
        | Crossref | GoogleScholarGoogle Scholar |  open url image1

[26]   Heyrovský J., Kuta J., Principles of Polarography 1966 (Academic Press: New York).

[27]   H. P. van Leeuwen , J. Puy , J. Galceran , J. Cecília , Evaluation of the Koutecký–Koryta approximation for voltammetric currents generated by metal complex systems with various labilities. J. Electroanal. Chem. 2002 , 526,  10.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[28]   H. P. van Leeuwen , R. Cleven , J. Buffle , Voltammetric techniques for complexation measurements in natural aquatic media. Role of the size of macromolecular ligands and dissociation kinetics of complexes. Pure Appl. Chem. 1989 , 61,  255.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[29]   H. P. van Leeuwen , Kinetic classification of metal complexes in electroanalytical speciation. J. Electroanal. Chem. 1979 , 99,  93.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[30]   R. Cleven , Y. Nur , P. Krystek , G. van den Berg , Monitoring metal speciation in the rivers Meuse and Rhine using DGT. Water Air Soil Pollut. 2005 , 165,  249.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[31]   J. P. Pinheiro , A. M. Mota , M. L. S. S. Gonçalves , H. P. van Leeuwen , The pH effect in the diffusion coefficient of humic matter: influence in speciation studies using voltammetric techniques. Coll. Surf. A. Physicochem. Eng. Aspects 1998 , 137,  165.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[32]   M. Eigen , K. Tamm , Fast elementary steps in chemical reaction mechanisms. Pure Appl. Chem. 1963 , 6,  97.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[33]   J. Buffle , Z. Zhang , K. Startchev , Metal flux and dynamic speciation at (bio)interfaces. Part I: Critical evaluation and compilation of physicochemical parameters for complexes with simple ligands and fulvic/humic substances. Environ. Sci. Technol. 2007 , 41,  7609.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[34]   S. Meylan , N. Odzak , R. Behra , L. Sigg , Speciation of copper and zinc in natural freshwater: comparison of voltammetric measurements, diffusive gradients in thin films (DGT) and chemical equilibrium models. Anal. Chim. Acta 2004 , 510,  91.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[35]   N. Odzak , D. Kistler , H. Xue , L. Sigg , In situ trace metal speciation in a eutrophic lake using the technique of diffusive gradients in thin films (DGT). Aquat. Sci. 2002 , 64,  292.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[36]   W. Li , W. Zhao , P. R. Teasdale , R. John , F. Wang , Metal speciation measurement by diffusive gradients in thin films technique with different binding phases. Anal. Chim. Acta 2005 , 533,  193.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[37]   J. Salvador , J. L. Garcés , E. Companys , J. Cecília , J. Galceran , J. Puy , R. M. Town , Ligand mixture effects in metal complex lability. J. Phys. Chem. A 2007 , 111,  4304.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[38]   Zhang Z., Dynamic metal speciation in natural waters: theory, experimental validation and flux computations. 2008, PhD thesis, University of Geneva, Switzerland.

