REVERSED-PHASE LIQUID-CHROMATOGRAPHIC MEASUREMENT OF THE INFLUENCE OFA CO-MODIFIER FUNCTIONAL-GROUP ON THE RETENTION BEHAVIOR OF THE BETA-CYCLODEXTRIN PYRENE COMPLEX
N. Husain et al., REVERSED-PHASE LIQUID-CHROMATOGRAPHIC MEASUREMENT OF THE INFLUENCE OFA CO-MODIFIER FUNCTIONAL-GROUP ON THE RETENTION BEHAVIOR OF THE BETA-CYCLODEXTRIN PYRENE COMPLEX, Journal of chromatography, 635(2), 1993, pp. 211-219
Reversed-phase liquid chromatography was used to determine the stoichi
ometry and formation constants of the complex of beta-cyclodextrin wit
h pyrene in the presence of several secondary modifiers in a 59% (v/v)
methanol in water mobile phase. All secondary modifiers contained a b
ulky and hydrophobic tert.-butyl moiety attached to functional groups
of varying polarity and heteroatom composition. Although pyrene exhibi
ts no interaction with beta-cyclodextrin in a 59% (v/v) methanol in wa
ter solvent alone, the addition of a co-modifier resulted in dramatica
lly short retention times. The stoichiometry of the beta-cyclodextrin-
pyrene was determined to be predominantly 2:1. Formation constants wer
e estimated to be approximately 10(4) M-2. Adding functionality and in
creasing chain length in co-modifiers resulted in a corresponding enha
ncement of formation constants and reduction of capacity factors. The
effects of pH on the equilibrium and the applications of co-modifier e
ffects in environmental analysis are discussed.