Fast quantitative determination of volatile constituents in fennel by headspace-gas chromatography

A headspace-gas chromatography method for analyzing volatile constituents in fennel (Foeniculum vulgare) fruits and leaves has been developed. The use of the full evaporation technique (FET) in combination with short chromatographic run times allows over 100 samples per day to be analyzed. Dependently on the sample type, little or virtually no sample preparation is needed. The method was validated for the major volatile constituents present in fennel fruits: α-pinene, α-phellandrene, limonene, fenchone, estragole and trans-anethole. The method has proven to be linear from sub-microgram levels to 1000 μg for each analyte studied present in the sample. The limits of detection (LOD) and the limits of quantitation (LOQ) ranged from 0.07 to 0.2 μg and from 0.2 to 0.5 μg, respectively. Anisaldehyde, a degradation product of trans-anethole, was also included in the study. Due to its linearity, sensitivity and efficient separation the method use could be extended to other compounds present in fennel as well. Oxidation stability of trans-anethole during headspace sampling was also assumed.