Protection of terpenes against oxidative and acid decomposition on adsorbent cartridges

Sampling of monoterpenes from air on the 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, a-pinene and ~-pinene may be converted to camphene, limonene, p-cymene and several minor monoterpenes. Pretreatment of the adsorbent cartridges with thiosulphate as an anti-oxidant and bicarbonate as a buffer were found to prevent decomposition and rearrangements. Applications to monoterpenes emitted from kraft, thermo-mechanical, and sulphite pldp industries are presented