Analysis of the Volatile Compounds in Thymus vulgaris L. Using Improved HS-SPME-GC-MS and Comparison with Conventional Methods

In this study, gas chromatography-mass spectrometry (GC-MS) following microwave distillation and solid-phase microextraction (MD-SPME) was developed for the analysis of volatile constituents from the aerial parts of Thymus vulgaris L. In order to improved headspace method, microwave powers; irradiation times and SPME fibers coating were studied. The optimal experiment parameters obtained were: 100 mu m PDMS, a microwave power of 400 W and an irradiation time of 5 min. MD-SPME was compared with headspace solid-phase microextraction (HS-SPME) and conventional hydrodistillation (HD) for the extraction of volatile compounds in Thymus vulgaris L. A comparative qualitative and quantitative study on the composition of volatile compound was carried out. Thymol, p-cymene, gamma-terpinene and carvacrol were identified as major constituents of this plant in all methods. The relative standard deviation (R.S.D) values of less than 7 % showed that the MD-SPME method has good repeatability. It has been shown the extraction of volatile compounds from Thymus vulgaris L. with MD-SPME was better in terms of energy saving, extraction time, plant material, oxygenated fractions and product quality.