Chromatographie à contre courant et micelles inverses pour la séparation et l'extraction de cations métalliques

1996 ◽  
Vol 74 (2) ◽  
pp. 277-286 ◽  
Author(s):  
Alain Berthod ◽  
Jun Xiang ◽  
Serge Alex ◽  
Colette Gonnet-Collet
Keyword(s):  
Stationary Phase ◽  
Reverse Micelles ◽  
Countercurrent Chromatography ◽  
Metallic Ions ◽  
Ion Extraction ◽  
Extraction Constants ◽  
Lanthanide Cations ◽  
Diethylhexyl Phosphoric Acid ◽  
Aqueous Core ◽  
Theoretical Plates

Countercurrent chromatography (CCC) is a separation technique in which the stationary phase is a liquid. Diethylhexyl phosphoric acid (DEHPA) forms reverse micelles in heptane. Metallic ions, located in an aqueous phase, can be extracted into the aqueous core of the reverse micelles in the heptane phase. A CCC apparatus can be considered as a powerful mixing and extracting machine with efficiency above several hundreds of theoretical plates. La3+, Ce3+, Pr3+, and Nd3+ lanthanide cations were separated using CCC with a DEHPA-containing heptane stationary phase. Studying the retention variations with aqueous mobile phase pH, it was possible to determine the lanthanide extraction constants and separation coefficients. Overloading conditions are described. Frontal chromatography was performed using a Co2+ and Ni2+ solution. The Co2+ ions were concentrated in the heptane + DEHPA stationary phase, a part of the solution was deionized, and another part was enriched in only Ni2+ ions. This method also produced the extraction constants and separation coefficients. The use of CCC with a complexing stationary phase can be applied to any cation for ion filtering and concentration, or for deionization of aqueous phases. Key words: countercurrent chromatography, CCC; ion extraction, ion filtering, deionization, lanthanides, transition metals.

Separation of U and Pu by countercurrent chromatography with support-free liquid stationary phase in the TBP white spirit nitric acid system

2006 ◽  
Vol 48 (3) ◽  
pp. 284-287
Author(s):  
M. N. Litvina ◽  
D. A. Malikov ◽  
T. A. Maryutina ◽  
Yu. M. Kulyako ◽  
B. F. Myasoedov
Keyword(s):  
Nitric Acid ◽  
Stationary Phase ◽  
White Spirit ◽  
Countercurrent Chromatography ◽  
Acid System ◽  
Liquid Stationary Phase

Americium(III)/curium(III) separation by countercurrent chromatography using malonamide extractants

2005 ◽  
Vol 93 (1) ◽  
Author(s):  
B. F. Myasoedov ◽  
T. A. Maryutina ◽  
M. N. Litvina ◽  
D. A. Malikov ◽  
Yu. M. Kulyako ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Stationary Phase ◽  
Flow Rate ◽  
Mobile Phase ◽  
Countercurrent Chromatography ◽  
Column Length ◽  
Isocratic Elution ◽  
Phase Systems ◽  
Phase Retention

AbstractThe separation of Am(III) and Cm(III) by countercurrent chromatography (CCC) was achieved using the liquid phase systems "diamide–hydrogenated tetrapropylene (TPH)–HNOThe following diamide extractants have been studied: (i) N,N´-dimethyl-N,N´-dibutyltetradecylmalonamide (DMDBTDMA), (ii) N,N´-dimethyl-N,N´-dioctylhexyl-ethoxymalonamide (DMDOHEMA) and (iii) N,N´-dimethyl-N,N´-dibutyldodecylethoxymalonamide (DMDBDDEMA). It is shown that these diamides can be used for the separation of Am(III) and Cm(III) by CCC. Increasing the column length leads to an increase of the stationary phase retention on the column while improving the Am/Cm separation. Increasing the speed of rotation of the centrifuge from 660 to 950 rpm also results in increasing the stationary phase retention but does not influence the resolution of the Am/Cm separation. Decreasing the flow rate of the mobile phase from 1.0 to 0.5 mL/min leads to a better resolution of Am and Cm separation. The best Am/Cm separation was achieved with systems based on DMDBDDEMA and DMDOHEMA in TPH using a two-layer coil column and an isocratic elution mode. The application of CCC makes it possible to separate the elements within 100 min: the Cm fraction contains 99.5% of Cm(III) and 0.6% of Am(III) inventories and the Am fraction contains 99.4% of Am(III) and 0.5% of Cm(III).

