Four new difluorinated tetra-and pentabromo BDE internal standards for GC–MS/GC–ECD analysis,,, and, have been prepared in 98–99.0% purity, mainly by coupling of the new tribromodifluorophenols () and symmetrical bromodiphenyliodonium salts (,). The four difluorinated BDEs showed promising properties as internal standards for quantitative BDE analysis. Tetra-, penta-, hexa-and hepta-brominated BDE reference standards,,, and, were ...