Comprehensive two-dimensional liquid chromatography (LC×LC) has become an important technique for the detailed analysis of complex samples. In LC×LC, samples are separated on two columns consecutively to obtain much higher separation power and therefore more detailed chemical information. One of the main challenges in modern LC×LC involves modulation –the transfer of fractions between the two columns. To improve the performance and application range of LC×LC, alternative modulation strategies are therefore required. This project will focus on the evaluation of thermal modulation in LC×LC, adopting an approach used advantageously in comprehensive gas chromatography (GC×GC). Two main methodologies will be investigated. In the first instance, the use of high-retention traps with high-temperature elution will be optimized for LC×LC separations. Secondly, a novel approach based on the use of temperature responsive LC (TRLC) will be explored. TRLC utilizes modified stationary phases which change their retention properties as a function of temperature. In this project, this property of TRLC will be exploited, first of all as an aqueous first dimension separation in LC×LC, and secondly as a means of obtaining effective thermal modulation in LC×LC. New TRLC phases will be designed for this purpose, and instrumental and practical aspects of thermal modulation will be elucidated. The project will exploit established expertise in TRLC and LC×LC of the two research groups.