Influence of ionic liquids’ nature on chromatographic retention of benzimidazoles by RP HPLC

Abstract

One of the priority tasks of the pharmaceutical industry is to manufacturing high-quality, effective, and safe medicines. Thus, the interest in for searching biologically active compounds perspective for the creation of new drugs is growing. The aim of this work was to study the chromatographic behavior of benzimidazole and its firstly synthesized derivatives by reversed-phase–HPLC (RP-HPLC). The sorption of benzimidazole and its five derivatives from liquid solutions of various qualitative composition on octadecyl silica gel was studied by the method of RP HPLC. Mobile phases contained ionic liquids (IL) as an additive: 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ([BdMIM] [BF4]) and 1-butyl-3 methylimidazolium bromide ([BMIM] [Br]). The effect of eluent’s and ILs’ nature on benzimidazoles’ retention from six compositions of mobile phases at a ratio of H2O (or aqueous solution of IL)/organic modifier (acetonitrile or methanol) of 50/50 vol.% was studied. The standard changes in the enthalpy of the benzimidazoles’ transition from the aqueous-organic eluent to the octadecyl silica gel layer and the entropy components of the process were calculated based on the temperature dependences of the retention factors. A comparative analysis of the enthalpies’ and entropy components’ values of the sorption process for the studied benzimidazoles was carried out. Also the enthalpy–entropy dependences were considered.