Lability Criteria in Diffusive Gradients in Thin Films

Puy, Jaume; Uribe, Ramiro Restrepo; Mongin, Sandrine; Galceran, Josep; Cecília, Joan; Levy, Jacqueline L.; Zhang, Hao; Davison, William

doi:10.1021/jp212629z

Cited by 28 publications

(40 citation statements)

References 34 publications

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“…As explained elsewhere [12,13], an increase of the resin thickness increases the volume where there is net dissociation. This is true whenever partially labile complexes are present in the system, can penetrate in the resin domain and they do not reach full dissociation in the resin domain.…”

Section: Influence Of the System Parameters On The Difference Betweenmentioning

confidence: 66%

“…For labile systems (j = 1), the kinetic processes are so fast that the metal and complex are in equilibrium at any relevant spatial position in the gel, except in a layer of negligible thickness at the resin disc-diffusive gel interface (the reaction layer in the diffusive gel). For inert systems (j = 0), dissociation of the complex is so slow that the complex concentration profile in the gel domain is flat [13]. Here the system does not reach equilibrium at any position in the diffusive gel.…”

Section: The Lability Degreementioning

confidence: 99%

“…Extensions of these devices were developed for sediments and soils [4] and now, as a result of an intensive research work addressed to develop new binding agents, there are DGT devices for the accumulation of anions such as phosphate [5], non-metals and metalloids such as As, Se or Sb species, other special cations such as Hg [6] or K [7,8] and priority polar or non-polar substances [9,10]. Recently, different publications have highlighted the important role played by the resin disc thickness in determining the metal accumulation in systems with partially labile complexes [11][12][13][14][15][16]. The argument starts by assuming a fast and strong binding of the metal to the resin sites.…”

Section: Introductionmentioning

confidence: 99%

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Influence of the settling of the resin beads on diffusion gradients in thin films measurements

Jiménez-Piedrahita

Altier

Cecília

et al. 2015

Analytica Chimica Acta

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Binding resin beads used in DGT (diffusion gradients in thin films) tend to settle to one side of the resin during casting. This phenomenon might be relevant for metal accumulation when partially labile complexes dominate the metal speciation, especially after recognizing the important role played by complex dissociation in the resin domain. The influence of the inhomogeneity of the binding agent distribution on metal accumulation is here assessed by numerical simulation of DGT devices with binding beads in only one half of the resin disc, as a reasonable model of the standard resin discs. Results indicate that a decrease in mass accumulation of less than 13% can arise in these inhomogeneous devices (as compared with an ideal disc with homogeneous dispersion of the resin beads) when complexes with stability constant K<10(2)m(3)mol(-1) (K<10(5)Lmol(-1)) dominate the metal speciation. The loss increases as K increases, but the percentage of mass loss always remains lower than the volume fraction of resin disc without beads. For very labile or inert complexes, the impact of the inhomogeneous distribution of binding resin beads is negligible. As kinetic dissociation constants of complexes can be estimated from the distribution of the metal accumulation in a DGT device with a stack of two resin discs, the influence of the inhomogeneity on the recovered kinetic constant is also assessed. For the cases studied, the recovered kinetic dissociation constant, kd,recovered, retains the correct order of magnitude, being related to the true kd by kd≈f(-1)kd,recovered, quite independently of K and kd values, being f the fraction of volume of the resin disc where resin beads are dispersed.

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Section: Influence Of the System Parameters On The Difference Betweenmentioning

confidence: 66%

Section: The Lability Degreementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of the settling of the resin beads on diffusion gradients in thin films measurements

Jiménez-Piedrahita

Altier

Cecília

et al. 2015

Analytica Chimica Acta

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“…After 2 d or 6 d of deployment, the Hg DGT probes were retrieved from the sediment and thoroughly rinsed with Milli‐Q water to remove any particles attached to the probes. The deployment time (2 d for Hg(II) and 6 d for MMHg) used in the present study is much longer than the time to reach steady state (t ss ) within the diffusive gel calculated via the Einstein–Smoluchowski equation for quasi‐labile and quasi‐inert metals (10–20 min). The resin gels were extracted from the DGT probes and placed on a plastic plate in a laminar flow cabinet inside a clean room.…”

