Identification of Novel Phosphorus-Based Flame Retardants in Curtains Purchased in Japan Using Orbitrap Mass Spectrometry

An analytical method was developed for screening and identifying novel flame retardants in curtains purchased in Japan in 2014 by use of a liquid chromatograph interfaced with a hybrid quadrupole Orbitrap mass spectrometer (LC–Orbitrap-MS; Q Exactive Plus). To enable complete extraction of flame retardants in curtains, we used an extraction method developed earlier, in which a solvent mixture of 1,1,1,3,3,3-hexafluoro-2-propanol/chloroform (1:4, v/v) was used to completely dissolve the curtain matrix. An initial gas chromatography–MS scan analysis confirmed the presence of several unidentified flame retardants in curtains. We then determined the precise masses of the detected compounds by use of a LC–Orbitrap-MS and used that information to construct chemical formula of the detected compounds. The MAGMa online spectral data annotation was then used to generate a list of candidate compounds. For the determination and confirmation of the chemical structures of the candidate compounds, we reviewed the literature and acquired standards and compared mass fragment patterns of the most probable candidate compounds with those of standards. We unequivocally identified the compounds in curtain samples as (5-ethyl-2-methyl-2-oxido-1,3,2-dioxaphosphorinan-5-yl)­methyl-methyl-methylphosphonate (PMMMP), naphthalen-2-yl diphenyl phosphate (NDPhP), and 6-benzyl benzo­[<i>c</i>]­[2,1]­benzoxaphosphinine 6-oxide (BzlDOPO). This study elucidates the occurrence of three novel phosphorus-based flame retardants in curtains, and the technique we proposed here can be applied for the detection of environmental chemicals in other products