Ozone removal in the sampling of parts per billion levels of terpenoid compounds: An evaluation of different scrubber materials

Some reactive volatile organic compounds (VOCs) are prone to degradation du ring sampling in an ozone-rich environment. A wide variety of different che micals have been used to remove the ozone prior to sampling, but the possib ility of interference by such chemicals with the sampled VOCs has not been thoroughly examined. In the present investigation, the retention/degradatio n of four terpenes alpha -pinene, beta -pinene, 3-carene, and limonene) and isoprene together with some of their oxidation products (alpha -pinene oxi de, nopinone, 4-acetyl-1 -methylcyclohexene (AMCH) methylglyoxal, and metha crolein) has been studied, using Various ozone-removing chemicals in an att empt to evaluate their poten tial as ozone scrubbers in the sampling of amb ient air. The chemicals included in this first screening and their ozone-re moving capacity are as follows: Kl, MnO2, and Na2SO3 removed ozone for more than 24 h when exposed to 73-78 ppb (150-160 mug/m(3)) at a sampling flow rate of 500 mL/min. Silanized poly(1,4-phenylene sulfide) (PFS) removed ozo ne far 5 h, unsilanized PFS removed ozone for 1 h and 50 min, and Na2S2O3 r emoved ozone for 20 min. The recovery of the selected compounds with the di fferent scrubbers was >95% for ail compounds for Kl; >95% for the terpenes oxidation products; >90% for the terpenes and isoprene for PFS; >90% for th e terpenes and isoprene for MnO1 on copper nets, Na2SO3, and Na2S2O3; and < 90% for the terpenes and isoprene for carulite (a commercial mixture betwee n MnO2, CuO, and Al2O3), CuO, and indigo carmine.