Porous polyurethane foam for use as a particle collection substrate in a nanoparticle respiratory deposition sampler

Abstract

Porous polyurethane foam was evaluated to replace the eight nylon meshes used as a substrate to collect nanoparticles in the Nanoparticle Respiratory Deposition (NRD) sampler. Cylindrical (25-mm diameter by 40-mm deep) foam with 110 pores per inch was housed in a 25-mm-diameter conductive polypropylene cassette cowl compatible with the NRD sampler. Pristine foam and nylon meshes were evaluated for metals content via elemental analysis. The size-selective collection efficiency of the foam was evaluated using salt (NaCl) and metal fume aerosols in independent tests. Collection efficiencies were compared to the nanoparticulate matter (NPM) criterion and a semi-empirical model for foam. Changes in collection efficiency and pressure drop of the foam and nylon meshes were measured after loading with metal fume particles as measures of substrate performance. Substantially less titanium was found in the foam (0.173 μg sampler−1) compared to the nylon mesh (125 μg sampler−1), improving the detection capabilities of the NRD sampler for titanium dioxide particles. The foam collection efficiency was similar to that of the nylon meshes and the NPM criterion (R2 = 0.98, for NaCl), although the semi-empirical model underestimated the experimental efficiency (R2 = 0.38). The pressure drop across the foam was 8% that of the nylon meshes when pristine and changed minimally with metal fume loading (~ 19 mg). In contrast, the pores of the nylon meshes clogged after loading with ~ 1 mg metal fume. These results indicate that foam is a suitable substrate to collect metal (except for cadmium) nanoparticles in the NRD sampler.

Development of an impinger method for sampling airborne nanocellulose

“…Particles larger than 10 μm are removed by an aluminum cyclone, and particles larger than 300 nm are removed by an impactor. Particles smaller than 300 nm are collected onto nylon screens (and in a more recent edition, reticulated foam (Mines et al, 2016)) via diffusion. The NRD sampler was designed to collect nanoparticles with an efficiency that mimics the deposition of particles smaller than 300 nm in the human lung.…”

Design and evaluation of a high-flowrate nanoparticle respiratory deposistion (NRD) sampler

“…Another personal nanoparticle sampler, the 2.5 L/min Nanoparticle Respiratory Deposition (NRD) sampler, is commercially available through Zefon International. The NRD consists of a respirable aluminum cyclone followed by an impactor designed to remove particles larger than 300 nm (Cena et al, 2011;Mines et al, 2016). The airborne nanoparticles passing through the impactor are collected in a diffusion stage consisting of eight nylon meshes with a collection efficiency mimicking the deposition of nanoparticles in the human respiratory tract (Cena et al, 2011).…”

“…The NRD sampler has a shortcoming of requiring long run times to collect enough nanoparticles for quantification. Moreover, the currently available model from Zefon International contains a series of nylon meshes in the diffusion stage, which contain consequential amounts of titanium (Mines et al, 2016). Recently, the 2.5 L/min NRD diffusion stage material was changed from a series of mesh screens to a polyurethane foam (Mines et al, 2016).…”

“…Moreover, the currently available model from Zefon International contains a series of nylon meshes in the diffusion stage, which contain consequential amounts of titanium (Mines et al, 2016). Recently, the 2.5 L/min NRD diffusion stage material was changed from a series of mesh screens to a polyurethane foam (Mines et al, 2016). The polyurethane foam has lower LOQs for multiple metals (Mines et al, 2016).…”

“…Recently, the 2.5 L/min NRD diffusion stage material was changed from a series of mesh screens to a polyurethane foam (Mines et al, 2016). The polyurethane foam has lower LOQs for multiple metals (Mines et al, 2016). The diffusion stage material change also reduced the sampling time required to obtain enough mass for analysis (Mines et al, 2016).…”