Insight into the retention mechanism on immobilized artificial membrane chromatography using two stationary phases.
The retention behavior of sixty structurally diverse drugs on two immobilized artificial membrane (IAM) columns, IAM.PC.MG and IAM.PC.DD2 types, at two pH values, 7.4 and 5.5, was established. Extrapolated to pure aqueous phase retention factors, logkw(IAM), were determined and the role of acetonitrile as organic modifier was explored, considering the relationships with the slopes, S, of the extrapolation procedure. Good interrelations between retention factors on the two IAM stationary phases were observed, although logkw(IAM.PC.DD2) values are generally higher than logkw(IAM.PC.MG). In order to investigate the underlying retention mechanism, relationships between IAM retention factors and lipophilicity, expressed as logP or logD at pH 7.4 were established. Electrostatic interactions were considered by introducing the positively and negatively charged molecular fractions as additional parameters in the logkw(IAM)/logD relationships. The positive contribution of these fractions supported the involvement of the electrostatic interactions in the retention mechanism. Special attention was given to the retention behavior of zwitterionic compounds and for compounds with special structural characteristics.
Laboratory of Pharmaceutical Chemistry, School of Pharmacy, University of Athens, Panepistimiopolis, Zografou, 157 71 Athens, Greece; Laboratory of Inorganic and Analytical Chemistry, School of Chemical Engineering, National Technical University of Athens, Iroon Polytechniou 9, 157 80 Athens, Greece. Electronic address: ftsop@central.ntua.gr.
Fotios
F
Tsopelas
Laboratory of Pharmaceutical Chemistry, School of Pharmacy, University of Athens, Panepistimiopolis, Zografou, 157 71 Athens, Greece.
Niki
N
Malaki
Laboratory of Pharmaceutical Chemistry, School of Pharmacy, University of Athens, Panepistimiopolis, Zografou, 157 71 Athens, Greece.
Theodosia
T
Vallianatou
Laboratory of Pharmaceutical Chemistry, School of Pharmacy, University of Athens, Panepistimiopolis, Zografou, 157 71 Athens, Greece.
Marios
M
Chrysanthakopoulos
Laboratory of Pharmaceutical Chemistry, School of Pharmacy, University of Athens, Panepistimiopolis, Zografou, 157 71 Athens, Greece.
Demetris
D
Vrakas
Laboratory of Inorganic and Analytical Chemistry, School of Chemical Engineering, National Technical University of Athens, Iroon Polytechniou 9, 157 80 Athens, Greece.
Maria
M
Ochsenkühn-Petropoulou
Laboratory of Pharmaceutical Chemistry, School of Pharmacy, University of Athens, Panepistimiopolis, Zografou, 157 71 Athens, Greece. Electronic address: tsantili@pharm.uoa.gr.
Anna
A
Tsantili-Kakoulidou
D002853:Chromatography, Liquid / Q000295:instrumentation* / Q000379:methods; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D008567:Membranes, Artificial; D004364:Pharmaceutical Preparations / Q000032:analysis; D055672:Static Electricity
D008567:Membranes, Artificial; D004364:Pharmaceutical Preparations
Electrostatic interactions; IAM.PC.DD2; IAM.PC.MG; Immobilized artificial membrane chromatography; Octanol–water partitioning