EPA Method 1668B

This revision of Method 1668 (Method 1668B; the "Method") revises EPA Method 1668A to replace single-lab quality control (QC) acceptance criteria with interlaboratory criteria, and make other changes described below. Method 1668B was developed by the Office of Water’s Office of Science and Technology (OST) for use in Clean Water Act (CWA) programs. Method 1668B is based on the results of an interlaboratory validation study, and a peer review of that study. Method 1668B, and the validation study report, Method1668A Interlaboratory Validation Study Report (EPA-821-08-021), are available at EPA’s CWA methods website at www.epa.gov/waterscience/methods.

Method 1668B determines chlorinated biphenyl congeners in environmental samples by isotope dilution and internal standard high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). The Method was developed for use in wastewater, surface water, soil, sediment, biosolids and tissue matrices. Other applications and matrices may be possible, which may or may not require modifications of sample preparation, chromatography, etc. The detection limits and quantitation levels in this Method are usually dependent on the level of interferences and laboratory background levels rather than instrumental limitations.

The estimated minimum levels of quantitation in Table 2 are concentrations at which a congener can be measured with laboratory contamination present. In water these values range from 10 to 500 parts per quadrillion (picograms per liter, pg/L). A laboratory may establish a lower reporting level for a congener, see Sect. 17.6.1.4.