Simultaneous Determination of Total and Free Metal Ion Concentration in Solution by Sorption on Iminodiacetate Resin

1995 ◽  
Vol 67 (19) ◽  
pp. 3558-3563 ◽  
Author(s):  
Maria. Pesavento ◽  
Raffaela. Biesuz
Keyword(s):  
Simultaneous Determination ◽  
Metal Ion ◽  
Ion Concentration ◽  
Free Metal ◽  
Free Metal Ion

Ion Exchange Complexing Resins as Sensors for the Determination of Free Metal Ion Concentration at a Low Level

2008 ◽  
Vol 26 (3) ◽  
pp. 301-320 ◽  
Author(s):  
Maria Pesavento ◽  
Antonella Profumo ◽  
Raffaela Biesuz ◽  
Giancarla Alberti
Keyword(s):  
Ion Exchange ◽  
Metal Ion ◽  
Ion Concentration ◽  
Low Level ◽  
Free Metal ◽  
Free Metal Ion

scholarly journals Determination of the free-ion concentration of rare earth elements by an ion-exchange technique: implementation, evaluation and limits

2016 ◽  
Vol 13 (3) ◽  
pp. 478 ◽  
Author(s):  
Sébastien Leguay ◽  
Peter G. C. Campbell ◽  
Claude Fortin
Keyword(s):  
Ion Exchange ◽  
Natural Organic Matter ◽  
Metal Ion ◽  
Exchange Resin ◽  
Ion Exchange Resin ◽  
Ion Concentration ◽  
Free Ion ◽  
Free Metal ◽  
Free Metal Ion ◽  
Exchange Technique

Environmental context The lanthanides are a group of heavy elements (from lanthanum to lutetium) increasingly used in many electronic consumer products and little is known about their environmental mobility and toxicity. In natural systems, these elements will bind to natural organic matter but metal toxicity is usually defined by the free metal ion concentration. Here, we propose a method based on sample equilibration with an ion-exchange resin to measure the free lanthanide ion concentration in the presence of natural organic matter. Abstract An ion-exchange technique that employs a polystyrene sulphonate ion-exchange resin was developed for determining environmentally relevant free-ion concentrations of Ce, Eu, La and Nd. Owing to the high affinity of rare earth elements (REE) for the selected resin, this method requires the addition of an inert salt to increase the concentration of the counter-ions (i.e. cations that are exchanged with REE bound to the resin). The use of a batch equilibration approach to calibrate the resin allowed the implementation of the ion-exchange technique at reasonably low ionic strength (I = 0.1M). Several ligands were used to test the selectivity of the method, which proved to be highly selective for the free metal ion in presence of the tested cationic and anionic complexes (REE–nitrate, REE–malic acid and REE–nitrilotriacetic acid systems) and operational for very low proportions of REE3+, owing to the strong REE–resin interactions. The ion-exchange technique was also implemented to determine [Eu]inorg in the presence of natural humic matter (Suwannee River Humic Acid) and the results were compared with those obtained using equilibrium dialysis and those calculated with chemical equilibrium models. At pH 4.00, the measured [Eu]inorg values were in fairly good agreement with those predicted with the Windermere Humic Aqueous Model and Stockholm Humic Model, whereas the Non-Ideal Competitive Absorption model appeared to underestimate the [Eu]inorg. However, the inorganic europium concentrations were strongly underestimated (4 < [Eu]inorg, IET/[Eu]inorg, calc < 18) with the three prediction models at higher pH (5.3 and 6.2).

A study of the Ca2+ – Arsenazo III system and its application to the spectrophotometric determination of free calcium in solution

1990 ◽  
Vol 68 (11) ◽  
pp. 1932-1936 ◽  
Author(s):  
Byron Kratochvil ◽  
Xi-Wen He
Keyword(s):  
Ionic Strength ◽  
Calcium Ion ◽  
Calcium Binding ◽  
Metal Ion ◽  
Arsenazo Iii ◽  
Free Calcium ◽  
Ionic Calcium ◽  
Free Metal ◽  
Free Metal Ion

A two-wavelength method was applied to the determination of free, ionic calcium with Arsenazo III in solutions containing calcium-binding ligands. By this procedure impurities in the indicator can be corrected for, thereby allowing the use of commercial indicator preparations with purities as low as 80%. Only a 1:1 complex with a conditional log stability constant of 4.28 ± 0.13 at pH 4.6 and ionic strength 0.1 was found under the conditions studied. Key words: free metal ion determination, calcium ion speciation, spectrophotometry, arsenazo III, ion increment method for speciation.

scholarly journals AGNES: a new electroanalytical technique for measuring free metal ion concentration

2004 ◽  
Vol 566 (1) ◽  
pp. 95-109 ◽  
Author(s):  
J. Galceran ◽  
E. Companys ◽  
J. Puy ◽  
J. Cecilia ◽  
J.L. Garces
Keyword(s):  
Metal Ion ◽  
Ion Concentration ◽  
Free Metal ◽  
Free Metal Ion

scholarly journals Determination of free metal ion concentrations with AGNES in low ionic strength media

2013 ◽  
Vol 689 ◽  
pp. 276-283 ◽  
Author(s):  
D. Aguilar ◽  
C. Parat ◽  
J. Galceran ◽  
E. Companys ◽  
J. Puy ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Metal Ion ◽  
Ion Concentrations ◽  
Low Ionic Strength ◽  
Free Metal ◽  
Free Metal Ion

Spectrophotometric determination of free, ionized, metal ion concentrations in solution by an indicator increment method. Application to the determination of free Mg2+ with calmagite

1995 ◽  
Vol 73 (2) ◽  
pp. 296-302
Author(s):  
Hongji Ren ◽  
Byron Kratochvil ◽  
Xiwen He
Keyword(s):  
Metal Ion ◽  
Ion Concentration ◽  
Multiple Equilibrium ◽  
Conditional Stability ◽  
Ligand Complex ◽  
Conditional Stability Constant ◽  
Visible Spectra ◽  
Free Magnesium ◽  
Free Metal

A spectrophotometric method, called the Indicator Increment Method, is described in which varying amounts of a complexing indicator are added to a sample and the visible spectra recorded after each addition. Through multiple equilibrium calculations the free metal ion concentration, as well as total metal and total ligand concentrations, can be estimated in systems that contain a single metal ion and one ligand. The technique was tested successfully for the determination of free magnesium in the presence of NTA, phosphate, or oxalate using calmagite as indicator. The method requires the approximate conditional stability constant of the metal–ligand complex to be known beforehand. Keywords: ionized magnesium, indicator increment method, spectrophotometry.

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