Sampling and Analysis Using Filters

Raynor, Peter; Leith, David; Lee, K. W.; Mukund, R.

doi:10.1002/9781118001684.ch7

Cited by 21 publications

(18 citation statements)

References 74 publications

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“…Following Raynor et al (14) the theoretical collection efficiency by particle diameter ( E T ) of the three selected nonwoven textiles was computed as:

E_{T} = 1 - italicexp (\frac{- 4 E_{F} α L}{π d_{f}})

where E F is the single fiber efficiency, α is the solid volume fraction calculated using equation 1, and d f is the fiber diameter. E F was calculated as:

E_{F} = E_{D} + E_{R}

where E D is the single fiber efficiency due to diffusion and E R is the single fiber efficiency due to interception.…”

Section: Methodsmentioning

confidence: 99%

“…The effects of inertial impaction and gravitational settling were neglected because particles of interest were smaller than 300 nm. The single fiber efficiency E D was calculated as:

E_{D} = 1.6 (\frac{1 - α}{K u}) P e^{- \frac{2}{3}} C c_{(d)}

where Pe is the Peclet number (14) , Ku is the Kuwabara hydrodynamic factor (14) , and C C(d) is the Cunningham slip correction factor calculated as:

C_{C (d)} = 1 + 0.388 K n_{f} {(\frac{(1 - α) P e}{K u})}^{\frac{1}{3}}

In Equation 5, Kn f is the Knutsen number of the nonwoven textile fiber. E R was calculated as:

E_{R} = (\frac{1 + R}{2 K u}) [2 \ln (1 + R) - 1 + α + {(\frac{1}{1 + R})}^{2} (1 - \frac{α}{2}) - (\frac{α}{2}) {(1 - R)}^{2}]

where R is the ratio of the particle diameter to the particle fiber.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Nonwoven textile for use in a nanoparticle respiratory deposition sampler

Vosburgh

Park

Mines

et al. 2017

Journal of Occupational and Environmental Hygiene

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The nanoparticle respiratory deposition (NRD) sampler is a personal sampler that combines a cyclone, impactor, and a nylon mesh diffusion stage to measure a worker’s exposure to nanoparticles. The concentration of titanium in the nylon mesh of the diffusion stage complicates the application of the NRD sampler for assessing exposures to titanium dioxide nanoparticles. This study evaluated commercially available nonwoven textiles for use as an alternative media in the diffusion stage of the NRD sampler. Three textiles were selected as containing little titanium from an initial screening of 11 textiles by field portable x-ray fluorescence (FPXRF). Further evaluation on these three textiles was conducted to determine the concentration of titanium and other metals by inductively coupled plasma – optical emission spectroscopy (ICP-OES), the number of layers required to achieve desired collection characteristics for use as the diffusion stage in the NRD sampler (i.e., the nanoparticulate matter, NPM, criterion), and the pressure drop associated with that number of layers. Only three (two composed of cotton fibers, C1 and C2; and one of viscose bamboo and cotton fibers, BC) of 11 textiles screened had titanium concentrations below the limit of detection the XRF device (0.15 μg/cm2). Multiple metals, including small amounts of titanium, were found in each of the three nonwoven textiles using ICP-OES. The number of 25-mm-diameter layers required to achieve the collection efficiency by size required for the NRD sampler was three for C1 (R2 = 0.95 with reference to the NPM criterion), two for C2 (R2 = 0.79), and three for BC (R2 = 0.87). All measured pressure drops were less than the theoretical and even the greatest pressure drop of 65.4 Pa indicated that a typical personal sampling pump could accommodate any of the three nonwoven textiles in the NRD sampler. The titanium concentration, collection efficiency, and measured pressure drops show there is a potential for nonwoven textiles to be used as the diffusion stage of the NRD sampler.

