Comparison of chiral separations of aminophosphonic acids and their aminocarboxylic acid analogs using a crown ether column.

Crown ethers are capable of complexing with primary amines and have been utilized in chromatography to separate amino acid racemates. This application has been extended to resolve (1-amino-1-phenylmethyl)phosphonic acid and (1-aminoethyl)phosphonic acid racemates, along with their aminocarboxylic acid analogs (2-phenylglycine and alanine, respectively), via a ChiroSil RCA crown ether based chiral stationary phase. Effects of the organic modifier, temperature, and acid type and concentration on retention and selectivity were also investigated.

Development of supercritical fluid extraction and supercritical fluid chromatography purification methods using rapid solubility screening with multiple solubility chambers.

Rapid solubility screening in diverse supercritical fluids (SCFs) was carried out via multiple solubility chambers with a trapping device and online ultraviolet (UV) detection. With this device, it was possible to rapidly study the solubility variations of multiple components in a mixture. Results from solubility studies have been used to develop efficient supercritical fluid extraction (SFE) and supercritical fluid chromatography (SFC) methods.

Supercritical fluid chromatography comparison of the poly(trans-1,2-cyclohexanediyl-bis acrylamide) (P-CAP) column with several derivatized polysaccharide-based stationary phases.

The poly(trans-1,2-cyclohexanediyl-bis acrylamide) (P-CAP) column has so far been primarily used with normal phase and polar organic mobile phase chromatography. Its use in supercritical fluid chromatography (SFC) was investigated via the analysis of 40 commercial and 100 proprietary compounds using a 12-min gradient with methanol as a modifier. Results were then compared against those obtained from the popular derivatized polysaccharide-based chiral stationary phases (CSPs) such as Chiralpak AD-H and Chiralpak AS-H as well as Chiralcel OD-H and Chiralcel OJ-H columns.

Purification method development for chiral separation in supercritical fluid chromatography with the solubilities in supercritical fluid chromatographic mobile phases.

A comprehensive approach was applied to develop a chiral purification method for an analyte that was found to be unusually difficult to scale-up in supercritical fluid chromatography (SFC). This was performed by studying major factors such as the solubility of an analyte in SFC mobile phases, impurity profiles, and cycle time. For this case study, the solubility in SFC mobile phase was measured by a packed column technique, coupled with a novel trapping mechanism to enhance measurement precision in SFC conditions.

Supercritical fluid chromatography tandem-column method development in pharmaceutical sciences for a mixture of four stereoisomers.

A tandem-column method using Chiralpak AD-H and Chiralcel OD-H columns was achieved for baseline separation of a mixture of chiral pharmaceutical compounds (i.e., four stereoisomers) via supercritical fluid chromatography (SFC) with a mobile phase consisting of 90% liquid carbon dioxide and 10% ethanol:isopropanol (50:50 v/v).

Enantioselective separation of racemic secondary amines on a chiral crown ether-based liquid chromatography stationary phase.

The first general enantioselective separation of racemic secondary amines on a crown ether-based liquid chromatography chiral stationary phase (CSP) is presented. The CSP is based on (+)- or (-)-(18-crown-6)-2,3,11,12-tetracarboxylic acid covalently bonded to silica gel. A mobile phase containing methanol, acetonitrile, triethylamine and acetic acid was employed in these separations of secondary amines with crown ether CSPs.