Estimation of purity of chrysotile asbestos by X-ray diffractometry/Rietveld refinement

Our plain-English summary of Estimation of purity of chrysotile asbestos by X-ray diffractometry/Rietveld refinement, by T. Asahi, T. Matsudaira, S. Kobayashi, et al (Analytical Sciences, 2010).

The study

• Authors: T. Asahi, T. Matsudaira, S. Kobayashi, K. Nakayama, T. Nakamura
• Journal: Analytical Sciences
• Published: 2010;26(12):1295-300
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

X-ray powder diffractometry/Rietveld refinement was employed to estimate the purity of several chrysotile powders for calibrating standards. α-Corundum powder was mixed into each chrysotile sample as an internal standard. X-ray diffractometry was performed on these mixtures, and the mass fractions of amorphous and impurity phase content were calculated using Rietveld refinement. The chrysotile samples had 56.7-92.0% crystalline purity. X-ray diffraction intensities of chrysotile (002) from the samples showed good correlation with the crystalline purity data. In differential thermal analysis results, the exothermal peak intensities were found to be directly proportional to crystalline contents for crystalline purity lower than 80%. Any chrysotile sample can be used as a standard material for quantitative determination upon correction of the crystalline purity, which can be estimated using the proposed method.

In plain English

This laboratory study tested a method for measuring how pure chrysotile asbestos reference materials are. Such materials are used to calibrate X-ray diffraction measurements of asbestos in building materials. The authors examined four chrysotile samples: the Japanese JAWE-111 standard, a commercial chrysotile fiber, the NIST standard SRM1866a, and chrysotile bundles from a mine in Arizona. Two samples were also tested after a hydrochloric acid treatment to remove impurities, giving six samples in all. Each was mixed with corundum (aluminum oxide) and analyzed by X-ray diffraction using a calculation technique called Rietveld refinement. Crystalline purity ranged from 56.7% (the commercial fiber) to 92.0% (the acid-treated JAWE-111 standard). SRM1866a measured 84.5% and the Arizona sample 68.8%. JAWE-111 was stated to be over 95% pure, but the results indicated it contained 13% non-crystalline material. The authors concluded that any chrysotile sample can serve as a standard if results are corrected for its purity, measured with their method. They noted a small error from corundum impurities. They also said refinement settings may affect accuracy, and that the reported purity values include those errors. The study involved no people and no health outcomes.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory analytical chemistry study developing a method (X-ray powder diffractometry with Rietveld refinement and an internal standard) to estimate the crystalline purity of chrysotile calibration materials; no human or animal subjects
• Who was studied: Four chrysotile samples: JAWE-111 chrysotile standard (CHRY-1), commercial chrysotile fiber from WAKO (CHRY-2), NIST SRM1866a (CHRY-3), and pure chrysotile bundles from a mine in Arizona (CHRY-4). CHRY-1 and CHRY-2 were also tested after acid treatment, giving six samples.
• Exposure: Not an exposure study. The material analyzed was chrysotile. Two samples were treated with 0.1 M hydrochloric acid to remove impurities such as brucite, and each sample was mixed with 25.0 mass% corundum as an internal standard.
• Main results:
  • The acid-treated JAWE-111 standard (CHRY-1) had the highest crystalline purity, 92.0%. The commercial chrysotile fiber (CHRY-2) had the lowest, 56.7%.
  • Untreated CHRY-1 had a crystalline purity of 86.7%. Acid treatment raised its crystalline purity by approximately 5%.
  • CHRY-1 was stated to be over 95% pure, but the results indicated it contained 13% non-crystalline phase.
  • The NIST standard SRM1866a (CHRY-3) showed a crystalline purity of 84.5%. The authors stated that quantitation using it as a standard may give values higher than actual by about 15%.
  • The Arizona mine chrysotile (CHRY-4) had an estimated crystalline purity of 68.8% (relative standard deviation 4.8%). The acid-treated commercial fiber had 66.6% (relative standard deviation 4.2%).
  • Relative standard deviations of the purity values ranged from 3.7% to 6.3% over 5 measurements.
  • The diffraction intensity of the chrysotile (002) peak increased linearly with crystalline purity across the six samples.
  • In differential thermal analysis, the exothermal peak intensity was directly proportional to crystalline purity for samples with crystalline purity lower than 80%.
• The authors' conclusion: The authors concluded that all chrysotile samples investigated contained amorphous phases, with crystalline purity below 100%. They concluded that any chrysotile sample can be used as a quantitative standard if corrected for its crystalline purity, estimated with their method.
• Limitations the authors state:
  • The method includes a small error from impurities in the corundum internal standard, which were too small to model by Rietveld refinement.
  • The preferred orientation parameter and the profile and asymmetry parameters used in the refinement may affect accuracy. The reported purity values include errors from these factors.

Topics

Medical terms in this study, explained in our Lexicon: Chrysotile, Crystalline, X-Ray Diffraction (XRD).

Related studies

• Estimation of fibril lengths in chrysotile asbestos fibres — A.W. Atkinson, R.B. Gettins, et al. (1970)
• Updates on exposure estimation for the Québec cohort of chrysotile miners and millers: implications for risk assessment and threshold hypothesis — B.W. Case, A.A. Korchevskiy, et al. (2025)
• Preparation and evaluation of a chrysotile asbestos-containing standard material for validating x-ray diffractometric quantitation — T. Asahi, S. Kobayashi, et al. (2011)
• Estimation of future mortality from pleural malignant mesothelioma in Japan based on an age-cohort model — T. Murayama, K. Takahashi, et al. (2006)
• The burden of cancer at work: estimation as the first step to prevention — L. Rushton, S. Hutchings, et al. (2008)
• Estimation of the past and future burden of mortality from mesothelioma in France — A.G. Ilg, J. Bignon, et al. (1998)

Browse return to medical research.