EBSD Challenges Conventional Asbestos Identification Methods

RJ Lee Group has a long history of providing high-quality asbestos analysis and litigation expertise, supported by the research of our subject matter experts.  Brian Bandli, Ph.D., a Principal Investigator with our materials group, presented a paper (Microscopy & Microanalysis, Vol. 20, pp. 1805-1816) that outlines how electron backscatter diffraction (EBSD) can successfully identify asbestos reference materials and particles of varying morphology for sizes from asbestiform to massive, plus identify minerals from real world samples. 

The ability to correctly identify asbestos particles is critical to protecting public health. This task has become more difficult in recent years.  The challenges posed by newly identified materials and environments where asbestos-like particles may be found require different analytical approaches than have been employed in the past.  However, the tools used in this field have changed little over the last four decades. Recent research employing EBSD for phase identification of amphibole asbestos minerals may help streamline analysis of challenging samples. The purpose of the paper was to determine if EBSD can successfully be used to collect crystallographic information that would be useful for the identification of asbestos fibers.

The first test was to examine reference samples of known asbestos materials. This test indicated that while the quality of diffraction patterns varied among the different asbestos types, most particles analyzed were successfully identified using EBSD. Compositional information was also collected with energy dispersive x-ray spectroscopy (EDS). The second test was to determine if EBSD could measure shape-preferred orientation in samples of varying morphology. Morphology of particles is important because the size and shape of a particle can influence how it behaves in the environment.

The final test examined a real-world sample to determine if particles from a talc ore could be identified. This result was mixed, as some particles were able to produce high quality diffraction patterns. However, many were not. Particularly, the asbestiform particles that had caused specific health concerns could not produce usable patterns.

EDS Spectrum

Figure 1: Energy dispersive x-ray spectroscopy (EDS) spectrum and secondary electron micrograph (inset, cross designates point of analysis) of representative anthophyllite particle from sample TV_plates. b: Transmission electron backscatter diffraction (tEBSD) pattern collected from particle in a. c: tEBSD pattern from b with blue lines showing position of simulated anthophyllite EBSD pattern diffraction bands with orientation of unit cell inset. Blue line on unit cell orientation corresponds to [001], which is parallel to particle elongation.

EBSD has been a powerful tool for phase discrimination since its advent. Accurate phase discrimination for the analysis of asbestos is critically important, as inaccurate results lead to confusion when searching for the source of potentially harmful fibers. The research conducted for this paper determined that using the EBSD and/or transmission electron backscatter diffraction (tEBSD), in conjunction with existing microanalytical platforms used for asbestos fiber testing, demonstrated significant gains in speed and accuracy.

From the editor: This paper is the first published work demonstrating that EBSD can be successfully used for asbestos identification. Dr. Bandli will be receiving an award for this paper from the editors of Microscopy and Microanalysis. The paper, which has been named the “Best Materials Application Paper” was published in Microscopy and Microanalysis in 2014 for research he has done on investigating the utility of EBSD for asbestos analysis.  The award is chosen by the journal editors based on the technical merit and number of downloads of the paper, and represents the significance of this work to the greater microscopy community. To read the whole paper, please click here.

Bryan R. Bandli, Ph.D.

About Bryan R. Bandli, Ph.D.

Bryan Bandli, Ph.D. is a mineralogist and microscopist with over a decade of practical experience performing microanalytical investigations of a wide variety of materials. He has worked extensively on the characterization of asbestos and mineral fibers using scanning electron microscopy, exploring the application of electron backscatter diffraction (EBSD) techniques to the identification of particulate matter and asbestos. His past work includes characterization of amphibole minerals contained in vermiculite from Libby, Montana, and airborne particulates produced from taconite mining operations in Minnesota. He has employed various automated scanning electron microscopy systems to characterize both bulk and particulate materials for mining, geology, and stack emission testing projects. Dr. Bandli’s future plans include exploring the possibility of incorporating EBSD for identification of natural occurrences of asbestos and identification of zeolite particles.

Prior to coming to RJ Lee Group, Dr. Bandli managed an analytical laboratory at the University of Minnesota, Duluth, where he was involved in numerous high-level research projects on a wide range of subjects from biology, ecology, medicine, geology, engineering, and failure analysis. A valuable knowledge resource to both academic and industrial users of the facility, he used his knowledge and experience to apply microscopy and x-ray diffraction techniques to suit their specific needs. In addition to his laboratory work, he taught courses on microscopy and mineralogy to graduate and undergraduate students, and served as a graduate faculty member in the Department of Geological Sciences. Dr. Bandli has produced several peer-reviewed publications and presentations at international conferences.

Contact Bryan Bandli