Isomer-specific determination of 4-nonylphenols using comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry

Abstract

Technical nonylphenol (tNP), used for industrial production of nonylphenol polyethoxylate surfactants, is a complex mixture of C3-10-phenols. The major components, 4-nonylphenols, are weak endocrine disruptors whose estrogenicities vary according to the structure of the branched nonyl group. Thus, accurate risk assessment requires isomer-specific determination of 4-NPs. Comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/ ToFMS) was used to characterize tNP samples obtained from seven commercial suppliers. Under optimal chromatographic conditions, 153-204 alkylphenol peaks, 59-66 of which were identified as 4-NPs, were detected. The 4-NPs comprised ∼86-94% of tNP, with 2-NPs and decylphenols making up∼2-9%and∼2-5%, respectively. The tNP products were analyzed for eight synthetic 4-NP isomers, and results were compared with published data based on GC/ MS analysis. Significant differences were found among the products and between two samples from a single supplier. The enhanced resolution of GC x GC coupled with fast mass spectral data acquisition by ToFMS facilitated identification of all major 4-NP isomers and a number of previously unrecognized components. Analysis of tNP altered by the bacterium, Sphingobium xenophagum Bayram, revealed several persistent 4-NPs whose structures and estrogenicities are presently unknown. The potential of this technology for isomer-specific determination of 4-NP isomers in environmental matrices is demonstrated using samples of wastewatercontaminated groundwater and municipal wastewater. © 2009 American Chemical Society.