The Environmental Protection Agency adopted amendments to its regulations governing the accreditation of environmental laboratories. The amendments incorporate by reference Method 1633,"Analysis of Per- and Polyfluoroalkyl Substances (PFAS) in Aqueous, Solid, Biosolids, and Tissue Samples by LC-MS/MS,” of EPA’s PFAS Drinking Water Laboratory Methods. See https://www.ilsos.gov/departments/index/register/volume48/register_volume48_14.pdf (pp. 5271-78).