The revolution in asbestos analysis

By Luigi Raspolini - November 30, 2018

The detection of asbestos fibers is a complex and time-consuming operation, requiring the use of electron microscopes and highly trained operators. This results in high costs for the analysis and a slow throughput. What if the microscope could support the operator with an automated fiber detection routine and cut the time (and cost) required for each analysis? Find out how in this blog.

Asbestos detection: a time-consuming analysis

Detecting airborne asbestos fibers is a difficult task and several norms are in place to describe which procedures should be implemented for a correct evaluation of the risks. ISO 14966 describes how the inspection must be performed. From the collection of the sample, with special air filtering devices and golden membranes, to the analysis with an electron microscope.

The norms require that - on average - more than 100 images are inspected by a highly-experienced operator. Whenever a fiber is detected, the operator must assess whether it complies with the morphological and compositional parameters specified in the norm such as size, form factor, aspect ratio and chemical composition. Its position in the image must also be assessed to avoid double counting as well as making sure that all the fibers are counted. Finally, the operator must complete a report with the findings and certificate whether the inspected environment is contaminated and represents a risk for the people occupying it.

Asbestos fibers are small, do not produce a lot of contrast when imaged, and it requires a lot of practice and training to be able to spot all the fibers on a sample. Not to mention that it is a very long and tedious operation. You can imagine how the inspection of a set of samples from a potentially hazardous location can easily require hours, depending greatly on the experience of the user.

Speed up your analysis with AsbestoMetric 

With the idea of supporting the operator in mind, a few years ago we started looking for a way to facilitate and speed up the procedure, automating repetitive tasks so that the operator only needs to verify the outcome and certify the accuracy of the results.

The result of this research is a completely automated fibers detection routine. This is based on the combination of a Phenom XL scanning electron microscope (equipped with a BSE detector and a SE detector for imaging, and an EDS detector for chemical composition analysis), a filter holder that can contain up to 9 filters at once, and software that operates the microscope and runs the analysis.

The procedure adheres to the instructions contained in ISO 14966:

  1. The microscope scans the filter surface. Parameters such as the total area to scan can be defined by the user, depending on the sampling procedure.

  2. Every image is processed in search of fibers. The position of the fibers is stored to enable the operator to revisit the position where the fibers were detected.

  3. The detected fibers are measured and classified according to dimension and aspect ratio.

The software then enables the operator to reposition the electron beam on each fiber and eventually start an EDS analysis to verify, via the chemical composition, whether the investigated object is truly asbestos, and define which kind.

4. Once all the fibers have been found and the operator has assessed the accuracy of the results, the software generates a report containing all the findings and relevant information resulting from the analysis.

Run your analysis overnight 

When constructing a solution for such a sensitive task, we kept one word in mind: reliability.

To achieve that, we chose to use a system that can scan for very long time without requiring maintenance and with an electron source that provides a stable signal for as long as possible. The system also needed to be affordable and have a stage large enough to load as many samples as possible – even unattended, during the night.

  • The Phenom XL can load up to 9 filters at the same time.

  • The CeB6 electron source guarantees more than 1500 hours of lifetime.

  • The source does not break at the end of its lifespan, so the analysis can continue and the replacement can be scheduled over the weekend.

  • The system is easy to operate, robust and does not require special tables or floors.

  • Samples are loaded in less than 1 minute.

  • It is an in-house, out of the box solution.

AsbestoMetric: low cost - high throughput 

AsbestoMetric can process 100 images in approximately 40 minutes, which means that in approximately 6 hours the software can analyze 9 filters. Practically speaking, the software can be launched in the morning, the results can be inspected during the day and a second run can be launched overnight – giving the operator time to launch multiple analyses.

The analysis immediately becomes much cheaper and the expertise of the operator is used in a more valuable way, enhancing his engagement and job quality. Furthermore, a higher sample throughput can be achieved, so that more requests can be accepted and processed in time.

As good as human

Looking at thousands of images a day, with all images looking the same, searching for small and barely visible objects is an extremely tiring task and fatigue can affect the quality of the results.

Using an automated procedure guarantees that all fibers are found and measured with extreme accuracy.

If you’d like to know more about how the system can help you boost the laboratory productivity, get in touch. Or download the AsbestoMetric spec sheet at this link.

Download the AsbestoMetric specification sheet

About the author

Luigi Raspolini is an application engineer for the Thermo Scientific Phenom Desktop SEM product range at Thermo Fisher Scientific. Luigi is constantly looking for new approaches to materials characterization, surface roughness measurements, and composition analysis. He is passionate about improving user experiences and demonstrating the best way to image every kind of sample.

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