POLYPHENYLENESULFIDE, NOXON(R), AN OZONE SCAVENGER FOR THE ANALYSIS OF OXYGENATED TERPENES IN AIR

During sampling, oxygenated terpenes may undergo decomposition through reaction with atmospheric ozone. We have studied their ozonolytic dec omposition during preconcentration on Tenax. The saturated terpenoids 1,8-cineole, bornyl acetate nopinone and pinonaldehyde are practically unaffected by ozone in the range of 8 to 120 ppbv. Compounds which co ntain one or more C-C double bonds are decomposed in the order: linalo ol approximate to citronellal approximate to 6-methyl-5-hepten-2-one > citral > 4-acetyl-1-methylcyclohexane > 3-(1-methylethenyl)-6-oxo-hep tanal > myrtenal approximate to 2-methyl-3-buten-2-ol. The degree of d ecomposition varies from 0 to 5% for the least reactive to 80 to 90% f or the most reactive compounds. A broad range of material was investig ated as potential ozone scavengers. By using the polymer noXon (polyph enylenesulfide) all the investigated compounds could be sampled with q uantitative recoveries even at high ozone mixing ratios (95-110 ppbv). This ozone scrubber was tested for sampling of terpene oxidation prod ucts on Tenax and dinitrophenylhydrazine impregnated C-18-silicagel ca rtridges. Recoveries from 85 to 110% were obtained for all investigate d compounds. The method was used for the analysis of oxidation product s of terpenes in ambient air in three campaigns. Attention was focused on nopinone From beta-pinene, pinonaldehyde from alpha-pinene, 3-(1-m ethylethenyl)-6-oxo-heptanal and 4-acetyl-1-methyl-cyclohexane from li monene, and 5-(1-methylethyl)-bicyclo[3.1.0] hexan-2-one from sabinene . Nopinone was the only product which could be frequently detected in ratios from 0 to 90% of the measured beta-pinene concentrations. Pinon aldehyde was encountered only once (30% of alpha-pinene) while the oth er products were not found. These data have to be seen as a first atte mpt to measure terpene oxidation products in the troposphere. (C) 1997 Elsevier Science Ltd.