A comparison of supports for quantitative gas chromatographic analysis of nickel and zinc dithiocarbamates

1984 ◽  
Vol 49 (1) ◽  
pp. 197-200
Author(s):  
Jana Chovancová ◽  
Ján Krupčík ◽  
Ján Garaj
Keyword(s):  
Stationary Phase ◽  
Chromatographic Analysis ◽  
Chromatographic Behaviour ◽  
Gas Chromatographic Analysis ◽  
Theoretical Plates

The gas chromatographic behaviour of nickel and zinc diethyldithiocarbamates was examined on various supports, mainly of the Chromaton and Chromosorb families, coated with polydimethylsiloxane nonpolar stationary phase. The coefficients of asymmetry, retention ratios and relative molar responses with respect to C28H58, and numbers of theoretical plates were determined. While poor results were obtained with Chromosorb G, Chromaton N Super appears to suit well to thedetermination.

scholarly journals Silica Monolithic Capillary Columns for Hilic Separations

2018 ◽  
Vol 46 (1) ◽  
pp. 39-42
Author(s):  
Dana Moravcová ◽  
Josef Planeta
Keyword(s):  
Stationary Phase ◽  
Separation Efficiency ◽  
Stationary Phases ◽  
Ammonium Hydroxide ◽  
Capillary Columns ◽  
Optimal Separation ◽  
Monolithic Capillary Columns ◽  
High Separation ◽  
Theoretical Plates ◽  
Separation Conditions

Abstract The monolithic capillary columns (0.1 mm x 150 mm) prepared by the acidic hydrolysis of tetramethoxysilane (TMOS) in the presence of polyethylene glycol (PEG) and urea were modified by zwitterionic stationary phases and evaluated under HILIC separation conditions by employing a mixture containing nucleosides and nucleotides. The polymeric layer of zwitterions did not affect the high separation efficiency of the original silica monolith. The prepared zwitterionic columns exhibited high separation efficiencies in a range 61,000-289,000 theoretical plates/m for a 2- methacryloyloxyethyl phosphorylcholine-based stationary phase and in a range 59,000-135,000 theoretical plates/m for a [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide-based stationary phase under optimal separation conditions. The grafted layer of zwitterions on the silica monolithic surface also significantly improved the separation selectivity to compounds of interest

Performance Comparison Between Monolithic, Core-Shell, and Totally Porous Particulate Columns for Application in Greener and Faster Chromatography

2018 ◽  
Vol 101 (6) ◽  
pp. 1985-1992 ◽  
Author(s):  
Adel Ehab Ibrahim ◽  
Hisham Hashem ◽  
Hanaa Saleh ◽  
Magda Elhenawee
Keyword(s):  
Stationary Phase ◽  
Mobile Phase ◽  
Separation Efficiency ◽  
Stationary Phases ◽  
Shape Selectivity ◽  
Performance Comparison ◽  
Core Shell ◽  
Porous Particles ◽  
Shell Particles ◽  
Theoretical Plates

Abstract Background: The introduction of monolithic rods and core-shell particles as new morphologies of packing materials different from the conventional totally porous particles resulted in a leap forward for performance in LC. Meanwhile, environmental safety has become increasingly important in many areas, especially in industry and research laboratories. Objective: This study compared the efficiencies of commercially available columns of different lengths and diameters when greener chromatographic conditions were utilized. The main purpose of this study is to help practitioners select the most appropriate stationary phase for faster and greener analysis. Methods: The three types of stationary phases were compared in terms of separation efficiency, number of theoretical plates, peak shape, selectivity, resolution, analysis time, mobile phase consideration, and permeability using six drug molecules. Results: Results indicated that core-shell and monolithic stationary phases had superiority over the conventional totally porous particles in terms of efficiency and speed of analysis. Monolithic rods had lower column backpressure and higher permeability, so they are more suitable for higher mobile phase flow rates and viscosities. However, core-shell particles provided enhanced peak shapes and number of theoretical plates. Conclusions: The choice will depend on the main purpose of analysis and the composition of the mobile phase. Compromise must be made to obtain the best trade-off between separation efficiency and analysis speed. Highlights: This study is the first to consider green chromatography concepts for the selection of the best stationary phase of new morphologies.

Synthesis and Characterization of Antiferromagnetic Kmnf3 Nanoparticles

1999 ◽  
Vol 577 ◽  
Author(s):  
C. Sangregorio ◽  
E. E. Carpenter ◽  
C. J. O'connor
Keyword(s):  
Magnetic Properties ◽  
Reverse Micelles ◽  
Exchange Coupling ◽  
Hysteresis Loops ◽  
Size Control ◽  
Synthesis And Characterization ◽  
Uniform Size ◽  
Average Size ◽  
Aqueous Core

ABSTRACTThe magnetic properties of nanosized antiferromagnetic particles of KMnF3 are presented. The particles were synthesized using the microemulsion technique, i.e. by using the aqueous core of reverse micelles as constrained microreactors for the precipitation of the particles. The structural characterization of the samples, accomplished by TEM and XRD, reveal that the samples consist of cubic-shaped, crystalline KMnF3 nanoparticles of uniform size. Control over the average size of the particles was achieved by changing the reaction time. Four different samples of average size in the range 13-35 nm were prepared. DC magnetic susceptibility measurements revealed superparamagnetic behavior of the particles. Hysteresis loops measured after field cooling the samples through TN were shifted. The shift is ascribed to the exchange coupling between the antiferromagnetic core of the particles and the uncompensated spin shell surrounding it.

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