Retention models and interaction mechanisms of benzene and other aromatic molecules with an amylose-based sorbent.
J Chromatogr A
; 1494: 55-64, 2017 Apr 21.
Article
em En
| MEDLINE
| ID: mdl-28320536
Stoichiometric displacement models have been widely used for understanding the adsorption mechanisms of solutes in chromatography systems. Such models are used for interpreting plots of solute retention factor versus concentrations of polar modifier in an inert solvent. However, these models often assume that dispersion forces are negligible and they are unable to account for solutes with significant aromatic interactions. In this study, a systematic investigation of the relationship between retention behavior and aromatic groups was performed using five simple aromatic molecules-benzene, naphthalene, mesitylene, durene, and toluene-with a commercially available amylose tris(3,5-dimethylphenylcarbamate)-based sorbent. The enthalpy changes of adsorption, determined from van't Hoff plots, were obtained separately in pure n-hexane and in pure isopropanol (IPA). In pure n-hexane, the solute adsorptions were driven by electrostatic interactions, favoring a T-shaped binding configuration (edge-to-face π-π interaction). The order of enthalpy change indicated the amount of effective T-shaped π-interactions. In pure IPA, solute adsorption was dominated by dispersion forces, favoring a sandwich binding configuration (face-to-face π-π interaction). The adsorption isotherms of toluene revealed that in pure IPA and in pure n-hexane, the isotherms were linear. The results suggested that the high solvent strength of IPA weakened the interactions between aromatic molecules. The retention behavior of the benzene, naphthalene, mesitylene, and durene as a function of IPA concentration was investigated. U-shaped retention curves were found for all aromatic solutes. A new retention model for monovalent aromatic solutes was developed for describing the U-shaped curves. Three key dimensionless groups were revealed to control the retention behavior. The models suggested that solvophobic interactions should be accounted for in the retention models used to investigate the retention behaviors of solutes associated with aromatic groups.
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Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Benzeno
/
Amilose
/
Modelos Teóricos
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
J Chromatogr A
Ano de publicação:
2017
Tipo de documento:
Article