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“…Following Raynor et al (14) the theoretical collection efficiency by particle diameter ( E T ) of the three selected nonwoven textiles was computed as:

E_{T} = 1 - italicexp (\frac{- 4 E_{F} α L}{π d_{f}})

where E F is the single fiber efficiency, α is the solid volume fraction calculated using equation 1, and d f is the fiber diameter. E F was calculated as:

E_{F} = E_{D} + E_{R}

where E D is the single fiber efficiency due to diffusion and E R is the single fiber efficiency due to interception.…”

Section: Methodsmentioning

confidence: 99%

“…The effects of inertial impaction and gravitational settling were neglected because particles of interest were smaller than 300 nm. The single fiber efficiency E D was calculated as:

E_{D} = 1.6 (\frac{1 - α}{K u}) P e^{- \frac{2}{3}} C c_{(d)}

where Pe is the Peclet number (14) , Ku is the Kuwabara hydrodynamic factor (14) , and C C(d) is the Cunningham slip correction factor calculated as:

C_{C (d)} = 1 + 0.388 K n_{f} {(\frac{(1 - α) P e}{K u})}^{\frac{1}{3}}

In Equation 5, Kn f is the Knutsen number of the nonwoven textile fiber. E R was calculated as:

E_{R} = (\frac{1 + R}{2 K u}) [2 \ln (1 + R) - 1 + α + {(\frac{1}{1 + R})}^{2} (1 - \frac{α}{2}) - (\frac{α}{2}) {(1 - R)}^{2}]

where R is the ratio of the particle diameter to the particle fiber.…”

Section: Methodsmentioning

confidence: 99%

Nonwoven textile for use in a nanoparticle respiratory deposition sampler

Vosburgh

Park

Mines

et al. 2017

Journal of Occupational and Environmental Hygiene

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“…Fibrous filters are composed of a mat of cellulose, glass, quartz, asbestos, or polystyrene fibers in random orientation within the plane of the filter sheet. Membrane-type filters have straight-through or sinuous pores (Raynor et al 2011) and are made of Teflon, polycarbonate, nylon, polyvinyl chloride (PVC), and cellulose esters. Membrane filters have a more limited loading capacity than fiber filters, because most of the deposit is confined to the surface where some may be lost with heavy deposits.…”

Section: Filter Processing Facilitymentioning

confidence: 99%

Filter Processing and Gravimetric Analysis for Suspended Particulate Matter Samples

et al. 2017

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Aerosol sampling onto filter media with laboratory weighing before and after drawing air through the filter is the most commonly applied method to determine PM 2.5 and PM 10 concentrations. Although simple in concept, determining the net gain in weight from an aerosol deposit is complicated by adsorption of gases onto the filter, retention of water by the filter and the deposit, electrostatic charges that result in attraction of the filter to balance surfaces, contamination during filter handling, losses or additions to filter material, evaporation of semivolatile aerosols, and inhomogeneous sample deposits. Additional restrictions apply when the weighed filters are submitted to subsequent chemical speciation analyses. A precisely controlled environment, with clean air and constant temperature and humidity, is required for filter weighing and processing, and filters must be equilibrated at these conditions. Balances must have sensitivities of B1 lg, be calibrated with well-established primary standards, and be regularly serviced. Ionizing sources are used to neutralize electrostatic charges. Regular quality control and quality assurance procedures involve filter inspection for defects before and after sampling, periodic balance zero and span checks, replicate filter weights, and independent system and performance audits.

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“…The number of electrical charges carried by airborne particles, including microorganisms and other airborne biological entities, can considerably modify their deposition in the lung, their collection efficiency on filters and other separation devices, their transport (e.g., deposition in sampling lines) and their behavior during sampling processes (Azhdarzadeh, Olfert, Vehring, & Finlay, 2014;Brockmann, 2011;Liu, Pui, Rubow, & Szymanski, 1985;Raynor, Leith, Lee, & Mukund, 2011;Yao & Mainelis, 2006).…”

Section: Introductionmentioning

confidence: 99%