Polybrominated diphenyl ethers (PBDEs) have been widely used to flame-retard products common in homes and the workplace, and subsequently, they have become widely dispersed in the environment. Detailed compositional knowledge of these complex PBDE mixtures is crucial to a fuller understanding of their toxicological potencies and environmental fate due to selective congener biomagnification, degradation, and transport. Utilizing recenttechnical enhancements and newly available commercial standards, we developed a method capable of analyzing a larger suite of mono- through deca-BDEs. We then characterized the congener composition of six common technical flame-retardant mixtures: two penta-BDE products (DE-71 and Bromkal 70-5DE) two octa-BDE products (DE-79 and Bromkal 79-8DE) and two deca-BDE products (Saytex 102E and Bromkal 82-0DE). PBDEs were analyzed by gas chromatography/mass spectrometry (GC/MS). Structural conformations based on fragmentation patterns and molecular ions were established by electron-capture negative ionization (ECNI) and electron ionization (El). Sixty-four commercially available PBDE standards were chromato-graphed on two GC columns (DB-1HT and DB-5HT) and relative retention indexes (RRI) calculated. Thirty-nine PBDEs were identified in these products, 29 at concentrations >0.02% by weight. Of these, 12 previously unreported congeners have been confirmed as commercial mixture components. Four of these congeners were detected >0.02% w/w (BDE-144, -171, -180, and -201) and three (BDE-75, -184, and -194) at <0.02%. Five other congeners (four <0.02% by weight) were tentatively identified based on their molecular ion and ECNI fragmentation in the absence of corresponding analytical standards.