Measurement of secondary products during oxidation reactions of terpenes and ozone based on the PTR-MS analysis: effects of coexistent carbonyl compounds.

Yusuke Ishizuka,Yukio Yanagisawa,Atsushi Mizukoshi,Miyuki Noguchi,Masahiro Tokumura

doi:10.3390/ijerph7113853

Abstract

Continuous measurements using proton transfer reaction mass spectrometry (PTR-MS) can be used to describe the production processes of secondary products during ozone induced oxidation of terpenes. Terpenes are emitted from woody building materials, and ozone is generated from ozone air purifiers and copy machines in indoor environments. Carbonyl compounds (CCs) are emitted by human activities such as smoking and drinking alcohol. Moreover, CCs are generated during ozone oxidation of terpenes. Therefore, coexistent CCs should affect the ozone oxidation. This study has focused on the measurement of secondary products during the ozone oxidation of terpenes based on the use of PTR-MS analysis and effects of coexistent CCs on oxidized products. Experiments were performed in a fluoroplastic bag containing α-pinene or limonene as terpenes, ozone and acetaldehyde or formaldehyde as coexistent CCs adjusted to predetermined concentrations. Continuous measurements by PTR-MS were conducted after mixing of terpenes, ozone and CCs, and time changes of volatile organic compounds (VOCs) concentrations were monitored. Results showed that, high-molecular weight intermediates disappeared gradually with elapsed time, though the production of high-molecular weight intermediates was observed at the beginning. This phenomenon suggested that the ozone oxidation of terpenes generated ultrafine particles. Coexistent CCs affected the ozone oxidation of α-pinene more than limonene.

Highlights

Ozone is transported from outdoor environments to indoor environments by ventilation, and indoor ozone concentrations are typically about 20–70% of concurrent outdoor levels [1]
This study focuses on the effects of the incorporation of coexistent Carbonyl compounds (CCs) in residential indoor environments into ozone-terpenes oxidation reactions based on proton transfer reaction mass spectrometry (PTR-MS) analysis. α-Pinene and limonene were used as model terpenes, and acetaldehyde and formaldehyde were used as model coexistent CCs in residential indoor environments
Effects of coexistent CCs on the ozone oxidation of terpenes were investigated by the measurement of secondary products during the ozone oxidation of terpenes based on PTR-MS analysis

Summary

Introduction

Ozone is transported from outdoor environments to indoor environments by ventilation, and indoor ozone concentrations are typically about 20–70% of concurrent outdoor levels [1]. Outdoor ozone concentrations reach at maximum 6.12 × 10−2–2.04 × 10−1 ppm (120–400 μg m−3) [2]. Air cleaners using ozone have been widely used in residences in recent years, and they have been believed indoor sources of ozone [3,4,5]. According to the literature [9], ozone concentrations in poorly ventilated rooms which contained electrostatic air cleaners and photocopying machines were up to 2.50 × 10−1 ppm (490 μg m−3). Ozone concentrations in residences are believed higher than estimated from outdoor ozone concentration and indoor ozone concentrations should be especially high around printers, photocopiers and air purifiers [10,11]

Methods

Results

Conclusion