The Office of Science and Technology (OST) in EPAs Office of Water developed Method 1614A for use in Clean Water Act (CWA) programs. EPA is publishing this method for users who wish to measure polybrominated diphenyl ethers (PBDEs), and in 2010, EPA expects to publish a proposal in the Federal Register for public comment to add this method to other CWA methods published at 40 CFR Part 136. EPA Method 1614A was developed to determine polybrominated diphenyl ether (PBDE) congeners in aqueous, solid, tissue, and multi-phase matrices. These ethers are used as flame retardants. The method uses isotope dilution and internal standard high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). This revision of Method 1614 resulted from comments received in a peer review conducted in September of 2007 and changes to the GC temperature program for the short column in Section 10.1.