Section: Methodsmentioning

confidence: 99%

Application of diffusive gradients in thin films and core centrifugation methods to determine inorganic mercury and monomethylmercury profiles in sediment porewater

Noh

Hong

Han

2015

Enviro Toxic and Chemistry

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A diffusive gradient in thin films (DGT) is an in situ sampling technique for the quantitative analysis of contaminant concentrations that is based on the diffusion and adsorption of contaminants on to resin gels. In the present study, a DGT technique was applied to measure total mercury (Hg) and monomethylmercury (MMHg) concentrations in lake and coastal sediment porewaters and compare them with those from ex situ sediment centrifugation. To calculate the total Hg and MMHg concentrations in porewater using the DGT method, the diffusion coefficients of Hg species in a diffusive gel medium was first determined, and then total Hg and MMHg depth profiles were measured using the experimentally determined diffusion coefficients. Using the diffusion coefficients for artificial lake and estuarine waters containing inorganic salts, rather than those for lake and estuarine waters containing Suwannee River humic acid (∼5 mg C L(-1) ), the DGT method demonstrated similar Hg and MMHg profiles to those using the centrifugation method. Based on the need for fine vertical resolution and high metal concentrations to be collected, DGT is suggested to be a reliable method for determining Hg(II) and MMHg depth profiles in sediment porewater.

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“…The pores of the hydrogel and filter limit the size of the compounds that can diffuse sufficiently rapidly to contribute appreciably to the measured accumulated amount of metal . The thickness of the diffusion and resin layers provides a kinetic discrimination by limiting the time available for dissociation of metal complexes (Puy et al 2012). These properties have been exploited to study the binding of metal ions by humic substances (Scally et al 2004;Docekal et al 2005) and to interpret DGT measurements of trace metals in natural waters (Balistrieri and Blank 2008;Denney et al 1999;Gimpel et al 2003;Unsworth et al 2006;Warnken et al 2008Warnken et al , 2009.…”

Section: Introductionmentioning

confidence: 99%

Effect of Gel Interactions with Dissolved Organic Matter on DGT Measurements of Trace Metals

et al. 2014

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The technique of diffusive gradients in thin films (DGT) has emerged as a powerful technique for obtaining information on the dynamics of chemical speciation and partitioning of a diverse range of solutes in natural waters. However, there have been concerns that adsorption of dissolved organic matter (DOM) to the diffusive hydrogel could affect measurements, particularly of trace metals. Diffusive gels were exposed to solutions containing DOM from eight different sources and the adsorption of organic matter measured spectrophotometrically, both by its removal from solution and its accumulation on the gel. Both fulvic and humic acid extracted from water adsorbed slightly, but there was much more marked adsorption of humic acid extracted from a peaty soil. There was virtually no evidence of adsorption of DOM in filtered natural waters of various sources, including a lake, river and the porewaters of soils, even when the latter had high concentrations of humic substances. It appears that humic substances in solution, rather than those extractable from the solid phase of soils, do not adsorb markedly to the DGT diffusive hydrogel. DGT measurements of Cd were unaffected if their diffusive gels were pre-exposed to DOM in soil and surface waters, but DGT measurements of Cu were suppressed, especially if the pre-exposure had been to a water containing high concentrations of DOM. This effect on the DGT measurement is likely to be minimised by use of longer deployment times, but further work is required to establish the extent of such effects for a range of realistic conditions.

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Lability Criteria in Diffusive Gradients in Thin Films

Cited by 28 publications

References 34 publications

Influence of the settling of the resin beads on diffusion gradients in thin films measurements

Influence of the settling of the resin beads on diffusion gradients in thin films measurements

Application of diffusive gradients in thin films and core centrifugation methods to determine inorganic mercury and monomethylmercury profiles in sediment porewater

Effect of Gel Interactions with Dissolved Organic Matter on DGT Measurements of Trace Metals

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