Adsorption isotherms and retention behavior of 1,1'-bis(2-naphthol) on CHIRIS AD1 and CHIRIS AD2 columns.
The separation of the atropoisomers of 1,1'-bis(2-naphthol) was studied on CHIRIS AD1 and CHIRIS AD2, two Pirkle-type chiral stationary phases. Satisfactory selectivity was found only on CHIRIS AD2. The ternary mobile phases comprised hexane, dichloromethane and methanol. The effects of their composition and of the temperature on the retention under analytical conditions and on the single-component and competitive isotherms were investigated. The retention of the R- and S-isomers on CHIRIS AD1 and CHIRIS AD2 is controlled by the enthalpic contribution to adsorption, but the effect of the mobile phase on the retention should be attributed mainly to the entropic contribution. The adsorption of the less retained R-isomer is controlled by the achiral interactions, which are the same as for the S-isomer. The single-component and competitive isotherms of the R- and S-isomers are adequately described by the sum of a Langmuir term for the achiral contribution to adsorption and a linear-term characterising the selective or chiral adsorption of the S-isomer in the concentration range experimentally available, i.e. within the solubility limit of 1,1'-bis(2-naphthol).
Department of Analytical Chemistry, University of Pardubice, Nám. Cs. legií 565, CZ 532, 10 Pardubice, Czech Republic.
Michal
M
Skavrada
Pavel
P
Jandera
Djamel E
DE
Cherrak
Ahmed
A
Aced
G
G
Guiochon
D000327:Adsorption; D009284:Naphthols / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013237:Stereoisomerism; D013816:Thermodynamics
D009284:Naphthols; C028405:2-naphthol