Assay of volatile organic compounds in urban air using passive sampling and gas chromatography coupled to mass spectrometry

Abstract

Volatile organic compounds (VOCs) include a wide range of air pollutants emitted from diverse anthropogenic and biogenic sources. VOCs in air have great importance as they have direct and indirect effects on climate change, ecosystems and human health. The goal of this study was optimization of sampling, sample preparation and quantification of volatile organic compounds in air and implementation of the method for air monitoring in Skopje, Macedonia. Radiello® passive samplers with special radial design, that provides higher capacity and faster sampling rates than traditional passive samplers were used for VOCs sampling. Different sampling times were tested and dichloromethane was selected as an efficient solvent for desorption and further analysis. GC-MS method for separation was optimized and anisole as an internal standard was used for semi-quantification. The optimized method was then applied for analysis of extracts of real samples of air taken on Radiello® passive samplers placed on several locations in Skopje in two consecutive months. More than 30 compounds were identified and semi-quantitatively determined using anisole as an internal standard. Most of them can be attributed to transport fuels and derivatives such as BTEX (benzene, toluene, ethyl benzene and xylenes) and alkanes, such as undecane, dodecane, tridecane and tetradecane. In addition, naturally occurring terpenes were found (α-pinene and limonene) in many samples that can originate from both natural sources or domestic cleaning products. The concentrations of the detected compounds have been below the established reference concentrations by EPA that cause critical effects but they should be continuously monitored. The long-term goal is to set up efficient, accurate and sensitive methods for monitoring VOCs concentrations throughout the year to reveal the sources of outdoor pollution in urban areas and plan control measures for their reduction.