Retention of 3,5-dinitrobenzoyl derivatives of linear alcohol polyethoxylates in reversed-phase liquid chromatographic system with acetonitrile-water mobile phase.
The influence of mobile phase composition (acetonitrile-water ratio) on the separation of derivatised linear alkyl polyethoxylates (LAEs) is evaluated using thermodynamic quantities (Gibbs energy, enthalpy and entropy). In comparison to homologue series of alcohols oligomers of LAEs show irregular chromatographic behaviour that is demonstrated in irregular changes of thermodynamic quantities. It might be explained considering an influence of some of the following processes or their combinations on the retention of LAEs. These processes are solvation of oxyethylene chains in mobile phase, their interaction with silanols on silica surface of stationary phase and possibly their conformation changes. The composition of a mobile phase affects the mentioned processes and that is why the retention of LAEs is strongly (for the reversed-phase system unusually) sensitive to this composition in the studied range (volume fraction of acetonitrile phi = 0.90, 0.96 and 0.98). The experimental data also support the idea of the active role of stationary phase in the reversed-phase system.
Lemr
Karel
K
Department of Analytical Chemistry, Palacký University, Tr. Svobody 8, 771 46 Olomouc, Czech Republic. lemr@risc.upol.cz
Sevcík
Juraj
J
Hlavác
Jan
J
D000097:Acetonitriles / Q000737:chemistry; D000438:Alcohols / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000379:methods*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
D000097:Acetonitriles; D000438:Alcohols; D014867:Water; C032159:acetonitrile