The many faces of packed column supercritical fluid chromatography--a critical review.

Supercritical Fluid Chromatography and Extraction

Separation of polar solutes by packed column supercritical fluid chromatography

Determination of volatile aliphatic amines in air by solid-phase microextraction coupled with gas chromatography with flame ionization detection.

In this second part of the review heterogeneity of the silica surface is described and evidence is presented for the existence of a low population of strong adsorption sites. Methods of detection and determination of these strongly interacting sites are discussed. The last part of the review is devoted to the suppression of unwanted adsorption activity. Methods of blockage and special methods for the preparation of HPLC packings are described.

Silica surface controversies, strong adsorption sites, their blockage and removal. Part II

A new cross-linked cyanopropyl bonded phase silica (Delta-bond) has been studied as a stationary phase for packed column supercritical fluid chromatography of basic nitrogen-containing compounds. The bonded phase impedes access to uncapped silanol sites, thereby giving rise to better peak shapes and more rapid elution without the necessity of a polar modifier in the mobile phase. Experiments both at elevated temperature and in the presence of a methanol modifier revealed that there is no short- or long-term deleterious effect on the column as opposed to the conventional cyanopropyl phase.

Packed column supercritical fluid chromatography using deactivated stationary phases

Conventional and polymer-coated methyl, octyl and phenyl silica bonded phases have been compared employing analytes having a range of polarities. The effect of thermal treatment has also been examined. The polymer-coated silica phases gave sharper peaks and higher column efficiencies in all cases.

R. A. Henry

Papers

Packed column supercritical fluid chromatography using deactivated stationary phases

Packed column supercritical fluid chromatographic comparison of conventional and polymer-coated silica bonded phases