Identification of methoxylated phenols as candidate tracers for atmospheric wood smoke pollution

Abstract

More than 70 organic compounds have been identified in unfractionated methylene chloride extracts of soot from residential wood stoves by a combination of capillary gas chromatography coupled with low-resolution mass spectrometry (GC/MS), GC coupled with high-resolution mass spectrometry, and chemical ionization mass spectrometry with deuteriated methanol as the reagent gas. Thirty of the species are derivatives of guaiacol (2-methoxyphenol) and syringol (2,6-dimethoxyphenol), which result from the pyrolysis of wood lignin. Soots from hardwood and pine show similar proportions of the syingol derivatives, but pine soot has much higher proportions of the guaiacol derivatives. Samples collected onto filters backed up by polyurethane foam (PUF) plus in the cooled smoke plume showed that some of the methoxylated phenols were primarily in the vapor phase, while the majority were associated with the particulates. These species are expected to be unique to wood smoke in urban atmospheres and are therefore suggested as tracers for atmospheric wood smoke pollution.