Dependence of the methylene selectivity on the composition of hydro-organic eluents for reversed-phase liquid chromatographic systems with alkyl bonded phases

Gilpin, R. K.; Jaroniec, Mietek; Lin, S.

doi:10.1007/bf02328504

Cited by 29 publications

(15 citation statements)

References 26 publications

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“…While literature on methylene selectivity at these particular conditions is not readily available, ln (α CH 2 ) in pure water has been reported on four C18 phases at slightly different tem- peratures near room temperature. 65 On the basis of these data, at an average temperature of 26.8 ± 2.0 °C, ln (α CH 2 ) is 1.39 ± 0.01. 65 Fortuitously, under our experimental conditions (ϕ = 0.05 and −7.5 °C), the solvent strength is similar to water at room temperature.…”

Section: Resultsmentioning

confidence: 92%

“…65 On the basis of these data, at an average temperature of 26.8 ± 2.0 °C, ln (α CH 2 ) is 1.39 ± 0.01. 65 Fortuitously, under our experimental conditions (ϕ = 0.05 and −7.5 °C), the solvent strength is similar to water at room temperature. This is because a decrease of 5 °C increases retention to about the same extent as a 1% increase in acetonitrile composition decreases retention.…”

Section: Resultsmentioning

confidence: 92%

“…The second method was to compare the methylene group selectivity, α CH 2 , from extrapolated k ′ values to a known value. While literature on methylene selectivity at these particular conditions is not readily available, ln (α CH 2 ) in pure water has been reported on four C18 phases at slightly different temperatures near room temperature . On the basis of these data, at an average temperature of 26.8 ± 2.0 °C, ln (α CH 2 ) is 1.39 ± 0.01 .…”

Section: Resultsmentioning

confidence: 97%

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Improving the Sensitivity, Resolution, and Peak Capacity of Gradient Elution in Capillary Liquid Chromatography with Large-Volume Injections by Using Temperature-Assisted On-Column Solute Focusing

2016

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Capillary HPLC (cLC) with gradient elution is the separation method of choice for the fields of proteomics and metabolomics. This is due to the complementary nature of cLC flow rates and electrospray or nanospray ionization mass spectrometry (ESI-MS). The small column diameters result in good mass sensitivity. Good concentration sensitivity is also possible by injection of relatively large volumes of solution and relying on solvent-based solute focusing. However, if the injection volume is too large or solutes are poorly retained during injection, volume overload occurs which leads to altered peak shapes, decreased sensitivity, and lower peak capacity. Solutes that elute early even with the use of a solvent gradient are especially vulnerable to this problem. In this paper, we describe a simple, automated instrumental method, temperature-assisted on-column solute focusing (TASF), that is capable of focusing large volume injections of small molecules and peptides under gradient conditions. By injecting a large sample volume while cooling a short segment of the column inlet at subambient temperatures, solutes are concentrated into narrow bands at the head of the column. Rapidly raising the temperature of this segment of the column leads to separations with less peak broadening in comparison to solvent focusing alone. For large volume injections of both mixtures of small molecules and a bovine serum albumin tryptic digest, TASF improved the peak shape and resolution in chromatograms. TASF showed the most dramatic improvements with shallow gradients, which is particularly useful for biological applications. Results demonstrate the ability of TASF with gradient elution to improve the sensitivity, resolution, and peak capacity of volume overloaded samples beyond gradient compression alone. Additionally, we have developed and validated a double extrapolation method for predicting retention factors at extremes of temperature and mobile phase composition. Using this method, the effects of TASF can be predicted, allowing determination of the usefulness of this technique for a particular application.

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 97%

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Improving the Sensitivity, Resolution, and Peak Capacity of Gradient Elution in Capillary Liquid Chromatography with Large-Volume Injections by Using Temperature-Assisted On-Column Solute Focusing

2016

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“…The mobile phase can influence selectivity in two ways. Solvent-strength selectivity (SSS) arises as a result of the use of the same organic modifier and changing its concentration in the mobile phase [33,34]. If different organic modifiers are used the contribution of a modifier to the different molecular interactions will influence the selectivity of seReview Chromatographia Supplement, Vol.…”

Section: Mobile Phase Selectivitymentioning

confidence: 99%

Possibilities and pitfalls in defining selectivity in HPLC

Szepesy

2000

Chromatographia

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Definition of selectivity Classification of solvent selectivity Rohrschneider-McReynolds system Solvent selectivity triangle Solubility parameter Linear solvation energy relationships Prediction of selectivity SummaryDefinition of chromatographic selectivity and the different selectivity terms, for example column selectivity, mobile phase selectivity, and temperature selectivity are discussed briefly. For classification of solvent selectivity the Rohrschneider-McReynolds system, the solvent selectivity triangle (SST) concept, the solubility parameter approach, and the linear solvation energy relationships (LSER) are compared. Shortcomings of the SST concept and application of the LSER method for the prediction of selectivity are discussed.

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“…Similarly, although the dependence of retention and selectivity on the chain length of alkyl bonded phases has been studied extensively (see refs 9-11 and the citations in ref 9), again the influence of intercalated solvents has been neglected. Recently, more quantitative treatments have been suggested (12)(13)(14) which consider both the competitive interactions that arise between the solute and solvents for a chemically modified solid as well as the solute-solvent and solvent-solvent interactions that occur in both the mobile and stationary phases (15)(16)(17)(18)(19)(20). In doing this an accurate description of the stationary phase's composition is needed since it may be significantly different than that of the eluent (12, 13, [21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Studies of the surface composition of phenyl and cyanopropyl bonded phases under reversed-phase liquid chromatographic conditions using alkanoate and perfluoroalkanoate esters

Gilpin¹,

Jaroniec²,

Lin³

1991

Anal. Chem.

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Two polar bonded phases, phenyl-silica and cyanopropylsllica, have been studied under reversed-phase conditions using homologues of alkanoate and perfluoroalkanoate esters as test solutes. For comparative purposes a similarly prepared n -butyl phase also has been studied under equivalent conditions. Retention measurements have been carried out as a function of mobile-phase composition for water-methanol and water-acetonitrile and Incremental methylene (-CH2-) and perfluoromethylene (~CF2~) selectlvltles calculated. These latter data have been used to estimate the thermodynamic constant K^, which describes the sorption equilibrium of solvents between mobile and stationary phases assuming Ideality of these phases. For water-methanol, differences In composition between the mobile and surface phases due to preferential Intercalation are small. However, the data Indicate a significant sorption excess of acetonitrile by the bonded phases. This preferential sorption of acetonitrile Is greatest for alkyl phases and decreases with increasing polarity of the bonded phase (l.e., cyano-silica < phenyl-silica < alkyl-silica).

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Dependence of the methylene selectivity on the composition of hydro-organic eluents for reversed-phase liquid chromatographic systems with alkyl bonded phases

Cited by 29 publications

References 26 publications

Improving the Sensitivity, Resolution, and Peak Capacity of Gradient Elution in Capillary Liquid Chromatography with Large-Volume Injections by Using Temperature-Assisted On-Column Solute Focusing

Improving the Sensitivity, Resolution, and Peak Capacity of Gradient Elution in Capillary Liquid Chromatography with Large-Volume Injections by Using Temperature-Assisted On-Column Solute Focusing

Possibilities and pitfalls in defining selectivity in HPLC

Studies of the surface composition of phenyl and cyanopropyl bonded phases under reversed-phase liquid chromatographic conditions using alkanoate and perfluoroalkanoate esters

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