LCGC The Peak - July 2008 - (Page 8) 8 THE PEAK JULY 2008 Evaluation of Nonpolar Reversed-Phase Columns Under Supercritical Fluid Conditions Eric E. Pullen, Regis Technologies, Inc., and Keith R. Hornberger, William R. Hall, Manon S. Villeneuve, and Luke A. Miller, GlaxoSmithKline Supercritical fluid chromatography or subcritical fluid chromatography (SFC) is considered a normal-phase technique. In this article, we sought to examine whether it was feasible to use nonpolar columns (for example, C18) under SFC conditions to separate compounds that closely eluted or co-eluted by gradient and isocratic reversed-phase high performance liquid chromatography (HPLC). We evaluated temperature, pressure, percent co-solvent, flow rate, and their effects on resolution (Rs) when operating reversed-phase columns under SFC conditions. S upercritical fluid chromatography (SFC) is known as a powerful technique for the separation of racemic mixtures into their respective enantiomers. Stationed between gas chromatography (GC) and high performance liquid chromatography (HPLC) in terms of theoretical plates (1), SFC provides for a low-viscosity mobile phase, enabling high flow rates and therefore faster separations. Another feature is that resolution is greatly enhanced by way of sharper peaks due to the high diffusivity of the solutes in the mobile phase (2). The approach also has been advertised greatly because of environmental friendliness, purification of thermolabile compounds, and its three variable parameters — pressure, temperature, and co-solvent (3). Resolution of racemates by SFC is based upon the diastereomeric formation of the molecule and its interaction with the chiral stationary phase (4). Separations are achievable greater than 80% of the time using one or more of the following four polysaccharide-
Table of Contents Feed for the Digital Edition of LCGC The Peak - July 2008 LCGC The Peak - July 2008 Contents From the Editor Evaluation of Nonpolar Reversed-Phase Columns Under Supercritical Conditions Enhancing GC–MS Analysis of Trace Compounds Using a New Dynamic Approach to Reducing Background Interference Industry News Events Education LCGC The Peak - July 2008 LCGC The Peak - July 2008 - LCGC The Peak - July 2008 (Page Cover1) LCGC The Peak - July 2008 - LCGC The Peak - July 2008 (Page Cover2) LCGC The Peak - July 2008 - LCGC The Peak - July 2008 (Page 3) LCGC The Peak - July 2008 - Contents (Page 4) LCGC The Peak - July 2008 - Contents (Page 5) LCGC The Peak - July 2008 - Contents (Page 6) LCGC The Peak - July 2008 - From the Editor (Page 7) LCGC The Peak - July 2008 - Evaluation of Nonpolar Reversed-Phase Columns Under Supercritical Conditions (Page 8) LCGC The Peak - July 2008 - Evaluation of Nonpolar Reversed-Phase Columns Under Supercritical Conditions (Page 9) LCGC The Peak - July 2008 - Evaluation of Nonpolar Reversed-Phase Columns Under Supercritical Conditions (Page 10) LCGC The Peak - July 2008 - Evaluation of Nonpolar Reversed-Phase Columns Under Supercritical Conditions (Page 11) LCGC The Peak - July 2008 - Evaluation of Nonpolar Reversed-Phase Columns Under Supercritical Conditions (Page 12) LCGC The Peak - July 2008 - Evaluation of Nonpolar Reversed-Phase Columns Under Supercritical Conditions (Page 13) LCGC The Peak - July 2008 - Evaluation of Nonpolar Reversed-Phase Columns Under Supercritical Conditions (Page 14) LCGC The Peak - July 2008 - Evaluation of Nonpolar Reversed-Phase Columns Under Supercritical Conditions (Page 15) LCGC The Peak - July 2008 - Evaluation of Nonpolar Reversed-Phase Columns Under Supercritical Conditions (Page 16) LCGC The Peak - July 2008 - Evaluation of Nonpolar Reversed-Phase Columns Under Supercritical Conditions (Page 17) LCGC The Peak - July 2008 - Enhancing GC–MS Analysis of Trace Compounds Using a New Dynamic Approach to Reducing Background Interference (Page 18) LCGC The Peak - July 2008 - Enhancing GC–MS Analysis of Trace Compounds Using a New Dynamic Approach to Reducing Background Interference (Page 19) LCGC The Peak - July 2008 - Enhancing GC–MS Analysis of Trace Compounds Using a New Dynamic Approach to Reducing Background Interference (Page 20) LCGC The Peak - July 2008 - Enhancing GC–MS Analysis of Trace Compounds Using a New Dynamic Approach to Reducing Background Interference (Page 21) LCGC The Peak - July 2008 - Enhancing GC–MS Analysis of Trace Compounds Using a New Dynamic Approach to Reducing Background Interference (Page 22) LCGC The Peak - July 2008 - Enhancing GC–MS Analysis of Trace Compounds Using a New Dynamic Approach to Reducing Background Interference (Page 23) LCGC The Peak - July 2008 - Enhancing GC–MS Analysis of Trace Compounds Using a New Dynamic Approach to Reducing Background Interference (Page 24) LCGC The Peak - July 2008 - Enhancing GC–MS Analysis of Trace Compounds Using a New Dynamic Approach to Reducing Background Interference (Page 25) LCGC The Peak - July 2008 - Industry News (Page 26) LCGC The Peak - July 2008 - Events (Page 27) LCGC The Peak - July 2008 - Events (Page 28) LCGC The Peak - July 2008 - Events (Page 29) LCGC The Peak - July 2008 - Education (Page 30) LCGC The Peak - July 2008 - Education (Page 31) LCGC The Peak - July 2008 - Education (Page 32) LCGC The Peak - July 2008 - Education (Page Cover4)
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