PROTECTION OF TERPENES AGAINST OXIDATIVE AND ACID DECOMPOSITION ON ADSORBENT CARTRIDGES

Sampling of monoterpenes from air on Tenax porous polymer may introduce analytical errors owing to oxidation and acid rearrangements on the adsorbent. Particularly terpenes which react rapidly with ozone, e.g. myrcene and limonene, are partially lost when sampling air with high photooxidant levels. On acidified adsorption cartridges, alpha-pinene and beta-pinene may be converted into camphene, limonene, p-cymene and several minor monoterpenes. Pretreatment of the adsorbent cartridges with thiosulphate as an antioxidant and hydrogencarbonate as a buffer were found to prevent decomposition and rearrangements. Applications to monoterpenes emitted from the kraft, thermo-mechanical and sulphite pulp industries are presented.