SEDL / STP / STP1342-EB / STP42331S

“Internal Standard Addition” Method for Identifying Asbestos Containing Materials In Bulk Samples Containing Low Levels of Asbestos

Frasca, Peter
President, EMSL Analytical, Inc., Westmont, NJ

Newton, John H.
Laboratory Manager, EMSL Analytical, Inc., Westmont, NJ

De Malo, Robert J.
EMSL Analytical, Inc., Westmont, NJ

Pages: 11    Published: Jan 1999

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Abstract

This study introduces a new method for identifying asbestos containing materials (ACM) containing a low percentage of asbestos (≤ 10%). Currently used Polarized Light Microscopy (PLM) and Transmission Electron Microscopy (TEM) methodologies rely on area ratio estimation to determine asbestos concentrations and have limitations at low asbestos levels.

The “Internal Standard Addition” (ISA) method is designed to reduce this deficiency. Specifically, a small portion of sample is weighed and to it is added an amount of asbestos different in type to that present in the sample and equal in quantity to a “density adjusted 1% by weight”. The asbestos containing material (ACM) determination is made with PLM visual comparison of the two types of asbestos and if necessary, by a modified point counting technique. Compared to the current methods, this new technique yielded a significant increase in precision and accuracy and reduction of false positives and false negatives in the range of 0.25% – 5% asbestos.