The following are approved microwave ashing method for the EPA and ASTM...
ASTM Methods (American Society of Testing and Materials)
D5630-94 (Standard Test Method for Ash Content in Thermoplastics)
D1506-99 (Standard Test Methods for Carbon Black-Ash Content)
D482-95 (Standard Test Method for Ash from Petroleum Products)
The ASTM methods can be downloaded for a fee at www.astm.org
USP Methods (U.S. Pharmacopeia)
USP 733 (Loss on Ignition)
USP 281 (Residue on Ignition)
The USP methods can be downloaded here.
SEMI (Semiconductor Equipment and Materials International)
Method F48-0600 (Test Method for Determining Trace Metals in Polymer Material)
The SEMI Methods can be downloaded for a fee at www.semi.org/en/Store/Standards/index.htm.
ISO (International Organization for Standardization)
ISO 2171 (Cereals and Milled Cereal Products – Determination of Total Ash)
ISO Methods can be downloaded for a fee at www.iso.org/iso/iso_catalogue.htm.