Critical contribution of nonlinear chromatography to the understanding of retention mechanism in reversed-phase liquid chromatography

Journal Article · Tue Nov 01 04:00:00 EST 2005 · Journal of Chromatography A

DOI:https://doi.org/10.1016/j.chroma.2005.02.007· OSTI ID:989576

Gritti, Fabrice ^[1]; Guiochon, Georges A ^[2]

---

1. University of Tennessee, Knoxville (UTK)
2. ORNL

The retention of most compounds in RPLC proceeds through a combination of several independent mechanisms. We review a series of recent studies made on the behavior of several commercial C{sub 18}-bonded stationary phases and of the complex, mixed retention mechanisms that were observed in RPLC. These studies are essentially based on the acquisition of adsorption isotherm data, on the modeling, and on the interpretation of these data. Because linear chromatography deals only with the initial slope of the global, overall, or apparent isotherm, it is unable fully to describe the complete adsorption mechanism. It cannot even afford clues as to the existence of several overlaid retention mechanisms. More specifically, it cannot account for the consequences of the surface heterogeneity of the packing material. The acquisition of equilibrium data in a wide concentration range is required for this purpose. Frontal analysis (FA) of selected probes gives data that can be modeled into equilibrium isotherms of these probes and that can also be used to calculate their adsorption or affinity energy distribution (AED). The combination of these data, the detailed study of the best constants of the isotherm model, the determination of the influence of experimental parameters (e.g., buffer pH and pI, temperature) on the isotherm constants provide important clues regarding the heterogeneity of the adsorbent surface and the main properties of the adsorption mechanisms. The comparison of similar data obtained for the adsorption of neutral and ionizable compounds, treated with the same approach, and the investigation of the influence on the thermodynamics of phase equilibrium of the experimental conditions (temperature, average pressure, mobile phase composition, nature of the organic modifier, and, for ionizable compounds, of the ionic strength, the nature, the concentration of the buffer, and its pH) brings further information. This review provides original conclusions regarding retention mechanisms in RPLC.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: SC USDOE - Office of Science (SC)
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 989576
• Journal Information: Journal of Chromatography A, Journal Name: Journal of Chromatography A Journal Issue: 2005 Vol. 1099; ISSN 0021-9673
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ADSORBENTS
ADSORPTION ISOTHERMS
ENERGY SPECTRA
EVALUATION
KINETICS
LIQUID COLUMN CHROMATOGRAPHY
RP-HPLC
THERMODYNAMICS
adsorption data reproducibility
adsorption energy distribution
adsorption isotherm
column heterogeneity
frontal analysis
ionizable compounds
organic modifier
pressure
retention mechanism
temperature