Identification and quantification of halogenated and non-halogenated octylphenol polyethoxylate residues by gas chromatography/mass spectrometry using electron ionization and chemical ionization

Residues of octylphenol polyethoxylates (OPEO) are frequently found in wastewater effluents. OPEO are commonly used surfactants. The polyethoxy chain of OPEO may be shortened or carboxylated during biological wastewater treatment and the aromatic ring chlorinated or brominated during wastewater disinfection with chlorine. Mass spectral data obtained using electron ionization (EI) and chemical ionization (CI) are presented which positively characterize these residues. For CI, methane was used as the reactant gas and protonated molecular ions were observed. The most prominent ions formed under EI resulted from benzylic cleavage while the prominent ions formed under CI resulted from alkyl ion displacement and olefin displacement. EI and CI mass spectra are summarized and fragmentation mechanisms are proposed. Response factors are presented for quantitative analysis by single ion monitoring.