A Cascade Air Sampler with Multi-nozzle Inertial Filters for PM0.1

We applied a 3-nozzle geometry to the inertial filter unit of a previously developed cascade air sampler, which originally consisted of a 4-stage (PM10/2.5/1/0.5) impactor, and an inertial filter unit embedded in a single circular nozzle (for PM0.1), and compared its performance against that of a single-nozzle inertial filter unit. The multi-nozzle design enabled the collection of multiple samples and the analysis of multi-chemical particle components in the size range of 0.1-0.5 mu m. The total carbon was analyzed to determine the uniformity of the PM0.1 collected on a filter downstream from the inertial filter unit in both samplers, and the differences between the individual nozzles of the 3-nozzle unit as well as those between the 1- and 3-nozzle units were identified based on the chemical composition. After adjusting the quantity of the fibers in each inertial filter (one per nozzle) of the 3-nozzle sampler with care on the fiber packing uniformity, the 3-nozzle and 1-nozzle units exhibited similar separation performance, with approximately a 5% lower pressure drop for the former. The differences in the collected particle mass and the total carbon between the individual nozzles of the multi-nozzle unit and between the single- and multi-nozzle units were found to be less than 10%. However, the 3-nozzle unit uniformly collected particles regardless of the loaded particle mass, whereas its 1-nozzle counterpart exhibited non-uniform collection with higher loads. These data, together with the lower pressure drop, show that the multi-nozzle design has practical applicability, thus opening possibilities for chemically analyzing PM0.1.