Biogenic volatile organic compounds (BVOC) in ambient air over Hong Kong: Analytical methodology and field measurement

In this paper, an analytical method using a simple semi-manual cryo-trap technique coupled to gas chromatograph with flame ionisation detector (GC-FID) was developed for the determination of biogenic volatile organic compounds (BVOC) in ambient air. Five common BVOC species have been tested, including isoprene and 4 monoterpenes, i.e. α-pinene, β3-pinene, 3-carene (Δ) and limonene. The detection limits were estimated to be about 20ppt for isoprene and 10ppt for monoterpenes, with sample injection volume of 50mL. Based on vegetation types, field measurement work was conducted over urban and rural sites of Hong Kong during summer and winter of 2007. Canister sampling technique was applied in the field measurement. Isoprene contents in rural ambient air were found to be in the range of 60~1560 ppt in winter and 260~3270 ppt in summer, respectively. However, in the measurement of monoterpenes, due to their extremely low concentration in the air samples, only βS-pinene and limonene were detected by the developed analytical method.