Strategies in the application of the Donnan membrane technique

2011 ◽  
Vol 8 (5) ◽  
pp. 466 ◽  
Author(s):  
Liping Weng ◽  
Flora Alonso Vega ◽  
Willem H. Van Riemsdijk
Keyword(s):  
Ion Concentration ◽  
Accumulation Factor ◽  
Analytical Technique ◽  
Ion Concentrations ◽  
Icp Ms ◽  
Membrane Technique ◽  
Free Ion ◽  
Cell Measurement ◽  
Donnan Membrane Technique ◽  
Measurement Strategies

Environmental context Free ion concentrations determine the effects of nutrients and pollutants on organisms in the environment. The Donnan membrane technique provides a measure of free ion concentrations. This paper presents clear guidelines on the application of the Donnan membrane technique for determining free ion concentrations in both synthetic and natural samples. Abstract The Donnan membrane technique (DMT) can be applied to measure free ion concentrations both in laboratory and in situ in the field. In designing DMT experiments, different strategies can be taken, depending on whether accumulation is needed. (1) When the free ion concentration is above the detection limit of the analytical technique (e.g. ICP-MS), no accumulation is needed and no ligand is added to the acceptor. Measurement can be based on the Donnan membrane equilibrium. (2) When an accumulation of less than 500 times is needed, an appropriate amount of ligand can be added to the acceptor and measurement can be based on the Donnan membrane equilibrium. (3) When an accumulation factor of larger than 500 times is needed, a relatively large amount of ligand is added to the acceptor and measurement can be based on the transport kinetics. In this paper, several issues in designing the DMT experiments are discussed: choice of DMT cell, measurement strategies and ligands and possible implication of slow dissociation of metal complexes in the sample solution (lability issue). The objective of this paper is to give better guidance in the application of DMT for measuring free ion concentrations in both synthetic and natural samples.

Measuring Free Metal Ion Concentrations in Situ in Natural Waters Using the Donnan Membrane Technique

2006 ◽  
Vol 40 (3) ◽  
pp. 955-961 ◽  
Author(s):  
Erwin J. J. Kalis ◽  
Weng ◽  
Freerk Dousma ◽  
Erwin J. M. Temminghoff ◽  
Willem H. Van Riemsdijk
Keyword(s):  
Metal Ion ◽  
Natural Waters ◽  
Ion Concentrations ◽  
Membrane Technique ◽  
Donnan Membrane Technique ◽  
Free Metal ◽  
Free Metal Ion

Measuring Free Metal Ion Concentrations in Multicomponent Solutions Using the Donnan Membrane Technique

2007 ◽  
Vol 79 (4) ◽  
pp. 1555-1563 ◽  
Author(s):  
Erwin J. J. Kalis ◽  
Weng ◽  
Erwin J. M. Temminghoff ◽  
Willem H. van Riemsdijk
Keyword(s):  
Metal Ion ◽  
Ion Concentrations ◽  
Membrane Technique ◽  
Donnan Membrane Technique ◽  
Multicomponent Solutions ◽  
Free Metal ◽  
Free Metal Ion

scholarly journals Assessing WHAM/Model VII against field measurements of free metal ion concentrations: model performance and the role of uncertainty in parameters and inputs

2011 ◽  
Vol 8 (5) ◽  
pp. 501 ◽  
Author(s):  
Stephen Lofts ◽  
Edward Tipping
Keyword(s):  
Metal Ion ◽  
Chemical Speciation ◽  
Model Performance ◽  
Model Parameters ◽  
Analytical Technique ◽  
Ion Concentrations ◽  
Model Predictions ◽  
Free Ion ◽  
Free Metal ◽  
Free Metal Ion

Environmental contextThe chemical speciation of metals in waters is of great importance in determining their transport, fate and effects in the environment. Modelling chemical speciation is valuable for making predictions about these effects. Here a model of metal speciation is tested against field data, and recommendations are made as to how both model and measurements might be improved in future. AbstractA key question in the evaluation of chemical speciation models is: how well do model predictions compare against speciation measurements? To address this issue, the performance of WHAM/Model VII in predicting free metal ion concentrations in field samples has been evaluated. A statistical sampling method considering uncertainties in input measurements, model parameters and the binding activity of dissolved organic matter was used to generate distributions of predicted free ion concentrations. Model performance varied with the metal considered and the analytical technique used to measure the free ion. Generally, the best agreement between observation and prediction was seen for aluminium, cobalt, nickel, zinc and cadmium. Important differences in agreement between model and observations were seen, depending upon the analytical technique. In particular, concentrations of free ion determined with voltammetric techniques were largely over-predicted by the model. Uncertainties in model predictions varied among metals. Only for aluminium could discrepancies between observation and model could be explained by uncertainties in input measurements and model parameters. For the other metals, the ranges of model predictions were mostly too small to explain the discrepancies between model and observation. Incorporating the effects of uncertainty into speciation model predictions allows for more rigorous assessment of model performance.

