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EPA 600/R-93/116
Determination of Asbestos in Bulk Building Materials, July 1993:
EPA 600/R-93/116 is the primary mechanism and a comprehensive method utilized for the determination the asbestos concentration in bulk building materials. Although the method is thought of as only discussing analysis by PLM, other techniques such as TEM are discussed as well. Alternative methods and preparation techniques for the analysis of difficult or low concentration samples is discussed in detail. The PLM method outlines two quantification techniques. The first and simplest is the visual estimate of percent area. A more precise quantification technique employs point counting.
EPA 600/R-93/116 with 400 Point Count
Although Point Counting is more labor intensive, it is less likely to be influenced by bias than visual estimation of percent area. This can be important especially at low asbestos concentrations. Both the accuracy and precision are improved with Point Counting. The more points analyzed the better the accuracy and precision. The 400 point count is used mostly to comply with NESHAP regulations which require that point counting be performed for better precision and accuracy on samples with low concentrations of asbestos.
EPA 600/R-93/116 with 1,000 Point Count
Although Point Counting is more labor intensive, it is less likely to be influenced by bias than visual estimation of percent area. This can be important especially at low asbestos concentrations. Both the accuracy and precision are improved with Point Counting. The more points analyzed the better the accuracy and precision. The 1,000 point count is typically utilized California where the permissible limit for determining if a material is Asbestos Containing is 0.1% asbestos.
Gravimetric Reduction / NOB Preparation
Bulk samples containing dense matrices like floor tiles, mastics and roofing materials are considered in EPA 600/R-93/116 as “Qualitative Problem” samples. If present, asbestos fibers are tightly bound to the matrix material and not easily isolated and detected by microscopy resulting in a false negative. The State of New York defines these types of samples as “NOB” (Non-Friable Organically Bound). An increasing number of states are recognizing the inherent problems with these types of samples. The State of New York has taken the lead in this area and has mandated special preparation procedures be performed prior to analysis. These procedures (NOB Preparation) include gravimetric reduction by ashing the samples several hours in a muffle furnace high temperatures followed by dissolution of the remaining residue with HCl. The final residue is then analyzed by PLM or TEM for the presence of asbestos.
NIOSH 9002
National Institute for Occupational Safety and Health (NIOSH) Method 9002 is a qualitative and semi-quantitative method for the determination of asbestos in bulk samples by PLM. The method measures percent asbestos as perceived by the analyst in comparison to standard area projections, photos, and drawings, or trained experience. The method is not applicable to samples containing large amounts of fine fibers below the resolution of the light microscope.
Amphibole in Vermiculite Insulation - EPA 600/R-04/004
Research Method for Sampling and Analysis of Fibrous Amphibole in Vermiculite Attic Insulation - EPA600/R-04/004
This method provides a procedure for the characterization of the fibrous amphibole content of vermiculite attic insulation. Vermiculite from Zonolite Mountain near Libby, MT is likely to contain fibrous amphibole. Such vermiculite was widely used as an attic insulation or sound dampening material.
NY ELAP - PLM NOB 198.6
Polarized-Light Microscope Method for Identifying and Quantitating Asbestos in Non-Friable Organically Bound Bulk Samples
The New York State method for the analysis of asbestos in Non-Friable Organically Bound (NOB) bulk materials by PLM. Vinyl asbestos tiles have been categorized by NESHAP (1990) as a Category I non-friable asbestos-containing material. VATs present one of the most difficult challenges to laboratories that analyze bulk samples for asbestos. The addition of organic matrix materials, usually vinyl or asphalt compounded the detection problem by coating these small fibers with opaque matter. The Gravimetric Reduction preparation was developed specifically to remove the interfering binders.
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Chatfield / TEM NOB 198.4
Transmission Electron Microscope Method for Identifying and Quantitating Asbestos in Non-Friable Organically Bound Bulk Samples
Similar methods used to determine asbestos content in problematic non-friable organically bound bulk samples. TEM provides the most reliable method for detecting and quantitating these fibers in NOBs. The Gravimetric Reduction preparation was developed specifically to remove the interfering binders. The “residue” is then placed on a carbon coated grid and a visual estimation is made by TEM. The 198.4 method is New York State's TEM method for the analysis of asbestos in Non-friable Organically Bound building materials. It typically follows a visual estimation by PLM analysis as both are required in order to classify a material as a Non Asbestos Containing Material in New York State.
Conventional Quantitative Analysis
This method determines the weight percentage of asbestos in bulk samples by TEM. Length and width dimensions of asbestos fibers are meticulously measured and corresponding weights are calculated based on known densities of asbestos types detected.
Qualitative (+ / -) Analysis
This method is quite simply a quick check for asbestos content in bulk samples. A subsample of a material is ground in a mortar and pestle, sonicated in deionized water and placed on a carbon coated grid. The grid is then analyzed by TEM for the presence of asbestos. NOTE: This method has a tendency for false negatives due to the insufficient sample preparation procedure.
EPA 600/J-93/167 (Asbestos in Carpet)
Methods for the Analysis of Carpet Samples for Asbestos EPA 600/J-93/167
A small piece of carpet (typically 10 by 10 cm) is analyzed by TEM to determine if asbestos fibers are present. Essentially, the carpet sample is sonicated in particle free water to release the fibers and the resulting liquid is filtered and analyzed by TEM. This method has a much greater sensitivity for asbestos than the ASTM D5755 “Microvac” method.
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