Electron impact, electron capture negative ionization and positive chemical ionization mass spectra of organophosphorus flame retardants and plasticizers.

Phosphate esters are important commercial products that have been used both as flame retardants and as plasticizers. To analyze these compounds by gas chromatographic mass spectrometry, it is important to understand the mass spectra of these compounds using various ionization modes. This paper is a systematic overview of the electron impact (EI), electron capture negative ionization (ECNI) and positive chemical ionization (PCI) mass spectra of 13 organophosphate esters. These data are useful for developing and optimizing analytical measurements. The EI spectra of these 13 compounds are dominated by ions such as H4 PO4 (+) , (M - Cl)(+) , (M - CH2 Cl)(+) or (M)(+) depending on specific chemical structures. The ECNI spectra are generally dominated by (M - R)(-) . The PCI spectra are mainly dominated by the protonated molecular ion (M + H)(+) . The branching of the alkyl substituents, the halogenation of the substituents and, for aromatic phosphate esters, ortho alkylation of the ring are all significant factors controlling the details of the fragmentation processes. EI provides the best sensitivity for the quantitative measurement of these compounds, but PCI and ECNI both have considerable qualitative selectivity.