Use of cyclodextrins for the separation of monoterpene isomers by micellar electrokinetic capillary chromatography

The micellar electrokinetic capillary chromatographic method for the determination of monoterpenes such as camphene, α‐pinene, β‐pinene, γ‐terpinene, α‐terpinene, terpinolene and p‐cymene was established. Addition of cyclodextrins (CDs) to the buffer solution permits the separation of these monoterpenes. The separation is dependent on the type of CD, and gamma‐CD was the most effective cyclodextrin, in the method here developed. The method permits low concentrations of monoterpenes to be separated and detected. The addition of an organic solvent (acetonitrile) as modifier in the buffer (10 m M NaH 2 PO 4 , 6 m M Na 2 B 4 O 7 , 50 m M SDS, 7 m M de γ‐CD) allowed this separation. The analysis was performed with a positive power supply of 20 kV at a temperature of 25°C. The samples were hydrostatically (5 s) introduced into the anodic end of the capillary and electropherograms were recorded at 200 nm. This method could be highly suitable for the separation and determination of monoterpenes in essential oils of leaves, and the flowers of marjoram and oregano among other real samples.