Evaluation of column temperature as a means to alter selectivity in the cation exchange separation of alkali metals, alkaline earth metals and amines

Hatsis, Panos; Lucy, Charles A.

doi:10.1039/b106639k

Cited by 32 publications

(46 citation statements)

References 39 publications

(75 reference statements)

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“…For example, with comparable retention, compound 4 (an amino acid with partial positive charge, ΔH° = −3.61 kJ/mol) has a much bigger enthalpy change than compound 5 (a base with one positive charge, ΔH° = −0.84 kJ/mol). Similar differences in enthalpy changes were also observed in studies on the ion exchange of monovalent and divalent metal cations, where divalent cations show much weaker dependence of retention on temperature than monovalent cations [51][52][53][54].…”

supporting

confidence: 58%

Application of silica-based hyper-crosslinked sulfonate-modified reversed stationary phases for separating highly hydrophilic basic compounds

Luo

Paek

et al. 2008

Journal of Chromatography A

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The separation and determination of hydrophilic basic compounds are of great importance in many fields including clinical and biological research, pharmaceutical development and forensic analysis. However, the most widely used analytical separation technique in these disciplines, reversed-phase liquid chromatography (RPLC), usually does not provide sufficient retention for several of the important classes of highly hydrophilic basic compounds including catecholamines, many drug metabolites and many drugs of abuse. Commonly eluents having little or no organic modifier and/ or strong ion pairing agents must be used to achieve sufficient retention and separation. Use of highly aqueous eluents can lead to column failure by dewetting, resulting in poor retention, selectivity, reproducibility and slow recovery of performance. The use of a strong ion pairing agent to increase retention renders the separation incompatible with mass spectrometric detection and complicates preparative separations. This paper describes the successful applications of a novel type of silica-based, hyper-crosslinked, sulfonate-modified reversed stationary phase, denoted as − SO 3 -HC-C 8 -L, for the separation of highly hydrophilic cations and related compounds by a hydrophobically assisted cation-exchange mechanism. Compared to conventional reversed-phases, the − SO 3 -HC-C 8 -L phase showed significantly improved retention and separation selectivity. Concurrently, due to the presence of both cation-exchange and reversed-phase retention mechanisms and the high acid stability of hypercrosslinked phases, the separation can be optimized by changing the type or concentration of ionic additive or organic modifier, and by varying the column temperature. In addition, gradients generated by programming the concentration of either the ionic additive or the organic modifier can be applied to reduce the analysis time without compromising resolution. Furthermore, remarkably different chromatographic selectivities, especially toward cationic solutes, were observed upon comparison of the − SO 3 -HC-C 8 -L phase with conventional reversed-phases. We believe that the combination of these two types of stationary phases will be very useful in two-dimensional liquid chromatography.

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confidence: 58%

Application of silica-based hyper-crosslinked sulfonate-modified reversed stationary phases for separating highly hydrophilic basic compounds

Luo

Paek

et al. 2008

Journal of Chromatography A

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“…Shaw et al [16,17] studied the retention of lanthanides on the same column, but under suppressed electrostatic interactions and found changes to peak efficiency minimal in the temperature range between 25 and 408C. Intensive investigations of temperature effects for the range between 27 and 608C on the retention of alkalineearth metal cations on an IonPac CS12A column have also been performed by Hatsis and Lucy [30], who confirmed the decrease in retention times of these cations with increase in the column temperature and noted improvements in peak efficiencies of 14 -34% at 608C as compared with those at 278C. They also did not find any significant changes in peak asymmetry at different temperatures.…”

Section: The Main Factors Influencing Separation In Hpcic 221 Tempementioning

confidence: 99%

“…In the case of hydrophilic amino acid-type silica-based chelating ion-exchangers the addition of ACN, methanol, or 2-propanol did not produce any significant changes in separation selectivity but reduced the retention of alkaline-earth and transition metal cation by 10 -15% [41]. Hatsis and Lucy [30] investigated the effect of addition of ACN on the separation of alkaline-earth metal cations on Ionpac CS12 column and observed a decrease in retention times of these cations. They also noted a small decrease in peak efficiencies without changes in peak asymmetry.…”

