Use of two different coating temperatures for a cold fiber headspace solid-phase microextraction system to determine the volatile profile of Brazilian medicinal herbs

In this study, the experimental extraction conditions on applying headspace solid-phase microextraction and cold fiber headspace solid-phase microextraction (CF-HS-SPME) procedures to samples of six medicinal herbs commonly found in southern Brazil were optimized. The optimized conditions for headspace solid-phase microextraction were found to be an extraction temperature of 60 degrees C and extraction time of 40 min. For CF-HS-SPME, the corresponding values were 60 degrees C and 15 min. In the case of the coating temperature for the CF-HS-SPME system, two approaches were investigated: (i) Temperature of 5 degrees C applied during the whole extraction procedure; and (ii) the use of two fiber temperatures in the same extraction procedure with the aim of extracting the volatile and semivolatile compounds, the ideal condition being 60 degrees C for the first 7.5 min and 5 degrees C for the final 7.5 min. The three extraction procedures were compared. The CF-HS-SPME procedure had good performance only for the more volatile compounds whereas the strategy using two coating temperatures in the same procedure showed good performance for all compounds studied. It was also possible to determine the profile for the volatile fraction of each herb studied applying this technique followed by GC-MS.