Ionic Liquids in Monolithic LC Separations: ILs as Mobile Phase Additives in Separation of Antiretrovirals

摘要

Ionic liquids (ILs) and monolithic materials are the emerging trends in chromatographic separations. In the present investigation 3-methylimidazolium cation-based ionic liquids were evaluated as mobile phase additives to check their compatibility with monolithic columns for separation of antiretroviral drugs by RP-HPLC. Effect of their concentration, polarity and viscosity on peak asymmetry and resolution was studied. Multiple interactions of ILs with analytes as well as stationary phase were found to be beneficial in optimizing the separation of antiretrovirals. ILs viz., BMITB and EMIMS were found to be compatible with the monolith column for separation of ARVs because of their polar nature of cation and medium chaotropic character of the anions. The two effects i) silanol screening by the cation and ii) ion-pairing by anion, have shown beneficial influence on the chromatographic separations. However, the choice of the right IL depends on viscosity, polarity, hydrophobicity, and the nature of anions.