Retention study of some cation‐type compounds using bile acid sodium salts as ion pairing agents in liquid chromatography

Abstract

The possibility of forming ion-pairs between bile acids (sodium taurocholate, sodium taurodeoxycholate and sodium taurochenodeoxycholate) and different compounds (pralidoxime, obidoxime and pyridostigmine) having a cationic character has been studied in reversed-phase liquid chromatography (RP-LC). This study can be useful in understanding the role of bile acids in the transport of ionic species through hydrophobic membrane. The present study focused on the influence of mobile phase composition on the retention parameters of chosen compounds (percentage of acetonitrile, pH of aqueous component or ionic strength). For constant concentration of bile acids in aqueous component of mobile phase the functional dependencies between the logarithm of the retention factor (k) and the methanol content in the mobile phase followed a binomial pattern (U-shaped), with a minimum positioned within the interval 70-85% methanol.

Structural modifications of dicationic acetylcholinesterase reactivators studied under ion‐pairing mechanism in reversed‐phase liquid chromatography

“…. In case of dicationic oximes, pH plays a major role in stabilization of the cationic form, as it has been demonstrated theoretically and experimentally in the previous studies using bile acids as IPA – . The equilibrium between oxime and nitroso group from these molecules can be in favor of oxime form, which is able to participate in the IP mechanism, or in favor of nitroso form, which does not participate to this mechanism.…”

“…It is the aim of this work to study the influence of the main elution parameters on chromatographic behavior for several acetylcholinesterase reactivators with dicationic character under IP mechanism due to structural modifications taking place in analyte molecules. This could be useful either for analytical purposes or for a better understanding of the interaction of these compounds with biochemical compounds during their absorption and transport as dependent on the structural modification due to the solvation environment . These compounds are interesting for studying the IP mechanism due to the fact that they are involved in tautomeric equilibria, which can influence the entire retention process.…”

LC–MS/MS Approaches for The Assay of Bis -Quaternary Pyridinium Oximes Used as Ache Reactivators in Biological Matrices

“…For the IPRP mechanism, sodium octyl sulphonate is generally chosen as ion pairing agent [7,15,17]. Bile acids sodium salts have been also successfully used as ion pairing agents for quaternary ammonium oximes [19]. Unusual retention behavior of some cationic type aldoximes was reported under the IPRP mechanism [20].…”