A Novel Method Using Polyurethane Foam (PUF) Substrates to Determine Trace Element Concentrations in Size-Segregated Atmospheric Particulate Matter on Short Time Scales

Abstract

A PUF-ICP-MS method has been developed that can quantify a large number of elements in size-resolved ambient aerosol samples collected over short-time intervals (four hours in this study). The pre-cleaning and digestion protocols developed enabled the quantification of 29 elements (including Hg) in ambient PM sampled onto a PUF substrate. The microwave-assisted acid digestion method affects a total dissolution of both aerosol and substrate, producing a colorless solution with no trace of aerosol, PUF, or polypropylene particulates, and is compatible with many analytical techniques (e.g., ICP-MS, CVAF, GFAA). For the large majority of elements the PUF-ICP-MS method provides superior elemental detection capabilities than traditional XRF approaches and importantly, method detection limits (MDLs) for most studied elements are lower than achieved with a 4-hour MOUDI approach using optimized ICP-MS analysis. For example, MDLs for V, Sr, Cd, Sb, and Hg are respectively 0.15, 0.18, 0.034, 0.051, and 0.0055 (solvent cleaning only for Hg) ng m −3 . Only one-third, or less, of the PUF substrate is required for the ICP-MS analysis leaving the majority of the substrate available for additional characterization, e.g., organic speciation, of the same air mass. A demonstration study conducted in Phoenix, Arizona, shows that this new method can quantitatively resolve differences in element concentrations on short time scales and has the potential to be a powerful new tool for identifying sources of trace and ultra-trace elements. The highly size and time resolved data can also provide useful information for the study of health effects of individual or groups of elements.

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

“…The foam was found to have sufficiently low metals content for occupational exposure assessment of all metals tested, except for Cd (Table 1). The observation that the foam contains Cd is consistent with Dillner et al (2007). The Ti content of the foam was substantially lower than that of the nylon meshes, resulting in a LOD for foam 0.4% that of the nylon meshes.…”

“…Using a newly improved model for deposition of particulate matter in porous foams (Clark et al, 2009), Koehler et al (2009) developed an aerosol sampler using a porous polyurethane foam substrate with an efficiency matching the human respiratory deposition for inhalable particles. Moreover, Dillner et al (2007) demonstrated the ability to digest, analyze, and detect low levels of multiple metals collected on polyurethane foam substrates using elemental analysis. Similar to nylon mesh, the initial and long-term behavior of foam when used to sample chain agglomerate aerosols has not been studied.…”

Cytotoxic and inflammatory potential of size-fractionated particulate matter collected repeatedly within a small urban area

“…All samples were digested in a closed vessel microwave assisted reaction system (MARS 5, CEM Corporation, Matthews, NC) using 100 mL Teflon liners (XP-1500, CEM Corporation, Matthews, NC). Samples and substrates were dissolved as previously described [ 46 ]. After digestion, all samples were evaporated to near dryness in the presence of concentrated HCl [ 47 ] and diluted to 15 mL with 2 % ( v/v ) HCl prior to ICP–MS analysis.…”

Estimation of the Human Extrathoracic Deposition Fraction of Inhaled Particles Using a Polyurethane Foam Collection Substrate in an IOM Sampler

“…, hazardous metals) is also of interest to both demonstrate generalizability of this sampler, as well as to document suitability for consideration of use in a wider array of workplaces. Recent methods for digestion and analysis of PUF using inductively-coupled plasma-mass spectroscopy (ICP-MS) [ 32 ] could be useful in this respect. An additional consideration for the development of an air sampler, especially one that should be deployable to field sites, is the ease of use and robustness ( i.e.…”