Gravimetric reduction is a lab preparation that removes most of a sample's binder or matrix before it is examined for asbestos. The sample is weighed, then heated to burn off organic material and treated with acid to dissolve soluble minerals, and the residue is weighed and analyzed. It is used mainly for floor tile, mastics, roofing and other resin-bound materials.
Origin
EPA included gravimetric procedures in its 1993 bulk-sample method after studies showed that polarized light microscopy alone could miss asbestos in nonfriable, organically bound materials. The approach draws on older ashing and acid-digestion techniques used in mineral analysis.
Significance in Asbestos Context
Vinyl floor tiles, mastics, roofing materials and similar products often contain fine chrysotile fibers wrapped in resin or asphalt, which can hide them from a light microscope. Gravimetric reduction strips away that matrix, concentrating the asbestos and making it easier to see and measure. Labs then analyze the residue by PLM or TEM and calculate the asbestos content as a percentage by weight of the original sample. This matters because a product tested only by direct PLM may be reported as asbestos-free when it was not. Some states, such as New York, require TEM confirmation for these materials when PLM finds no asbestos. In a claim, knowing whether a floor tile or mastic result came from gravimetric preparation helps judge how reliable a negative result is.
Example Sentence
After gravimetric reduction, TEM analysis of the residue showed the floor tile contained about 4 percent chrysotile, although direct PLM had found none.
Related Terms
Low-Temperature Ashing, Acid Digestion, EPA Method 600-R-93-116, Vinyl-Asbestos Tile, Mastic Tile, Transmission Electron Microscopy (TEM), Bulk Sample Analysis
Notes
- If floor tile, mastic or roofing tested negative by PLM alone, ask whether gravimetric preparation or TEM was done.
- Keep samples of old flooring if it can be safely stored; have a professional collect them.
In the research library
2 studies in our medical research library mention Gravimetric Reduction in the title or abstract. Among the most cited:
- Trees as reservoirs for amphibole fibers in Libby, MontanaT.J. Ward, T. Spear, J. Hart, et al, 2006 · The Science of the Total Environment · cited 15 times
- Evidence and reconstruction of airborne asbestos from unconventional environmental samplesJ.S. Webber, M. Getman, T.J. Ward, 2006 · Inhalation Toxicology · cited 3 times
The journals that publish most on it: Inhalation Toxicology (1), The Science of the Total Environment (1).
Category: Analytical & Forensic Methods · All Lexicon terms A–Z
This page is provided for general informational purposes and does not constitute legal advice. Every asbestos case turns on its own facts, exposure history, diagnosis, deadlines, available evidence, and applicable law. Reviewing this page does not create an attorney-client relationship. For advice about your specific situation, call 833-4-ASBESTOS for a free case review.