Development and validation of a high-volume, low-cutoff inertial impactor

A low-cutoff high-volume conventional impactor has been designed. This samp ler uses a slit shaped acceleration jet and operates at 1100 L/min. The imp action substrate is polyurethane foam (PUF). The impactor collection effici ency was characterized using polydisperse particles, and the 50% size cutof f point was 0.12 mu m. Losses within the sampler were also characterized an d were less than 10%. The use of polyurethane foam (PUF) as a substrate has the following advantages: (1) PUF has a very high particle collection effi ciency over a large range of particle sizes, even under conditions of heavy particle loading, as compared to other impaction substrates, such as flat plates and less porous membranes, which typically are subject to significan t bounce-off and reentrainment; (2) no oil or grease coating is required, s o potential interferences of impurities within such coatings are avoided wh en chemical, biological, and toxicological tests are performed on the colle cted particles; (3) PUF itself is chemically inert, minimizing interference with any of these tests; (4) because of the high flow rate of 1100 L/min, a large amount of particles can be collected in a short period of rime on a relatively small surface of substrate, facilitating recovery of the collec ted particles for the different tests; and (5) a large amount of particles can be collected on a relatively small collection surface and easily extrac ted with small amounts of water or organic solvents. This method will be su itable for the collection of large amounts for toxicological studies and an alysis of organic aerosols, which is not possible with other high-volume sa mplers that utilize large filtration surfaces.