In situ Fe isotopic analyses of fourteen reference materials using a synthetic Cr standard for mass bias and isobaric interference corrections by femtosecond LA-MC-ICP-MS

2021 ◽  
Author(s):  
Lei Xu ◽  
Wen Zhang ◽  
Tao Luo ◽  
Jin-Hui Yang ◽  
Zhaochu Hu
Keyword(s):  
Reference Materials ◽  
Isotope Ratios ◽  
Isobaric Interference ◽  
Analytical Technique ◽  
Mass Bias ◽  
Icp Ms ◽  
Isotopic Analyses

High precise and accurate measurements of Fe isotope ratios for fourteen reference materials from the USGS, MPI-DING and CGSG were successfully carried out using a developed analytical technique by fs...

Thermal stability of ribosomes from a thermophilic and a mesophilic fungus

1973 ◽  
Vol 19 (6) ◽  
pp. 761-763 ◽  
Author(s):  
H. M. Miller ◽  
M. G. Shepherd
Keyword(s):  
Thermal Stability ◽  
Ion Concentration ◽  
Magnesium Ion ◽  
Penicillium Notatum ◽  
Ribosomal Subunits ◽  
Ion Concentrations ◽  
Thermal Stability Of

Ribosomes and ribosomal subunits from the thermophile Penicillium duponti were found to be more thermostable than the corresponding particles from the mesophile Penicillium notatum. The thermostability of the ribosomes from both organisms was dependent on magnesium ion concentration. The dissociation of the 80-S ribosomes into 60-S and 40-S subunits occurred at higher magnesium ion concentrations for the mesophile than the thermophile.

scholarly journals Free Eu(III) Determination by Donnan Membrane Technique with Electrochemical Detection: Implementation and Evaluation

2021 ◽  
Author(s):  
Noémie Janot ◽  
Jan E. Groenenberg ◽  
Alba Otero-Fariña ◽  
José Paulo Pinheiro
Keyword(s):  
Cation Exchange ◽  
Natural Waters ◽  
Stripping Voltammetry ◽  
Cation Exchange Membrane ◽  
Membrane Technique ◽  
Ligand Free ◽  
Natural Solution ◽  
Pass Through ◽  
Donnan Membrane Technique ◽  
Exchange Membrane

AbstractThe aim of this study was to develop an analytical method to determine free concentrations of Europium (Eu(III)) in natural waters. Europium(III) in solution was detected using cathodic stripping voltammetry after complexation with N-nitroso-N-phenylhydroxylamine (cupferron). Optimization of analytical parameters allowed us to detect nanomolar levels of Eu(III) in solution. Free Eu(III) in solution was measured using the Donnan membrane technique in which a natural solution (the “donor”, containing various ligands) is separated from a ligand-free solution (the “acceptor”) by a cation-exchange membrane. This membrane allows only non-colloidal cationic species to pass through it, and after an adequate time equilibrium is reached between both compartments. Total Eu(III) concentration can then be quantified in the acceptor solution and related to free Eu(III) in the natural sample. Due to its high valency, free Eu(III) tends to adsorb strongly to the cation-exchange membrane. In order to determine the physicochemical conditions minimizing this adsorption, we analyzed solutions of different Eu(III) and Ca(II) (as background ion) concentrations. Results showed that 100 mM of Ca(II) were necessary to make adsorption of Eu(III) onto the membrane negligible. The optimized setup was then used to quantify Eu(III) complexation in a Eu(III)-dissolved organic matter solution.

Inorganic mass spectrometry

2018 ◽  
Vol 4 (3) ◽  
Author(s):  
Josefina Pérez-Arantegui ◽  
Francisco Laborda
Keyword(s):  
Mass Spectrometry ◽  
High Precision ◽  
Mass Spectrometric ◽  
Sample Introduction ◽  
Mass Separation ◽  
Analytical Technique ◽  
Good Spatial Resolution ◽  
Icp Ms ◽  
Analytical Properties ◽  
Mass Spectrometric Techniques

Abstract Inorganic mass spectrometry has been used as a well-known analytical technique to determine elemental/isotopic composition of very diverse materials, based on the different mass-to-charge ratios of the ions produced in a specific source. In this case, two mass spectrometric techniques are explained and their analytical properties discussed: inductively coupled plasma mass spectrometry (ICP-MS) and thermal ionisation mass spectrometry (TIMS), since they are the most used in art and archaeological material studies. Both techniques combine advantageous analytical properties, like low detection limits, low interferences and high precision. The use of laser ablation as sample introduction system in ICP-MS allows to avoid sample preparation and to perform good spatial-resolution analysis. The development of new instruments, improving the mass separation and the detection of the ions, specially multicollection detectors, results in high-precision isotopic analysis. A summary of the important applications of these mass spectrometric techniques to the analysis of art and archaeological materials is also highlighted.

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