Dual CD system in capillary electrophoresis for direct separation of the four stereoisomers of agonist and antagonist melatoninergic ligands.
In this study, baseline separation of the stereoisomers of six tetrahydronaphthalenic derivatives (agonists and antagonists for the melatonin (N-acetyl-5-methoxytryptamin) binding sites) was successfully achieved using CE and CDs as chiral selectors. The method for the simultaneous chiral separation of the four stereoisomers uses a capillary dynamically coated with polyethylene oxide and a dual CD system. Optimisation was performed first upon the constituents of the CD system, by varying neutral and anionic CD type, size and concentration, at first in mono-CD systems and subsequently in dual neutral/anionic CD systems. Once these characteristics of the dual CD system were established, operational parameters such as voltage and temperature were then optimised. Under the optimal conditions (i.e. 1.5% w/v of highly S-beta-CD and 10 mM of gamma-CD in 25 mM phosphate buffer (pH 2.5) as the BGE, separation voltage 20 kV and a temperature of 25 degrees C), complete resolution of the six molecules was accomplished. Preliminary results for repeatability and the migration order of the optimised method are described.
Lipka
Emmanuelle
E
Laboratoire de Chimie Analytique, EA, Lille France.
Danel
Cécile
C
Yous
Saïd
S
Bonte
Jean-Paul
JP
Vaccher
Claude
C
D003505:Cyclodextrins / Q000737:chemistry*; D019075:Electrophoresis, Capillary / Q000379:methods*; D008550:Melatonin / Q000819:agonists / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D013237:Stereoisomerism; D013696:Temperature; D013764:Tetrahydronaphthalenes / Q000737:chemistry / Q000302:isolation & purification*
D003505:Cyclodextrins; D013764:Tetrahydronaphthalenes; D011092:Polyethylene Glycols; D008550:Melatonin