CEI LABS, Inc.
Laboratory Excellence Since 1987

Asbestos Department

Analytical Methods

Information on the most common analytical methods for asbestos analysis are listed below:

  1. PLM BULK – EPA 600 METHOD
  2. PLM POINT COUNT (400) – EPA 600 METHOD
  3. PLM GRAVIMETRIC – EPA 600 METHOD
  4. TEM BULK – CHATFIELD
  5. TEM AIR – AHERA
  6. TEM AIR – NIOSH 7402
  7. TEM DUST – ASTM METHODS
  8. PCM AIR – NIOSH 7400 METHOD

1. PLM BULK – EPA 600 METHODMenu

This method is commonly used for identification of asbestos in bulk building materials. Samples are examined using a stereoscope, pulverized, and suspect fibers mounted on slide in refractive index liquids. The slide is analyzed by PLM at 100x to 400x magnification to evaluate the optical properties of fibrous and non-fibrous components. The asbestos type is identified based on unique optical properties and the asbestos is quantified by calibrated visual estimation. Laboratory results are reported in percentages (%) for each type of identified asbestos.

Advantages:

  • Most common and cost effective method
  • Fast turn around time

Disadvantages:

  • Analyst can not resolve fibers < 0.25 μm in width
  • Not reliable for some non-friable materials (ie. floor tiles)

2. PLM POINT COUNT (400) – EPA 600 METHODMenu

This method is more accurate than standard PLM and recommended for “friable” building materials. The asbestos type is first determined by standard PLM methods. Then the sample is pulverized and suspect fibers mounted on 8 slides with 50 grid points each for a total of 400 points. The slides are then analyzed by PLM at 100x to 400x magnification and asbestos fibers are counted at the 400 grid points. Laboratory results are reported in percentages (%) for each type of identified asbestos.

Advantages:

  • More accurate method than standard PLM
  • EPA recommended for evaluating < 10% asbestos
  • Excellent method for friable materials

Disadvantages:

  • Analyst cannot resolve fibers < 0.25 micrometers in width
  • Not reliable for non-friable materials
  • Not reliable for VCT’s

3. PLM GRAVIMETRIC – EPA 600 METHODMenu

This method is more accurate than standard PLM and is recommended for most non-friable materials. The asbestos type is first determined by standard PLM methods. Then the sample is weighed, placed in a furnace to burn off organic compounds, and treated with hydrochloric acid to dissolve soluble compounds. The final concentrated residue is mounted on a series of 8 slides and analyzed using PLM Point Count methods. Laboratory results are reported in percentages (%) for each type of identified asbestos.

Advantages:

  • More accurate method than standard PLM
  • EPA recommended for < 10% asbestos
  • Excellent for most non-friable materials

Disadvantages:

  • Analysts can not resolve fibers < 0.25 micrometers in width
  • Not reliable for some granular materials (plasters, concrete)
  • Not reliable for VCT’s

4. TEM BULK – CHATFIELDMenu

The most accurate method for many non-friable materials, and all VCT’s. Samples are prepared using gravimetric reduction, the concentrated residue is diluted with distilled water and agitated to ensure an even distribution of suspended fibers. A drop of the liquid sample is mounted on a specialized grid and analyzed by TEM at 20,000x magnification. The asbestos type and percentage is based on a calibrated visual estimate. Laboratory results are reported as percentages for each type of asbestos identified.

Advantages:

  • High resolution identifies very fine fibers (ie. < 0.25 μm width)
  • More accurate than PLM
  • EPA recommended method for VCT’s
  • Excellent method for many nonfriable materials

Disadvantage:

  • Less reliable for some granular materials (ie. plasters and concrete)

5. TEM AIR – AHERAMenu

The most accurate method for identifying airborne asbestos. Sample filters are mounted on a slide, dissolved using an acetone vaporizer, and placed in a plasma asher to burn the filter. The remaining filter residue is then carbon coated, placed in an acetone bath, and transferred to a copper grid for TEM analysis at 20,000x magnification. The asbestos type is determined based on chemistry and diffraction patterns; quantification is based on the number of asbestos structures, sample volume, and grid square size. Laboratory results are reported as asbestos structures per cubic centimeter (cc3) of sample volume, and structures per square millimeter (mm2) of filter area.

Advantages:

  • More accurate method than PCM
  • Identifies and quantifies asbestos fibers
  • Provides the most legally defensible data

Disadvantage:

  • More expensive than PCM

6. TEM AIR – NIOSH 7402Menu

This method is more accurate than PCM and identifies airborne fiber types and quantities. Sample preparation is similar to TEM AHERA; however, cassette filters are not burned in a plasma asher, and filter residue is analyzed by TEM at 10,000x magnification. The asbestos type is determined based on chemistry and diffraction patterns; asbestos fiber counts are derived based on the number of fibers, sample volume, and grid square size. Laboratory results are reported as asbestos structures per cubic centimeter (cc3) of air.

Advantages:

  • More accurate method than PCM
  • Identifies and quantifies asbestos fibers
  • Excellent method to confirm PCM results

Disadvantages:

  • More expensive than PCM

7. TEM DUST – ASTM METHODSMenu

This method is used to determine if an area has been contaminated with asbestos fibers by evaluating residual dust. The filter is removed the sampling cassette, the cassette is then rinsed with distilled water, diluted to a 100 ml volume, and agitated to ensure even fiber distribution. A 10 ml portion is extracted for analysis and filtered thru a 0.20 micron MCE filter to remove any debris. The preparation and analysis of the MCE filter is the same as described for TEM AHERA. Laboratory results are reported as asbestos structures per square centimeter (cm2) of surface area sampled

Interpreting Test Results:

  • 1,000 to 10,000 structures = low
  • 10,000 to 100,000 structures = moderate
  • 100,000 to 1,000,000 structures = high

Advantages:

  • Inexpensive test method
  • Analyst can identify very small asbestos fibers ( ie. < 0.25 micrometers in width)

Disadvantages:

  • No Federal regulatory standards
  • Longer turn around times than PLM

8. PCM AIR – NIOSH 7400 METHODMenu

This method is often used for EPA final air clearance testing and OSHA contractor personal samples. Filters are mounted on a slide, dissolved using a vaporized acetone and triacetin, analyzed by PCM microscope. Fibers are counted at 100 points with the aid of a Walton Becket graticule. Laboratory results are reported as the number of fibers per cubic centimeter (cc3) of sample volume.

Advantages:

  • Inexpensive test method
  • Fast turn around time

Disadvantages:

  • Analysts can not identify fiber types ( ie. all fibers counted)
  • Fibers < 5 μm in length cannot be resolved