Application Notes: Chiral
Two Novel Polysaccharide-Based Chiral Stationary Phases: CHIRALPAKˆ® AY-H and CHIRALCELˆ® OZ-H
June 1st 2009Polysaccharide-based chiral stationary phases (CSP) are successfully employed to achieve the majority of analytical and preparative enantioselective separations. However, there are a number of separations where significant modification or enhancement of selectivity is necessary. Two new columns, CHIRALPAK AY-H and CHIRALCEL OZ-H, have been introduced to meet these needs.
Reversed-Phase Enantioselective Chromatography with New µ-mm Chiral Stationary Phases
February 1st 2009To meet the growing need for fast reversed-phase enantiomer separations, two new 3-μm reversed-phase columns, CHIRALCEL® OD® -3R and CHIRALPAK® AD® -3R, have been introduced. High column performance and column stability under a wide range of conditions, including aqueous solvent systems suited to LC–MS, have been
Memory Effects of Mobile Phase Additives on the Whelk-O®1 Chiral Phase
February 1st 2009The Pirkle - Type Whelk-O®1 CSP is a synthetically made chiral selector covalently bonded to a silica support. This phase is well known in the industry for its broad degree of generality, mobile phase compatibility, and ability to invert elution order. Most commonly used polysaccharide coated CSP's are sensitive to the presence of certain mobile phase modifiers such as DEA, TEA, and TFA. Retained memory effects can adversely affect a separation resulting in broad and tailing peaks, no peak elution, and reduced or loss of separation altogether. To remove these unwanted memory effects, the column must be rinsed with an alcohol, such as methanol or ethanol. This is a time consuming and costly process. The Whelk-O®1 CSP does not exhibit any such retained memory behavior.
Chiral HPLC Separation of Enatiomers of Racemic Drugs Used in the Pharmaceutical Industry
September 1st 2008A large percentage of commercial and investigational pharmaceutical compounds are enantiomers and many of them show significant enantioselective differences in their pharmacokinetics and pharmacodynamics. The importance of chirality of drugs has been increasingly recognized, and the consequences of using them as racemates or as enantiomers have been frequently discussed in the pharmaceutical literature during recent years. With increasing evidence of problems related to stereoselectivity in drug action, enantioselective analysis by chromatographic methods has become the focus of intensive research of separation scientists. Most of the pharmaceutical and pharmacological studies of stereoselectivity of chiral drugs before the mid eighties involved pre-column derivatization of the enantiomers with chiral reagents forming diastereomers.
Fast Enantioselective Chromatography with 3-µm Particles
June 1st 2008The continuing and growing trend toward high-speed analysis in all fields of chromatography is also reflected in enantiomer separations. A variety of new 3-μm columns has been designed to meet this need. Applications of CHIRALCEL® OD-3 and CHIRALPAK® AD-3 in some enantiomer separations demonstrate the benefits of transitioning to such media.