Determination of C0 -C9 alkyl phenols in produced-water-exposed fish eggs using gas chromatography/tandem mass spectrometry.

Produced water (PW) discharge from the oil and gas industry represents the largest intentional marine waste volume. Alkyl phenols (APs) are one of the main toxic component groups found in PW, with concentration of APs in discharged PW from the Norwegian Sector of the North Sea up to >16 mg/L. Several species of fish spawn in direct proximity to offshore production platforms and may be at risk of AP exposure. Therefore, a sensitive method to determine the potential for bioaccumulation of APs in fish eggs is needed. Fish eggs were extracted using liquid-solid extraction followed by gel permeation chromatography cleanup. Analysis was performed by gas chromatography coupled to triple quadrupole mass spectrometry. Extraction and analytical conditions were optimized for analysis of phenol and 30 APs (C1 -C9 ) with different degrees of branching in the alkyl chain. The method was verified and applied to analyze the body residue of APs in PW-exposed marine fish (Atlantic cod, Gadus morhua) eggs. A comprehensive and sensitive method for the determination of C0 -C9 APs was developed. Detection limits were in the range 0.03-8 ng. Apart from a few compounds with poor recovery, the method generally provided reliable results with good precision (<15%). We demonstrate the successful application of an optimized extraction method for APs in fish eggs and show first results of AP accumulation in cod embryos exposed to PW in the laboratory.