Information on the most common EPA recommended analytical methods for asbestos bulk analysis is listed below:

1. PLM BULK - EPA 600


2. PLM POINT COUNT - EPA 600


3. PLM GRAVIMETRIC REDUCTION / POINT COUNT - EPA 600


4. TEM BULK - MODIFIED CHATFIELD

1. PLM BULK - EPA 600

This method is the widely utilized for standard analysis of bulk materials for asbestos content. The analyst first pulverizes the sample and prepares microscope slides of bulk materials. Using a polarized light microscope (PLM), the analyst then tests optical properties of the samples' components, giving both the asbestos types and estimated percentages in the sample material.

Advantages:

• Most commonly used EPA method.
• Most cost effective method.
• Short turn-around-time.

Disadvantages:

• Analysts can not resolve fibers <0.25 micrometers in width.
• Not reliable for some nonfriable materials (ie; floor tile).

2. PLM POINT COUNT - EPA 600

This method uses polarized light microscopy (PLM) to determine the type of asbestos present. The percentage asbestos is quantified by selecting random fields under the microscope and counting points under which any sample material may fall on grids. The percent asbestos is derived by calculating the percentage of asbestos points out of the 400 to 1000 fields counted.

Advantages:

• EPA recommended method for evaluating low percentages of asbestos ( ie. < 10%).
• Test results accepted by EPA over standard PLM analysis.
• Excellent method for friable materials.

Disadvantages:

• Not reliable for some non-friable materials ( ie. floor tiles ).
• Analysts can not resolve fibers < 0.25 micrometers in width.
• Not a percentage by weight.

3. PLM GRAVIMETRIC REDUCTION / POINT COUNT - EPA 600

This method involves removal of the organic and acid-soluble sample matrixes in order to create a concentrated residue .The analyst then tests the residue for the presence of asbestos by polarized light microscopy (PLM). Test results are a derived from the weight of asbestos fibers in the residue, and can be estimated, or point counted.

Advantages:

• Most accurate PLM test method.
• EPA recommended for low concentrations of asbestos.
• Cost effective compared to TEM.

Disadvantages:

• Not reliable for some granular materials (ie. plaster and concrete)

4. TEM BULK - MODIFIED CHATFIELD

Asbestos analysis is performed using high resolution transmission electron microscopy (TEM). Samples are prepared by gravimetric reduction. Test results are derived from the weight of asbestos fibers in the residue.

Advantages:

• High resolution allows very small fibers to be observed (< 0.25 micrometers in width)
• EPA recommended method for low-level concentrations of asbestos.
• Method utilizes chemistry to confirm the presence or absence of asbestos.

Disadvantages:

• Not preferred method for some silicate sample types ( ie. base coat plaster, concrete, etc.).