Calibration of a detector for nonlinear responses

Enantioseparation of 1-phenyl-1-propanol on cellulose-derived chiral stationary phase by supercritical fluid chromatography

The separation of the enantiomers of 1-phenyl-1-propanol by supercritical fluid chromatography on a chiral stationary phase, which consists of cellulose tris (3,5-dimethylphenylcarbamate) coated on a silica support (Chiralcel-OD), is studied under overloaded, non-linear chromatographic conditions. Pulse experiments are performed at a temperature of 30 degrees C using supercritical CO(2) modified with methanol as a mobile phase. The parameters of the binary Langmuir adsorption isotherm are determined by the inverse method, comparing experimental and simulated peak responses. Isotherm parameters are derived for modifier concentrations between 1 and 5% (w/w) and operating pressures between 125 and 185 bar, and the dependency of the isotherm parameters, namely the Henry constant and the saturation capacity, on operating conditions is investigated.

Novel inverse liquid chromatography detector configuration for studying solid-liquid adsorption

Inverse liquid chromatography (ILC) is a physicochemical chromatographic technique for studying solid-liquid interactions and surface properties of unknown solid materials. However, such studies are dependent on the ability to self pack the sample powder into a LC column in a reliable and robust manner. In practise, this is often difficult and anomalous chromatograms can be encountered quite frequently. Results obtained with a novel LC system configuration utilising both pre and post-column UV-vis detectors for ILC studies are reported here which greatly assist in our attempts to interpret such chromatograms. The operational issues for using a two detector system are discussed including the use of both detectors in the linear concentration regime; with the choice of an optimal detector wavelength being the most critical factor. The two detector system was demonstrated to be capable of verifying reversible adsorption processes, as well as assisting in the interpretation of complex or problematic chromatograms. This paper demonstrates that the two detector ILC system can offer a number of practical benefits in the study of complex chromatographic phenomena.

Calibration of detector responses using the shape and size of band profiles

A new method consisting of using band profiles to calibrate the response of a detector, without making frontal analysis measurements, is discussed. A model for the calibration-curve expression is proposed. It is convenient and reasonably accurate even when the detector response deviates slightly from linear behavior at low concentrations.