No abstract

A new method of extracting essential oils from dried plant materials has been studied. By adding a microwave-absorption medium (MAM) to a reactor, solvent-free microwave extraction (SFME) was improved and can be used to extract essential oils from dried plant material without pretreatment. With a microwave irradiation power of 85 W it took only approximately 30 min to extract the essential oils completely. The whole extraction process is simple, rapid, and economical. Three types of MAM, iron carbonyl powder (ICP), graphite powder (GP), and activated carbon powder (ACP), and two types of dried plant material, Illicium verum Hook. f. and Zingiber officinale Rosc., were studied. The results were compared with those obtained by use of conventional SFME, microwave-assisted hydrodistillation (MAHD), and conventional hydrodistillation (HD), and the conclusion drawn was that improved SFME was a feasible means of extracting essential oils from dried plant materials, because there were few differences between the composition of the essential oils extracted by improved SFME and by the other methods.

No abstract

A GC-MS method was developed for identification and determination of menthol in three traditional Chinese medicinal herbs and their compound formulation, a granule for treating colds. Volatile oil was simultaneously distilled and extracted into ethyl ether in a unique glass extractor. The separation was performed on an HP-5 MS column. The standard addition method was used for quantitative determination of menthol content in herbal materials and in the granule. A component in the samples was chosen as the internal standard. The contents were calculated with the ratio of peak area percentage. Menthol was identified as the main component in Mentha haplocalyx Briq., and also existed in spikes of Schizonepeta tenuifolia Briq., Folium perilla frutescens (L.) Britt. and granules. The quantitative calibration range was 0.21-10.5 mg/mL. Good precision was demonstrated by an RSD < 4.0%. The mean content of menthol in Mentha haplocalyx Briq., spikes of Schizonepeta tenuifolia Briq., Folium perilla frutescens (L.) Britt. and granules was 121, 0.234, 1.03 and 1.84 mg/kg respectively.

No abstract