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Concentration and Distribution of Naphthenic Acids in the Produced Water from Offshore Norwegian North Sea Oilfields
journal contribution
posted on 2020-02-21, 20:15 authored by Saer Samanipour, Malcolm J. Reid, Jan Thomas Rundberget, Tone K. Frost, Kevin V. ThomasNaphthenic acids
(NAs) constitute one of the toxic components of
the produced water (PW) from offshore oil platforms discharged into
the marine environment. We employed liquid chromatography (LC) coupled
to high-resolution mass spectrometry with electrospray ionization
(ESI) in negative mode for the comprehensive chemical characterization
and quantification of NAs in PW samples from six different Norwegian
offshore oil platforms. In total, we detected 55 unique NA isomer
groups, out of the 181 screened homologous groups, across all tested
samples. The frequency of detected NAs in the samples varied between
14 and 44 isomer groups. Principal component analysis (PCA) indicated
a clear distinction of the PW from the tested platforms based on the
distribution of NAs in these samples. The averaged total concentration
of NAs varied between 6 and 56 mg L–1, among the
tested platforms, whereas the concentrations of the individual NA
isomer groups ranged between 0.2 and 44 mg L–1.
Based on both the distribution and the concentration of NAs in the
samples, the C8H14O2 isomer group
appeared to be a reasonable indicator of the presence and the total
concentration of NAs in the samples with a Pearson correlation coefficient
of 0.89.