LCGC The Peak - July 2008 - (Page 10) 10 THE PEAK JULY 2008 Figure 1: Polarity of various stationary phases. based chiral columns: AD-H, AS-H, OD-H, and OJ-H (5). This application can be extended to other diverse structural motifs such as diastereoisomers (6) and cis-trans isomers (7). High-throughput screening and purification of achiral molecules with achiral packed columns also have been performed under SFC conditions (8–10); although the separations generally are carried out using more polar modified beds such as amino, cyano, and diol columns. Figure 1 illustrates the polarity of achiral columns used for the separation of achiral molecules. Increasing Polarity of Column Phases type, percentage of mobile phase co-solvent (methanol), flow rate, pressure, and temperature to achieve maximum resolution for a series of chemically diverse compounds that were not separable using reversed-phase HPLC conditions. Experimental The use of nonpolar achiral stationary phases under SFC conditions, however, is an area in which less attention has been devoted. The ability to separate drugs of the same family using C18 packed column SFC, including antipsychotics (11), antidepressants (12), and anticonvulsants (13) has been explored in the past. In this article, we have explored systematically the use of nonpolar stationary phases (C18, C8, and phenyl) under SFC conditions. We have optimized key variables such as column HPLC-grade methanol, acetonitrile, water, and formic acid, were all obtained from EMD (Gibbstown, New Jersey). Analytical SFC: Injections (5 L) were delivered to a Berger analytical SFC system (Newark, Delaware) consisting of a dualpump 1200 fluid control module, an ALS 3000 autosampler, a column oven (TCM 2100), and a model 1100 UV detector (Agilent Technologies, Wilmington, Delaware). A single wavelength at 230 nm was used for all samples. SFC-grade (99.9995% pure) carbon dioxide furnished by Linde Gas (Murray Hill, New Jersey) was delivered by dip-tube. Methanol was the co-solvent with no additives utilized. Constant conditions were an outlet pressure of 1500 psi, temperature of 30 °C, flow rate of 2 mL/min, wavelength at 230 nm, unless otherwise noted. Resolution (Rs), retention time (tR), and asymmetry values were calculated using Pronto software
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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