ANALYSIS OF MONOTERPENES FROM CONIFER NEEDLES USING SOLID-PHASE MICROEXTRACTION

The applicability of solid phase microextraction (SPME) to the headspa ce analysis of monoterpene hydrocarbons from conifer needles was exami ned. To this end, the influences of fiber coating thickness, exposure time, and exposure temperature on the enrichment of the different mono terpene hydrocarbons were investigated, The distribution constants bet ween polydimethylsiloxane fiber and gas phase at a given temperature w ere found to be very different, A relation is therefore derived to cal culate the distribution constants of substances not available from the ir Kovats retention indices. A slightly different approach could be th e use of so-called ''relative distribution factors'', not considering the actual volume of fiber coating. In view of the different enrichmen t conditions in SPME as well as the general problems of headspace anal ysis, a comparison with a completely different method of sample prepar ation is presented, Furthermore, some applications of SPME to the anal ysis of monoterpenes from pine needles are given.