A Personal Nanoparticle Respiratory Deposition (NRD) Sampler

Abstract

A lightweight (60 g), personal nanoparticle respiratory deposition (NRD) sampler was developed to selectively collect particles smaller than 300 nm similar to their typical deposition in the respiratory tract. The sampler operates at 2.5 Lpm and consists of a respirable cyclone fitted with an impactor and a diffusion stage containing mesh screens. The cut-point diameter of the impactor was determined to be 300 nm with a sharpness σ = 1.53. The diffusion stage screens collect particles with an efficiency that matches the deposition efficiency of particles smaller than 300 nm in the respiratory tract. Impactor separation performance was unaffected by loading at typical workplace levels (p-value = 0.26). With chemical analysis of the diffusion media, the NRD sampler can be used to directly assess exposures to nanoparticles of a specific composition apart from other airborne particles. The pressure drop of the NRD sampler is sufficiently low to permit its operation with conventional, belt-mounted sampling pumps.

Mathematical Description of Experimentally Determined Charge Distributions of a Unipolar Diffusion Charger

“…The best estimate of a worker's exposure can be derived from mobile, ideally personal measurements, taking aerosol samples in the breathing zone of the worker. Personal samplers for nanoparticles, however, are currently all more or less still at a research level (Azong-Wara et al 2009;Furuuchi et al 2010;Cena et al 2011). Due to the lack of suitable personal measurement equipment, extensive measurement campaigns with a large set of bulky equipment are commonly carried out for a detailed assessment of possible exposure.…”

Accurate quantification of tio2nanoparticles collected on air filters using a microwave-assisted acid digestion method

“…However, this device is expensive to build and requires a large air sampling pump to overcome the high pressure drop of the nanoparticle impactor. Cena et al [30] introduced the nanoparticle respiratory dose (NRD) sampler, which uses a respirable cyclone to aspirate particles followed by a 300-nm impactor prior to collection of nanoparticles by diffusion onto nylon mesh screens as they deposit in the human respiratory tract. The NRD is inexpensive (<$30) and offered commercially (ZNRD001, Zefon International, Ocala, FL) but would require modification to use the titanium-free MCE filter for analyzing Ti nanoparticle concentrations.…”

“…The NRD is inexpensive (<$30) and offered commercially (ZNRD001, Zefon International, Ocala, FL) but would require modification to use the titanium-free MCE filter for analyzing Ti nanoparticle concentrations. [23] Future work will investigate the limits of detection for nylon mesh screens and other diffusion substrate for integration into the NRD sampler. Therefore, an alternative protocol has been proposed utilizing the size-selective air sampling combined with the developed microwave-assisted acid digestion for accurate quantification of airborne TiO 2 nanoparticles in Figure 4 in future nanoparticle exposure assessments.…”

“…However, there are new samplers available for appropriate size-selective sampling for fine particles and nanoparticles. [21–23] Second, NIOSH 7300 method requires the use of perchloric acid (HClO 4 ) to digest the filter and collected particles. Given its strong oxidizing properties, hazardous nature and highly regulated status, HClO 4 is commonly avoided in environmental test laboratories.…”

Particle Sampling by TEM Grid Filtration

“…Some are based on the phenomenon of diffusion (Tsai et al 2009;Cena et al 2011), and others on thermophoresis (Lyyränen et al 2009), electrostatic precipitation (Dixkens and Fissan 1999;Fierz et al 2007;Li et al 2010;Miller et al 2010), etc.…”