Characterization of the acidity of residual silanol groups in microparticulate and monolithic reversed-phase columns

Herrero‐Martínez, José Manuel; Méndez, Alberto; Bosch, Elisabeth; Rosés, Martı́

doi:10.1016/j.chroma.2004.04.015

Cited by 31 publications

(9 citation statements)

References 36 publications

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“…However, silica surfaces can never be entirely bonded with ligands. Due to steric impedance, it is estimated that below half of the silanol groups present on silica surfaces are bonded with octadecylsilane molecules [ 1 ], and part of these silanols becomes permanently inaccessible to end-capping agents such as TMS during synthesis [ 34 , 35 ]. This incomplete substitution of silanols causes multiple interactions between the stationary phase (coating) and analytes to affect the extraction efficacy.…”

Section: Resultsmentioning

confidence: 99%

Benefits of Innovative and Fully Water-Compatible Stationary Phases of Thin-Film Microextraction (TFME) Blades

2021

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Octadecyl (C18) groups are arguably the most popular ligands used for preparation of solid phase microextraction (SPME) devices. However, conventional C18-bonded silica particles are not fully compatible with the nearly 100% aqueous composition of typical biological samples (e.g., plasma, saliva, or urine). This study presents the first evaluation of thin-film SPME devices coated with special water-compatible C18-bonded particles. Device performance was assessed by extracting a mixture of 30 model compounds that exhibited various chemical structures and properties, such as hydrophobicity. Additionally, nine unique compositions of desorption solvents were tested. Thin-film SPME devices coated with C18-bonded silica particles with polar end-capping groups (10 µm) were compared with conventional trimethylsilane end-capped C18-bonded silica particles of various sizes (5, 10, and 45 µm) and characteristics. Polar end-capped particles provided the best extraction efficacy and were characterized by the strongest correlations between the efficacy of the extraction process and the hydrophobicity of the analytes. The results suggest that the original features of octadecyl ligands are best preserved in aqueous conditions by polar end-capped particles, unlike with conventional trimethylsilane end-capped particles that are currently used to prepare SPME devices. The benefits associated with this improved type of coating encourage further implementation of microextractraction as greener alternative to the traditional sample preparation methods.

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Section: Resultsmentioning

confidence: 99%

Benefits of Innovative and Fully Water-Compatible Stationary Phases of Thin-Film Microextraction (TFME) Blades

2021

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“…Although a C 18 stationary phase is relatively inert, several studies on a variety of C 18 HPLC columns have indicated the presence of positively or negatively charged sites that can affect the retention of charged analytes . The effect of negatively charged sites on the stationary phase is eliminated by changing the pH of the mobile phase to below the p K a value of these sites . However, this also affects the degree of ionization of some of the anionic surfactants.…”

Section: Resultsmentioning

confidence: 99%

Fragment‐based approach to calculate hydrophobicity of anionic and nonionic surfactants derived from chromatographic retention on a C₁₈ stationary phase

Hammer

Haftka

Scherpenisse

et al. 2016

Enviro Toxic and Chemistry

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To predict the fate and potential effects of organic contaminants, information about their hydrophobicity is required. However, common parameters to describe the hydrophobicity of organic compounds (e.g., octanol-water partition constant [K ]) proved to be inadequate for ionic and nonionic surfactants because of their surface-active properties. As an alternative approach to determine their hydrophobicity, the aim of the present study was therefore to measure the retention of a wide range of surfactants on a C stationary phase. Capacity factors in pure water (k' ) increased linearly with increasing number of carbon atoms in the surfactant structure. Fragment contribution values were determined for each structural unit with multilinear regression, and the results were consistent with the expected influence of these fragments on the hydrophobicity of surfactants. Capacity factors of reference compounds and log K values from the literature were used to estimate log K values for surfactants (log KOWHPLC). These log KOWHPLC values were also compared to log K values calculated with 4 computational programs: KOWWIN, Marvin calculator, SPARC, and COSMOThermX. In conclusion, capacity factors from a C stationary phase are found to better reflect hydrophobicity of surfactants than their K values. Environ Toxicol Chem 2017;36:329-336. © 2016 The Authors. Environmental Toxicology and Chemistry Published by Wiley Periodicals, Inc. on behalf of SETAC.

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“…This observation seems reasonable in that conventional bare silica columns show greater cationic retention at higher pH than amide columns [18]. Cationic retention may be further suppressed on columns based on hybrid silica, as is the case for the Waters amide column [19,24], which may explain the greater ease of the dominance of anionic retention sites at low pH. Table 2 shows retention data on a hybrid bare silica column which shows exclusion of the bases nortriptyline and diphenhydramine with strong retention of the acidic probes.…”

Section: Interpretation Of Retention Results At Low Phmentioning

confidence: 81%

Study of retention and peak shape in hydrophilic interaction chromatography over a wide pH range

McCalley

2015

Journal of Chromatography A

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Characterization of the acidity of residual silanol groups in microparticulate and monolithic reversed-phase columns

Cited by 31 publications

References 36 publications

Benefits of Innovative and Fully Water-Compatible Stationary Phases of Thin-Film Microextraction (TFME) Blades

Benefits of Innovative and Fully Water-Compatible Stationary Phases of Thin-Film Microextraction (TFME) Blades

Fragment‐based approach to calculate hydrophobicity of anionic and nonionic surfactants derived from chromatographic retention on a C₁₈ stationary phase

Study of retention and peak shape in hydrophilic interaction chromatography over a wide pH range

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Characterization of the acidity of residual silanol groups in microparticulate and monolithic reversed-phase columns

Cited by 31 publications

References 36 publications

Benefits of Innovative and Fully Water-Compatible Stationary Phases of Thin-Film Microextraction (TFME) Blades

Benefits of Innovative and Fully Water-Compatible Stationary Phases of Thin-Film Microextraction (TFME) Blades

Fragment‐based approach to calculate hydrophobicity of anionic and nonionic surfactants derived from chromatographic retention on a C18 stationary phase

Study of retention and peak shape in hydrophilic interaction chromatography over a wide pH range

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Product

Resources

About

Fragment‐based approach to calculate hydrophobicity of anionic and nonionic surfactants derived from chromatographic retention on a C₁₈ stationary phase