Risk assessment for phosphate ester flame retardants (PFRs) based on the results of environmental analysis with accurate quantification values have been internationally required. However, it is not easy to accurately determine the concentrations of PFRs in the samples which contain complicated matrices. As the result of international interlaboratory study (ILS) on the analysis of PFRs in environmental and dust samples, ten key points on blank contamination and analytical performance were reported as the technical knowledge related to the quality assurance and quality control (QAQC) for the analysis of PFRs. Additionally, as the results of ILS and the examination of analytical method of PFRs in National Institute Environmental Studies (NIES) laboratory, three key points of technical knowledge on analytical performance which are the isomer-specific quantification of tris(2-chloroisopropyl) phosphate and tris(methyl phenyl) phosphate, the co-injection with polyethylene glycol, and the confirmation of analytical precision using environmental matrices, significantly progressed in QAQC for the analysis of PFRs.