Section: Organic Solvent Additivesmentioning

confidence: 99%

Recent developments in the high‐performance chelation ion chromatography of trace metals

Nesterenko¹,

Jones

2007

J of Separation Science

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Review Recent developments in the high-performance chelation ion chromatography of trace metalsThere have been a number of significant developments in the high-performance chelation ion chromatography (HPCIC) of trace metals in recent years. This review focuses on these developments, while giving important information on the fundamental parameters controlling the chelation sorption mechanism, including type of chelating group, stability constants, kinetics, and column temperature. The discussion pays particular attention to the types and properties of efficient chelating stationary phases which have been fabricated for certain groups of metals. The review also describes a number of major improvements in postcolumn reaction detection including the use of the latest reagents and noise reduction strategies to improve sensitivity and reduce LOD. In the final section, an indication of the applicability of HPCIC to a range of complex sample types is given with some key examples and chromatograms using the latest high-efficiency chelating phases.

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“…Therefore the distribution coefficient of an analyte ion decreases with an increase in temperature when the background eluent counterion in the mobile phase has stronger affinity than that of the analyte ion for the ion-exchanger, whereas it increases when eluted by a weaker counterion. [14][15][16][17][18] Presuming that the dependence of ion-exchange selectivity observed for simple inorganic ions on temperature can be attributed to the change in hydration of the ions in the solution phase and/or in the ion-exchange resin with temperature, we investigated the effect of temperature on the rst-shell coordination structures of Rb + , Sr 2+ , Br À and I À in aqueous solution and those for Rb + and Sr 2+ in a sulfonated styrenedivinylbenzene copolymer cation-exchange resin in the temperature range from ambient temperature to 450 K by X-ray absorption ne structure (XAFS) spectroscopy. 19 The spectral changes observed for these ions indicate that the number of coordinated rst shell water molecules decreases with an increase in temperature.…”

Section: Introductionmentioning

confidence: 99%

Synergistic effect of temperature and background counterions on ion-exchange equilibria

et al. 2018

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The effects of temperature and background counterions on ion-exchange selectivity for alkali metal ions and tetraalkylammonium ions on strongly acidic cation-exchange resins have been investigated using superheated water ion-exchange chromatography (SW-IEC). We have found out that alkali metal ions show reversal in the order of the distribution coefficient (K D ), from Li + < Na + < K + < Rb + in water at ordinary temperature to Rb + < K + < Na + < Li + in superheated water, when a relatively large cation such as cesium ion is used as the background counterion. The effect of counterion on the ion-exchange selectivity is enhanced with the ion-exchange resins of higher ion-exchange capacity and cross-linking degree. Tetraalkylammonium ions chosen as model ions for poorly hydrated ions also exhibit reversal in the order of K D at around 430 K in superheated water. However, the effect of the nature of alkali metal counterions on the change in K D values of tetraalkylammonium ions is rather small compared with the effect on the K D of alkali metal ions. These results are attributed to the change in local hydration structures of the ions in the ion-exchange resin due to dehydration of alkali metal ions enhanced by interionic contacts of the analyte ion with the coexisting counterion and lower hydration energy of the ions at elevated temperatures. Although it has been considered that temperature is not effective at changing the ion-exchange separation selectivity, significant selectivity changes can be achieved by SW-IEC.

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Evaluation of column temperature as a means to alter selectivity in the cation exchange separation of alkali metals, alkaline earth metals and amines

Cited by 32 publications

References 39 publications

Application of silica-based hyper-crosslinked sulfonate-modified reversed stationary phases for separating highly hydrophilic basic compounds

Application of silica-based hyper-crosslinked sulfonate-modified reversed stationary phases for separating highly hydrophilic basic compounds

Recent developments in the high‐performance chelation ion chromatography of trace metals

Synergistic effect of temperature and background counterions on ion-exchange equilibria

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