INTERACTIONS OF BASIC COMPOUNDS IN REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY - INFLUENCE OF SORBENT CHARACTER, MOBILE-PHASE COMPOSITION, AND PH ON RETENTION OF BASIC COMPOUNDS
D. Sykora et al., INTERACTIONS OF BASIC COMPOUNDS IN REVERSED-PHASE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY - INFLUENCE OF SORBENT CHARACTER, MOBILE-PHASE COMPOSITION, AND PH ON RETENTION OF BASIC COMPOUNDS, Journal of chromatography, 758(1), 1997, pp. 37-51
Citations number
47
Categorie Soggetti
Chemistry Analytical","Biochemical Research Methods
Differences in a degree of base deactivation of selected reversed-phas
e sorbents were evaluated. Five silica-based sorbents (SGX C-18, LiChr
osorb RP-18, LiChrospher RP-select B, Purospher RP-18, Symmetry C-18),
a polybutadiene-coated alumina (Aluspher RP-select B) and 2-hydroxyet
hylmethacrylate-based stationary phase (HEMA-BIO 1000 C-18) were compa
red. The best results were obtained for Symmetry C-18 and HEMA-BIO 100
0 C-18. For testing purposes a set of nineteen basic compounds differi
ng in pK(a) constants and hydrophobicity was used. The bases possessin
g high pK(a) values (pK(a)>9.0) and/or low hydrophobicity proved to be
the best indicators of sorbent surface deactivation. Dependencies of
capacity factor on pH of the mobile phase were measured. Shape deviati
ons between the sigmoidal theoretically predicted and experimentally o
btained curves evidence for a complex retention mechanism in which not
only hydrophobic but also other interactions, for example, ion-exchan
ge, participate. The effect of methanol content in the mobile phase on
the dissociation of buffer and a basic analyte used was studied. The
characteristic shifts of k versus pH of the mobile phase dependencies
caused by the addition of methanol were found to be in a good agreemen
t with theory.