Separation and analysis of the major constituents of cloves by micellar electrokinetic chromatography

A micellar electrokinetic chromatographic method was developed and applied for the first time to the separation and quantification of the main components of cloves, namely eugenol and beta-caryophyllene. The analytes were separated in less than ten minutes in an unmodified fused silica capillary (effective length: 40.0 cm) using a background electrolyte composed of 25 mM carbonate buffer (pH 10.0) and 60 mM sodium dodecylsulfate. Analyte concentrations were determined in clove oil and in methanolic clove extracts after simple sequential dilution with methanol and background electrolyte, and the resulting electropherograms showed no interference due to other components. Precision assays gave satisfactory results, with mean standard deviation of peak areas lower than 4.7% (lower than 1.5% for migration times). The eugenol content of a commercial clove oil was about 70% (RSD% = 3.2), while that of beta-caryophyllene was about 15% (RSD% = 4.2); in clove extracts, on the other hand, eugenol was approximately 15% (RSD% = 4.7) and beta-caryophyllene 4% (RSD% = 5.1). Accuracy was also good (mean recovery >98%).