Determination of biogenic organic compounds in airborne particles by solvent extraction, derivatisation and mass spectrometric detection

Atmospheric oxidation of biogenic hydrocarbons such as monoterpenes is believed to be a globally significant source of aerosols. Secondary and primary biogenic hydrocarbons were determined in airborne particles. The particles were collected on quartz fibre filters in summer 2001 in a Norway spruce forest (Fichtelgebirge, Germany) at two different heights. The filters were Soxhlet extracted, the extract was concentrated and separated into five fractions with different polarity after flash chromatography and then measured with GC-MS. The first, second and third fractions were measured without derivatisation, the fourth fraction was silylated with BSTFA and the fifth fraction was methylated with BF3-Methanol. Many single compounds were detected and the highest concentrations were found for the polar components, especially for the dicarboxylic acids. Further quantified compounds include alkanes, ketones, aldehydes and carboxylic acids. Of special interest were the terpene oxidation products as pinonaldehyde, norpinic acid, pinic acid and pinonic acid. Typical concentrations of single compounds were in the sub ng m−3 range. Concentrations of terpene oxidation products are low in comparison to the terpene concentrations. More primary than secondary biogenic organic compounds were identified.