Asbestos mineral analysis by UV Raman and energy-dispersive X-ray spectroscopy

Our plain-English summary of Asbestos mineral analysis by UV Raman and energy-dispersive X-ray spectroscopy, by R. Petry, R. Mastalerz, S. Zahn, et al (Chemphyschem, 2006).

The study

• Authors: R. Petry, R. Mastalerz, S. Zahn, T.G. Mayerhöfer, G. Völksch, L. Viereck-Götte, B. Kreher-Hartmann, L. Holz, M. Lankers, J. Popp
• Journal: Chemphyschem
• Published: 2006;7(2):414-20
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The applicability of a UV micro-Raman setup was assessed for the rapid identification of fibrous asbestos minerals using 257 and 244 nm laser light for excitation. Raman spectra were obtained from six asbestos reference standards belonging to two basic structural groups: the serpentines (chrysotile) and the amphiboles (crocidolite, tremolite, amosite, anthophyllite, and actinolite). The UV Raman spectra reported here for the first time are free from fluorescence, which is especially helpful in assessing the hydroxyl-stretching vibrations. The spectra exhibit sharp bands characteristic of each asbestos species, which can be used for the unambiguous identification of known and unknown asbestos fibres. Evident changes of the relative band intensities sensitively reflect the chemical substitutions that typically occur in asbestos minerals. The elemental composition of the asbestos reference samples was analysed by using a scanning electron microscope equipped with an energy-dispersive X-ray (EDX) spectrometer. The discussion of the experimental results in terms of EDX analysis sheds new light on the structural and vibrational consequences of cation distribution in asbestos minerals.

In plain English

This was a laboratory study of mineral samples, not a study of people or disease. The authors tested whether ultraviolet (UV) Raman spectroscopy, a laser-based technique using 257 and 244 nm laser light, could identify asbestos fibres. Samples came from the mineral collection of the University of Jena, Germany. They included six asbestos reference standards (chrysotile, crocidolite, tremolite, amosite, anthophyllite and actinolite), plus riebeckite and talc. The chemical makeup of the samples was measured with a scanning electron microscope fitted with an energy-dispersive X-ray (EDX) analyser. Both laser wavelengths distinguished chrysotile from the amphiboles and from talc. A band around 532 cm-1 seen in tremolite was absent in talc. No hydroxyl (OH) signals could be obtained from crocidolite; the authors assumed that sodium occupying one specific position (the A site) in its crystal structure suppressed them. Amosite and actinolite gave noisy spectra. The tremolite sample was very close to its ideal composition; the crocidolite sample was not. The authors concluded the method is highly sensitive to chemical variation in asbestos minerals. They noted that band intensity ratios are only semi-quantitative and that one band assignment needs further work.

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 study: UV micro-Raman spectroscopy combined with scanning electron microscopy and energy-dispersive X-ray (SEM/EDX) analysis of mineral reference samples, with repeated measurements on each sample
• Who was studied: Six asbestos reference standards from the serpentine group (chrysotile) and the amphibole group (crocidolite, tremolite, amosite, anthophyllite, actinolite), plus riebeckite and talc, supplied by the Collection of Mineralogy, Department of Geology, University of Jena. The sources listed include Québec, Canada (chrysotile), Oranje River, South Africa (crocidolite) and Penge mine, Transvaal, South Africa (amosite).
• Exposure: Not an exposure study. The samples were analysed by UV Raman spectroscopy with 257 nm and 244 nm laser excitation, and their elemental composition was measured by SEM/EDX.
• Main results:
  • For chrysotile, both excitation wavelengths (257 and 244 nm) were equally suited to telling the serpentines apart from the amphiboles or from structurally related silicates such as talc.
  • For crocidolite, none of the expected OH stretching signals could be obtained with either the 257 nm or the 244 nm laser line.
  • The authors assumed, without establishing it, that sodium entering the A site of the crocidolite structure strongly suppressed the OH stretching signals.
  • In tremolite, a broad band around 532 cm-1 appeared with both 257 and 244 nm excitation. This band was absent in the spectrum of talc, which allowed the two minerals to be told apart.
  • At 244 nm, the amphibole samples other than anthophyllite (amosite and actinolite) gave low signal-to-noise spectra. These spectra also contained sharp bands from nitrogen and oxygen in the laboratory air.
  • By SEM/EDX, the tremolite sample was very close to its ideal chemical composition.
  • By SEM/EDX, the crocidolite sample did not match its ideal chemical composition.
  • By SEM/EDX, the chrysotile sample from the Québec asbestos mine contained traces of calcium, sulphur and manganese.
• The authors' conclusion: The authors concluded that UV micro-Raman spectroscopy is highly sensitive to the structural differences caused by the chemical substitutions typical of asbestos minerals. They also concluded that the observed bands are different enough to tell serpentine and amphibole asbestos species apart.
• Limitations the authors state:
  • The ratios of band intensities can serve only for semi-quantitative analysis and tentative structural assignment.
  • The suggested assignment of the band near 530 cm-1 (to iron substituting for magnesium) is tentative and may need further investigation to verify.

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• Penge mine, Transvaal

All asbestos mines

Topics

Medical terms in this study, explained in our Lexicon: Asbestos, Serpentine Group, Chrysotile, Amphibole Group, Crocidolite, Tremolite, Amosite, Anthophyllite.

Related studies

• Study of inorganic particles, fibers, and asbestos bodies by variable pressure scanning electron microscopy with annexed energy dispersive spectroscopy and micro-Raman spectroscopy in thin sections of lung and pleural plaque — C. Rinaudo, A. Croce, et al. (2010)
• Quantitative characterization of the mesothelioma-inducing erionite series minerals by transmission electron microscopy and energy dispersive spectroscopy — M. Dogan (2012)
• Lung dust content in idiopathic pulmonary fibrosis: a study with scanning electron microscopy and energy dispersive x ray analysis — E. Monsó, J.M. Tura, et al. (1991)
• Application of portable Raman instruments for fast and non-destructive detection of minerals on outcrops — J. Jehlicka, P. Vítek, et al. (2009)
• EPR, optical, infrared and Raman spectral studies of Actinolite mineral — N.O. Gopal, K.V. Narasimhulu, et al. (2004)
• Coupling SEM-EDS and confocal Raman-in-SEM imaging: A new method for identification and 3D morphology of asbestos-like fibers in a mineral matrix — G. Wille, D. Lahondere, et al. (2019)

Browse return to medical research.