[39]   D. Alemani , J. Buffle , Z. Zhang , J. Galceran , B. Chopard , Metal flux and dynamic speciation at (bio)interfaces. Part IV: MHEDYN, a general code for metal flux computation; application to particulate complexants and their mixtures with the other natural ligands. Environ. Sci. Technol. 2008 , 42,  2028.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[40]   S. Denney , J. Sherwood , J. Leyden , In situ measurements of labile Cu, Cd and Mn in river waters using DGT. Sci. Total Environ. 1999 , 239,  71.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[41]   I. J. M. Allan , J. Knutsson , N. Guigues , G. A. Mills , A.-M. Fouillac , R. Greenwood , Evaluation of the Chemcatcher and DGT passive samplers for monitoring metals with highly fluctuating water concentrations. J. Environ. Monit. 2007 , 9,  672.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[42]   M.-H. Tusseau-Vuillemin , C. Gourlay , C. Lorgeoux , J.-M. Mouchel , R. Buzier , R. Gilbin , J.-L. Seidel , F. Elbaz-Poulichet , Dissolved and bioavailable contaminants in the Seine river basin. Sci. Total Environ. 2007 , 375,  244.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[43]   W. Li , H. Zhao , P. R. Teasdale , F. Wang , Trace metal speciation measurements in waters by the liquid binding phase DGT device. Talanta 2005 , 67,  571.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[44]   L. Sigg , F. Black , J. Buffle , J. Cao , R. Cleven , W. Davison , J. Galceran , P. Gunkel , E. Kalis , D. Kistler , M. Martin , S. Noël , Comparison of analytical techniques for dynamic trace metal speciation in natural freshwaters. Environ. Sci. Technol. 2006 , 40,  1934.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[45]   J. Gimpel , H. Zhang , W. Davison , A. C. Edwards , In situ trace metal speciation in lake surface waters using DGT, dialysis, and filtration. Environ. Sci. Technol. 2003 , 37,  138.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[46]   C. D. Luider , J. Crusius , R. C. Playle , P. J. Curtis , Influence of natural organic matter source on copper speciation as demonstrated by Cu binding to fish gills, by ion selective electrode, and by DGT gel sampler. Environ. Sci. Technol. 2004 , 38,  2865.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[47]   S. C. Apte , G. E. Batley , K. C. Bowles , P. L. Brown , N. Creighton , L. T. Hales , R. V. Hyne , M. Julli , S. J. Markich , F. Pablo , N. J. Rogers , J. L. Stauber , K. Wilde , A comparison of copper speciation measurements with the toxic responses of three sensitive freshwater organisms. Environ. Chem. 2005 , 2,  320.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[48]   A. J. Martin , R. Goldblatt , Speciation, behavior, and bioavailability of copper downstream of a mine-impacted lake. Environ. Toxicol. Chem. 2007 , 26,  2594.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[49]   H. Xue , L. Sigg , Comparison of the complexation of Cu and Cd by humic or fulvic acids and by ligands observed in lake waters. Aquat. Geochem. 1999 , 5,  313.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[50]   H. Ma , H. E. Allen , Y. Yin , Characterization of isolated fractions of dissolved organic matter from natural waters and a wastewater effluent. Water Res. 2001 , 35,  985.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[51]   M. S. Shuman , J. L. Cromer , Copper association with aquatic fulvic and humic acids. Estimation of conditional formation constants with a titrimetric anodic stripping procedure. Environ. Sci. Technol. 1979 , 13,  543.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[52]   D. T. Haworth , M. R. Pitluck , B. D. Pollard , Conditional stability constant determination of metal aquatic fulvic acid complexes. J. Liq. Chromatogr. 1987 , 10,  2877.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[53]   Y. Cao , M. Conklin , E. Betterton , Competitive complexation of trace metals with dissolved humic acid. Environ. Health Perspect. 1995 , 103,  29.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1

[54]   R. D. Guy , C. L. Chakrabarti , Studies of metal–organic interactions in model systems pertaining to natural waters. Can. J. Chem. 1976 , 54,  2600.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[55]   D. K. Ryan , J. H. Weber , Fluorescence quenching titration for determination of complexing capacities and stability constants of fulvic acid. Anal. Chem. 1982 , 54,  986.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[56]   D. Giannissis , G. Martin , Enrichissement des sediments marins en cuivre par l’intermediaire des substances humiques. Environ. Technol. Lett. 1984 , 5,  497.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[57]   E. Mansouri , M. Potin-Gautier , A. Castetbon , M. Astruc , Determination of the copper complexing capacity of dilute aqueous solutions of humic acids by D.P.A.S.V. titration in acetate buffers. Environ. Technol. 1992 , 13,  969.
        | Crossref | GoogleScholarGoogle Scholar | CAS |  open url image1

[58]   H. Itabashi , D. Yamazaki , H. Kawamoto , H. Akaiwa , Evaluation of the complexing ability of humic acids using solvent extraction technique. Anal. Sci. 2001 , 17,  785.
        | Crossref | GoogleScholarGoogle Scholar | CAS | PubMed |  open url image1




1 Note that ‘dynamic’ still includes both labile and non-labile complex systems.