Comparative Characterization of Octyl Bonded Phases using Methylene Selectivity Data

Bhagwat, V.V.; Bereznitski, Y.; Buszewski, Bogusław; Jaroniec, Mietek

doi:10.1080/10826079808005859

Cited by 16 publications

(20 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The concentration of the organic modifier must be higher near the stationary phase surface than in the bulk mobile phase. 15,16,[31][32][33] The structure-making effects due to the hydrophobic repulsion of the polar solvent molecules from the stationary phase surface and due to the hydrophobic attraction of the organic modifier molecules to the C18-silica gel surface are a cause of the restriction in their mobility. The intercept at Qst = 0 kJ mol -1 in Fig.…”

Section: Mechanism Of Surface Diffusionmentioning

confidence: 99%

Peak Parking-Moment Analysis Method for the Measurement of Surface Diffusion Coefficients

2009

View full text Add to dashboard Cite

The peak parking (PP)-moment analysis (MA) method was applied to the measurement of surface diffusion coefficients (Ds) in reversed-phase liquid chromatography using a C18-silica gel and an aqueous solution of methanol (70 vol%). The values of Ds measured by the PP-MA method were in agreement with those obtained by the pulse response (PR)-MA method, which is one of powerful strategies for the quantitative study on the mass transfer kinetics in columns and stationary phases. It was demonstrated that the PP-MA method is an alternative for the experimental measurement of Ds. The mechanism of surface diffusion was considered on the basis of molecular diffusion by introducing a restriction energy (Er) for surface diffusion. Physical meanings of Er were discussed by analyzing the correlation between the enthalpy change due to sample retention (Qst) and Ds. It seems that surface diffusion of a sample molecule is restricted by its retention strength and by the solvent structure formation due to the hydrophobic solvation of the stationary phase surface.

show abstract

Section: Mechanism Of Surface Diffusionmentioning

confidence: 99%

Peak Parking-Moment Analysis Method for the Measurement of Surface Diffusion Coefficients

2009

View full text Add to dashboard Cite

show abstract

“…For instance, if a 55:45 or 65:35 (v/v) methanol:water mobile phase was employed, the slopes of such plots on the [3,22]-ionene column were 0.17 or 0.12, respectively. This compares to an estimated slope of 0.57 for a 60:40 (v/v) methanol:water mobile phase on the ODS phase 60 or 0.37 on a Silasorb C-8 phase with a 60:40 (v/v) acetonitrile:water mobile phase, 63 which were the largest such values found in a cursory literature search. Included in Figure 2B are values for a variety of other C-18 phases (Hypersil C-18, Supelcosil C-18 LC PAH, Waters Resolve C-18, LiChrospher Si-C-18, and ASTEC C-18), 59,64,65,69 as well as some other stationary phase materials, such as porous glassy carbon (PGC) or PGC or zirconia (LTGC-Zr), that had been coated with low-temperature glassy carbon (LT-GC), 66 restricted-access polymeric polyglycerol monomethacrylateco-ethylene dimethacrylate (PGMADM), 67 a mixed phase containing aminopropyl and two alkyl (pentyl) amide moieties (SG-AP 2 ), 62 and Unisphere Al-C-18.…”

Section: General Characterization Of the Ionene-bonded Phasesmentioning

confidence: 69%

Covalently Bound Ionene Polyelectrolyte-Silica Gel Stationary Phases for HPLC

et al. 2001

View full text Add to dashboard Cite

Micelle-mimetic ionene-based stationary phases for high-performance liquid chromatography (HPLC) are prepared by attaching [3,16]- and [3,22]-ionenes to aminopropyl silica through a carbon-nitrogen bond. These [x,y]-ionenes are polyelectrolytic molecules consisting of dimethylammonium charge centers interconnected by alternating alkyl chain segments containing x and y methylene groups, some of which can form aggregate species whose properties mimic those of conventional surfactant micelles. These ionene-bonded stationary phases were characterized using different recommended HPLC test mixtures. Test solute chromatographic behavior on the ionene phases was found to be similar to that of intermediate oligomeric or polymeric C-18 and/or phenyl phases, depending upon the specific test mixture employed. In addition, the phases exhibit significant solute shape recognition ability. The ionene stationary phases were successfully employed for the separation of the components of the recommended ASTM reversed-phase test mixture, as well as for ortho-, meta- and para-disubstituted benzenes and other positional or geometric isomeric compounds. The ionene materials allow for chromatographic separations under either reversed-phase or ion-exchange conditions. The retention mechanism on these multimodal phases can occur by hydrophobic partitioning or electrostatic interactions, depending upon the characteristics of the components of the analyte mixture (neutral or anionic). The effects of alteration of the percent organic modifier, flow rate and temperature of the mobile phase on chromatographic retention and efficiency on these phases were briefly examined.

show abstract

“…As previously reported by Smith [28] and Figge et al [29] the CH2-selectivity under defined conditions is rather similar for typical RP-columns. Since CH2-selectivity is based on the penetration of the alkyl chain of test compounds in between the stationary phase ligands [30][31][32][33][34], it appears that columns I and IV are similar in that respect. The same holds true for columns II and III, where the parallel lines also suggest a similar CH2-selectivity for both these columns.…”

Section: Hydrophobicity Determinationmentioning

confidence: 94%

Comparative study of surface topography of high performance liquid chromatography columns in terms of hydrophobicity

et al. 2000

Self Cite

View full text Add to dashboard Cite

SummaryFour columns for RP HPLC have been compared. Three of them contained in their hydrophobic chains polar interaction sites: SG-AP phase (prepared in our laboratory), Supelcosil ABZ + Plus and Waters SymmetryShieldTM-RP8. The fourth was conventional column containing C18 ligands, Symmetry TM Cls. Becaus of its typical hydrophobic surface Symmetry TM C18 packing has been applied as a referential column in these investigations. All these stationary phase materials were examined in order to elucidate their retention behavior as well as their suitability for routine and specific chromatographic applications. Correlations between retention factors and n-octanol-water partition coefficients as well as quantitative relationships between descriptors of the structure of solutes and their chromatographic indices were studied. Awide range of parameters which are believed to influence the hydrophobicity of chemically bonded phases, such as carbon load, coverage density, methylene selectivity and results of QSRR calculations, have been considered. Based on these experiments the following conclusion regarding the hydrophobicity of the tested columns can be drawn: two general factors determine the arrangement of columns hydrophobicity, i. e., the nature of the structure of the stationary phase materials (i.e. mono-or polymeric or endcapped) and the length of the bonded ligands together with their density of coverage.

show abstract

Comparative Characterization of Octyl Bonded Phases using Methylene Selectivity Data

Cited by 16 publications

References 20 publications

Peak Parking-Moment Analysis Method for the Measurement of Surface Diffusion Coefficients

Peak Parking-Moment Analysis Method for the Measurement of Surface Diffusion Coefficients

Covalently Bound Ionene Polyelectrolyte-Silica Gel Stationary Phases for HPLC

Comparative study of surface topography of high performance liquid chromatography columns in terms of hydrophobicity

Contact Info

Product

Resources

About