LAUSR

Abstract A solid-phase microextraction coupled with gas chromatography and mass spectrometry (SPME-GC-MS) method was developed to discriminate the two chemotypes of the medicinal herb Egletes viscosa. The optimization of the extraction conditions was carried out through factorial design and response surface methodology. The best conditions were achieved when the flower buds (0.33 g) using the divinylbenzene/carboxen/polydimethylsiloxane-coated fiber (DVB/CAR/PDMS, 50/30 µm) were extracted for 6.6 min at 40 °C, corresponding to an extraction time 30x shorter and a sample mass 300x lesser than the conventional method based on hydrodistillation (HD). Five out of 16 commercial samples were classified as chemotype A for presenting trans-pinocarveyl acetate as major compound (25.7-34.3%), while the others were from chemotype B for being richer in cis-isopinocarveyl acetate (27.4- 62.2%). This finding is in perfect agreement with the classification provided by HD-GC-MS. Regardless of the extraction method, the volatiles constituents were basically monoterpenoids and monoterpenes, but SPME extracted more compounds than HD (33 x 24). In addition, many of them were detected only by one of the extraction methods or fiber coating. Since our SPME method demonstrated to be able to discriminate the two chemotypes in a non-destructive way providing the volatile chemical composition, it will be helpful for chemical screening and quality control of raw materials for pharmaceutical and cosmetic purposes.