Comprehensive two-dimensional liquid chromatography

Abstract Despite it being introduced a couple of decades ago, comprehensive two-dimensional LC (LC × LC) techniques are still considered innovative methods and are continuously subjected to several modifications. The major benefit is that the separation capacities of each dimension are multiplied, thus offering a high peak capacity deemed as necessary to resolve samples of great complexity. In this chapter, theoretical and practical aspects related to the development of LC × LC methods are covered with particular emphasis to instrumental set-up and availability of novel stationary phases. The possibility to improve orthogonality for reversed phase × reversed phase separations with so-called “smart gradients” is also pointed out.