LCGC The Peak - April 2008 - (Page 8) 8 THE PEAK APRIL 2008 LC P Load L1 L2 Inject SEC W Figure 1: Typical valve-switching configuration for LC LC. Reprinted from reference 4 with permission. The common way to perform LC LC involves a first-dimension separation that is relatively slow, with a typical analysis time of 1 h or longer. Fractions of the effluent from this first-dimension column are collected in a loop of a switching valve. When this valve is switched, the fraction is injected onto a second column, which provides a much faster separation, typically with an analysis time of a minute or less. While one fraction is being analyzed on the second-dimension column, a new fraction is being collected in another loop connected to the same valve (or by using a second valve). One popular configuration employs a two-way 10-port switching valve, as illustrated in Figure 1. To construct an LC LC system requires (at least) two columns and two pumping systems. Detection typically takes place after the second-dimension column (and not after the first dimension), so that “one-and-a-half ” liquid chromatographs are needed to assemble one comprehensive two-dimensional one. The result of a comprehensive twodimensional separation is a series of many (for example, 100) fast second-dimension chromatograms. These usually are combined into a data matrix, which then can be displayed as a contour plot (see Figure 2) or color plot that displays peak intensity as a function of the retention times in the first and second dimensions (3). In
Table of Contents Feed for the Digital Edition of LCGC The Peak - April 2008 LCGC The Peak - April 2008 Contents LC3LC: Comprehensive Two-Dimensional Liquid Chromatography Split Injections in Gas Chromatography: How to Reduce Inlet Discrimination A Simple and Solvent-Free Method for Determining Tetracyclines in Prawns Industry News Events Education LCGC The Peak - April 2008 LCGC The Peak - April 2008 - LCGC The Peak - April 2008 (Page 1) LCGC The Peak - April 2008 - LCGC The Peak - April 2008 (Page 2) LCGC The Peak - April 2008 - LCGC The Peak - April 2008 (Page 3) LCGC The Peak - April 2008 - Contents (Page 4) LCGC The Peak - April 2008 - Contents (Page 5) LCGC The Peak - April 2008 - Contents (Page 6) LCGC The Peak - April 2008 - LC3LC: Comprehensive Two-Dimensional Liquid Chromatography (Page 7) LCGC The Peak - April 2008 - LC3LC: Comprehensive Two-Dimensional Liquid Chromatography (Page 8) LCGC The Peak - April 2008 - LC3LC: Comprehensive Two-Dimensional Liquid Chromatography (Page 9) LCGC The Peak - April 2008 - LC3LC: Comprehensive Two-Dimensional Liquid Chromatography (Page 10) LCGC The Peak - April 2008 - LC3LC: Comprehensive Two-Dimensional Liquid Chromatography (Page 11) LCGC The Peak - April 2008 - LC3LC: Comprehensive Two-Dimensional Liquid Chromatography (Page 12) LCGC The Peak - April 2008 - LC3LC: Comprehensive Two-Dimensional Liquid Chromatography (Page 13) LCGC The Peak - April 2008 - LC3LC: Comprehensive Two-Dimensional Liquid Chromatography (Page 14) LCGC The Peak - April 2008 - LC3LC: Comprehensive Two-Dimensional Liquid Chromatography (Page 15) LCGC The Peak - April 2008 - Split Injections in Gas Chromatography: How to Reduce Inlet Discrimination (Page 16) LCGC The Peak - April 2008 - Split Injections in Gas Chromatography: How to Reduce Inlet Discrimination (Page 17) LCGC The Peak - April 2008 - Split Injections in Gas Chromatography: How to Reduce Inlet Discrimination (Page 18) LCGC The Peak - April 2008 - Split Injections in Gas Chromatography: How to Reduce Inlet Discrimination (Page 19) LCGC The Peak - April 2008 - A Simple and Solvent-Free Method for Determining Tetracyclines in Prawns (Page 20) LCGC The Peak - April 2008 - A Simple and Solvent-Free Method for Determining Tetracyclines in Prawns (Page 21) LCGC The Peak - April 2008 - A Simple and Solvent-Free Method for Determining Tetracyclines in Prawns (Page 22) LCGC The Peak - April 2008 - A Simple and Solvent-Free Method for Determining Tetracyclines in Prawns (Page 23) LCGC The Peak - April 2008 - A Simple and Solvent-Free Method for Determining Tetracyclines in Prawns (Page 24) LCGC The Peak - April 2008 - A Simple and Solvent-Free Method for Determining Tetracyclines in Prawns (Page 25) LCGC The Peak - April 2008 - A Simple and Solvent-Free Method for Determining Tetracyclines in Prawns (Page 26) LCGC The Peak - April 2008 - Industry News (Page 27) LCGC The Peak - April 2008 - Events (Page 28) LCGC The Peak - April 2008 - Events (Page 29) LCGC The Peak - April 2008 - Education (Page 30) LCGC The Peak - April 2008 - Education (Page 31) LCGC The Peak - April 2008 - Education (Page 32)
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