Column temperature* is a useful but often overlooked variable in HPLC separations. In reversed phase (RP), retention generally decreases with increasing temperature. For this reason, higher temperature can often be successfully used to speed up a method’s run time. Furthermore, solvent viscosity decreases at higher temperatures, so pressure is lower and this allows for higher flow rates than would otherwise be feasible, further reducing run time.
In Aqueous Normal Phase (ANP) chromatography, (which can only be performed on Cogent TYPE-C™ columns) generally lower temperatures lead to lower analyte retention as opposed to reversed phase. In addition to reducing run time, temperature can also be explored as a tool for altering selectivity. It is more convenient than many other common ways to change selectivity, such as use of a different mobile phase or changing the column. In most cases however, you should start the method development process at room temperature.
* The control of temperature in an HPLC column is important and must be consistent throughout the entire column. For this reason, it is important to make sure that your equipment to control temperature is built for HPLC columns.