ABSTRACT
Increasing the separation efficiency and understanding the interactions associated with the columns and the stationary phases are some of the major objectives of fundamental studies on liquid chromatography. The separation of isotopic compounds is significant in separation science for how it illustrates the extremely high ability of high performance liquid chromatography systems, and has its own significance, too, as a longtime target of scientific curiosity. Isotopic separation is an interesting subject for separation science by itself because of the high similarity in the solute structure. Fundamental information on molecular interactions will be helpful for understanding the retention behaviors of various solutes in combination with diverse stationary phases and mobile phases. Difficult separations have often been carried out by recycle chromatography using a series of several columns to allow the solute mixture band to go through the columns many times before being eluted out.
