On the Differences in the Mechanisms of Adsorption of Aromatic Heterocycles from Water–Acetonitrile Solutions on Octadecyl-Bonded Silica Gels

Autor:	B. R. Saifutdinov, Alexei K. Buryak
Rok vydání:	2019
Předmět:	010304 chemical physics Chemistry Silica gel Inorganic chemistry food and beverages Adsorbed molecule 02 engineering and technology Surfaces and Interfaces equipment and supplies 021001 nanoscience & nanotechnology Mole fraction 01 natural sciences chemistry.chemical_compound Colloid and Surface Chemistry Adsorption 0103 physical sciences Molecule lipids (amino acids peptides and proteins) Surface layer Physical and Theoretical Chemistry Linear correlation 0210 nano-technology Acetonitrile
Zdroj:	Colloid Journal. 81:555-562
ISSN:	1608-3067 1061-933X
DOI:	10.1134/s1061933x19050107
Popis:	Adsorption of some 1,3,4-oxadiazoles and 1,2,4,5-tetrazines from water–acetonitrile solutions on Luna C18 and Discovery C18 silica gels with grafted octadecyl groups has been studied in a wide range of compositions at temperatures of 313.15–333.15 K. The comparative analysis of the liquid-phase adsorption of the heterocycles has revealed a number of differences between the mechanisms of binding molecules of the studied compounds by the surfaces of these octadecyl-derivatives of silica gel. The log–log dependences of the retention factor on the molar fraction of acetonitrile in the solutions are strictly linear only for adsorption on Luna C18 silica gel, which is characterized by an increased hydrophobicity. For the adsorption of the studied heterocycles on Discovery C18 silica gel, the concentration dependences of the retention at low and high acetonitrile concentrations in the solution are described by quadratic functions and characterized by higher retention values as compared with those for the linear dependence because of the lower hydrophobicity of this silica gel. It has been found that the surface layer of Luna C18 modified silica gel is enriched with acetonitrile molecules to a higher extent than the surface layer of Discovery C18 silica gel. It has been shown that one adsorbed molecule of 1,3,4-oxadiazoles and 1,2,4,5-tetrazines displaces three and two molecules of pre-adsorbed acetonitrile from the surfaces of Luna C18 and Discovery C18 silica gels, respectively. Linear correlation equations have been proposed for calculating the retention of the studied heterocycles on Luna C18 and Discovery C18 silica gels from mobile phases of arbitrary compositions at different temperatures of chromatographic columns.
Databáze:	OpenAIRE
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