Perfecting the separation and measurement of calixarene Dioctyl Calix-[4]-Crown-6 by high performance liquid chromatography with UV detection

Calix-[4]-crown-6 display an exceptional selectivity towards cesium, due to their preorganization and their complementarity between the size of the crown and that of this cation. Their application in the field of nuclear industry allows this element to be very selectively extracted from nitric solutions obtained from the dissolution of nuclear spent fuel. The studies dealing with extraction of cesium by calixarenes involve knowing how to measure this complexing molecule into its solvent. The solvent is a mixture of Nitro-2-PhenylHexylEther (NPHE) and Tetra Propylene Hydrogenated (TPH). Since TPH is saturated, and thus, non UV absorbing molecule, its presence into the mixture will not interfere; on the other hand, NPHE, which exhibits chemical fonctionalities and an hydrophobicity quite similar to those of calixarene, must be separated from the complexing molecule. We have determined the conditions of separation between calixarene and its solvent by using the adsorption chromatographic mode over silica, associated with an organic eluent composed of hexane and isopropanol. In these conditions, separation of the calixarene from NPHE is accomplished in less than 8 minutes.