Determination of Teucrium chamaedrys volatiles by using direct thermal desorption–comprehensive two-dimensional gas chromatography–time-of-flight mass spectrometry

The direct qualification and quantification of the volatile components of Teucrium chamaedrys was studied using a direct thermal desorption (DTD) technique with comprehensive two-dimensional (2D) gas chromatography–time-of-flight mass spectrometry (GC × GC–TOF/MS). The GC × GC separation chromatographically resolved hundreds of components within this sample, and with the separation coupled with TOF/MS for detection, high probability identifications were made for 68 compounds. The quantitative results were determined through the use of internal standards and the desorption of differing amounts of raw material in the injector. The highest yield of volatile compounds (0.39%, w/w) was obtained at 150 °C thermal desorption temperature using 1.0 mg of dried sample placed in a glass injector liner when studied over the range 1.0–7.0 mg. Lowest yield of 0.33% (w/w) was found for the largest sample size of 7.0 mg. Relative standard deviation (RSD) for 10 replicates at each size sample were in the range 3.9–21.6%. The major compounds identified were β-pinene, germacrene D, α-pinene, α-farnesene, α-gurjunene, γ-elemene and γ-cadinene. All identified compounds were quantified using total ion chromatogram (TIC) peak areas. DTD is a promising method for quantitative analysis of complex mixtures, and in particular for quantitative analysis of plant samples, which can yield data without the traditional obligation for costly and time-consuming extraction techniques.