Abstract
A gel permeation high-performance liquid chromatographic (GPC-HPLC) method is presented to determine trace amounts of asphalt in particulate matter from asphalt-paved roads. A 0. 025-2-g amount of particulate sample was extracted for 6 h with 110 ml of 4/1 benzene/ethanol in a Soxhlet extractor. The extract was filtered with a Toyo Roshi No.5C filter paper, concentrated to dryness on' a water bath and heated at 100° for 2 h. The residue was dissolved in 2-10 ml of tetrahydrofuran (THF) and thus filtered with a cellulose menbrane filter (0.45μm). A 5-μl volume of the sample was analyzed by GPC-HPLC with fluorescene detection at λex 285 nm and λem 400 nm. The analytical column used was a 7. 5 mm i, d.× 50 cm stainless steel tube packed with JASCGJ Finepak Gel 101. The mobile phase was THF and the fl ow rate was 0.5 ml/min. The asphalt was quantified by peak height at the elution volume where components with 1, 000 of molecular weight were eluted. The detection limit of asphalt, defined as tenth the noise level, was 50 ng. Asphalt could be linearly determined in the range 0-8μg. The recovery obtained was 87% for a 5-μg level of asphalt spiked to diesel engine soot with 5% relative standard deviation, and was 95-97% for a 0.5mg level of asphalt spiked to airborne particulate matter collected at a roadside. The organic substances in vehicle engine soot and tire tread particulate did not interfere with the determination of asphalt in particulate matter from asphalt-paved roads.
