Two-dimensional liquid chromatography (2D-LC) is finding increasingly wide application to the analysis of mixtures of moderate to high complexity. Many industries are developing increasingly complex products that are challenging the separation capabilities of state-of-the-art 1D-LC and need new analytical methodologies with substantially more resolving power, 2D-LC meets that need. This text, organized by two leaders in the field, establishes a sound fundamental basis for the principles of the technique, followed by a discussion of important practical considerations. Finally, applications of 2D-LC in several fields ranging from pharmaceutical analysis to polymer science are summarized. Key Features:Demonstrates the conditions under which a 2D-LC method should be considered as an alternative to a 1D-LC method. Establishes a sound fundamental basis of the principles of the technique, followed by guidelines for method optimization. Provides a single source for technical knowledge advances and practical guidance described in recent literature. Assists with the initial decision to develop a 2D-LC method. Guides the reader in developing a high-quality method that meets the needs of their application.