Technical Exchange: Silica Method Modifications for Improved Interlaboratory Precision

Eller, P.; Key-Schwartz, Rosa; Song, Runrun; Edwards, Stephanie; Schlecht, Paul C.

doi:10.3320/1.2928291

Cited by 13 publications

(20 citation statements)

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“…Although laboratory performance has improved over the last couple of decades due to improvements in analytical methodology and PAT sample preparation (Madsen et al, 1995), variation in the overall analytical performance continues to exceed that of other analytes. For example, PAT rounds 130-133 for crystalline silica showed higher relative standard deviations (RSDs) (16-33% RSD) than for metals (<7% RSD in cadmium, zinc, and lead; Feng and Schlecht, 2000;Grunder and Bell, 2000;Grunder, 2001) and organic solvents (<10% RSD for four analytes; Shulman et al, 1996), and it was attributed to the differences in the standard reference materials and calibration methods between the laboratories (Eller et al, 1999b). In another set of rounds , the RSDs were between 20 and 45% and varied inversely with sampling loading, i.e.…”

Section: Introductionmentioning

confidence: 99%

Quartz Measurement in Coal Dust with High-Flow Rate Samplers: Laboratory Study

Lee

Kim

et al. 2011

The Annals of Occupational Hygiene

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A laboratory study was performed to measure quartz in coal dust using high-flow rate samplers (CIP10-R, GK2.69 cyclone, and FSP10 cyclone) and low-flow rate samplers [10-mm nylon and Higgins-Dewell type (BGI4L) cyclones] and to determine whether an increased mass collection from high-flow rate samplers would affect the subsequent quartz measurement by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analytical procedures. Two different sizes of coal dusts, mass median aerodynamic diameter 4.48 μm (Coal Dust A) and 2.33 μm (Coal Dust B), were aerosolized in a calm air chamber. The mass of coal dust collected by the samplers was measured gravimetrically, while the mass of quartz collected by the samplers was determined by FTIR (NIOSH Manual of Analytical Method 7603) and XRD (NIOSH Manual of Analytical Method 7500) after one of two different indirect preparations. Comparisons between high-flow rate samplers and low-flow rate samplers were made by calculating mass concentration ratios of coal dusts, net mass ratios of coal dusts, and quartz net mass. Mass concentrations of coal dust from the FSP10 cyclone were significantly higher than those from other samplers and mass concentrations of coal dust from 10-mm nylon cyclone were significantly lower than those from other samplers, while the CIP10-R, GK2.69, and BGI4L samplers did not show significant difference in the comparison of mass concentration of coal dusts. The BGI4L cyclone showed larger mass concentration of ~9% compared to the 10-mm nylon cyclone. All cyclones provided dust mass concentrations that can be used in complying with the International Standard Organization standard for the determination of respirable dust concentration. The amount of coal dust collected from the high-flow rate samplers was found to be higher with a factor of 2-8 compared to the low-flow rate samplers but not in direct proportion of increased flow rates. The high-flow rate samplers collected more quartz compared to low-flow rate samplers in the range of 2-10. There was no significant difference between the per cent (%) quartz in coal dust between the * Author to whom correspondence should be addressed. Tel: +1-304-285-5783; fax: +1-304-285-6041; fwc8@cdc.gov. Disclaimer-The findings and conclusions in this report are those of the author(s) and do not necessarily represent the official position of the Centers for Disease Control and Prevention/the Agency for Toxic Substances and Disease Registry. Reference to the ACGIH TLV does not constitute endorsement by the US federal government. FTIR and XRD analyses. The findings of this study indicated that the increased mass of quartz collected with high-flow rate samplers would provide precise analytical results (i.e. significantly above the limit of detection and/or limit of quantification) compared to the mass collected with low-flow rate samplers, especially in environments with low concentrations of quartz or where short sampling times are desired. HHS Public Access

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Section: Introductionmentioning

confidence: 99%

Quartz Measurement in Coal Dust with High-Flow Rate Samplers: Laboratory Study

Lee

Kim

et al. 2011

The Annals of Occupational Hygiene

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“…The colorimetric analytical method exhibits a nonlinear dependence on the mass of crystalline silica present [Eller et al 1999a]. The linear range of the method is limited, and the blank values for samples can be high (20 mg silica or higher) [Talvitie 1951[Talvitie , 1964Talvitie and Hyslop 1958].…”

Section: Colorimetric Spectrophotometrymentioning

confidence: 99%

“…The sensitivity of IR analyses decreases with increasing particle size. The colorimetric method requires the use of a precisely timed heating step with phosphoric acid to digest amorphous silica and silicates during sample preparation, causing a possible loss of some small crystalline silica particles [Eller et al 1999a]. Since particle size affects the sensitivity of all three analytical techniques, the particle size distribution of the calibration standard should closely match the size of the particles retained on the collected sample.…”

Section: Factorsmentioning

confidence: 99%

“…Specifically, appropriate calibration of the technique has been shown to be critical in the accurate measurement of crystalline silica [Eller et al 1999b]. Also, it is essential that only standard reference materials from the National Institute of Standards and Technology (NIST) (for which particle size and phase purity has been established) be used to prepare calibration curves for quartz (1878a) and cristobalite (1879a) [Eller et al 1999a]. No standard reference material for tridymite is available, since this silica polymorph rarely exists in the workplace.…”

Section: Factorsmentioning

confidence: 99%

“…The colorimetric method cannot distinguish between silica and silicates, since it is based on the measurement of silicon. [Eller et al 1999a]. …”

Section: Colorimetric Spectrophotometrymentioning

confidence: 99%

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