LCGC The Peak - July 2008 - (Page 15) JULY 2008 THE PEAK 15 Figure 5: SFC Separation of G and H using (a) phenyl, (b) C8, and (c) C18 columns using 5% methanol in carbon dioxide, 2.0 mL/min flow rate, 1500 psi, at 30 °C. (d) A graphic summary of the resolution obtained between G and H as a function of % methanol for each column. phase HPLC gradient conditions, this mixture was closely eluted (Figure 6). The six-component mix was run by isocratic reversed-phase HPLC on the C18 column using both methanol–water and acetonitrile–water (0.1% formic acid in each) (Figures 7 and 8). Even these tailored methods could not baseline resolve the sample. The mixture was then subjected to a consensus “best conditions” SFC separation based upon the experiments separating compounds G-H and A, H, and I (C18 column, 5% methanol in the mobile phase). With this more challenging separation, we also explored other separation parameters, including pressure, temperature (Figure 9) and flow rate (Figure 10). As illustrated in Figure 9, none of the conditions surveyed offered baseline separation of all six compounds, although some conditions were close to achieving this goal. Lowering temperatures (Figures 9a and 9c and Figures 9b and 9d) caused shorter retention times and somewhat better resolutions. Changing pressure (Figures 9a and 9b and Figures 9c and 9d) caused minimal differences in overall resolution, particularly at 30 °C. Figure 9a showed the best resolution of the six compounds and was, therefore, chosen for optimization. With a slight reduction in flow rate from 2.0 mL/min to 1.3 mL/min, it was possible to achieve a baseline resolution of the six-component mix-
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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