This article provides a review of the routine methods currently utilized for total naphthenic acid analyses. There is a growing need to develop chemical methods that can selectively distinguish compounds found within industrially derived oil sands process affected waters (OSPW) from those derived from the natural weathering of oil sands deposits. Attention is thus given to the characterization of other OSPW components such as oil sands polar organic compounds, PAHs, and heavy metals along with characterization of chemical additives such as polyacrylamide polymers and trace levels of boron species. Environmental samples discussed cover the following matrices: OSPW containments, on-lease interceptor well systems, on- and off-lease groundwater, and river and lake surface waters. There are diverse ranges of methods available for analyses of total naphthenic acids. However, there is a need for inter-laboratory studies to compare their accuracy and precision for routine analyses. Recent advances in high- and medium-resolution mass spectrometry, concomitant with comprehensive mass spectrometry techniques following multi-dimensional chromatography or ion-mobility separations, have allowed for the speciation of monocarboxylic naphthenic acids along with a wide range of other species including humics. The distributions of oil sands polar organic compounds, particularly the sulphur containing species (i.e., OxS and OxS2) may allow for distinguishing sources of OSPW. The ratios of oxygen- (i.e., Ox) and nitrogen-containing species (i.e., NOx, and N2Ox) are useful for differentiating organic components derived from OSPW from natural components found within receiving waters. Synchronous fluorescence spectroscopy also provides a powerful screening technique capable of quickly detecting the presence of aromatic organic acids contained within oil sands naphthenic acid mixtures. Synchronous fluorescence spectroscopy provides diagnostic profiles for OSPW and potentially impacted groundwater that can be compared against reference groundwater and surface water samples. Novel applications of X-ray absorption near edge spectroscopy (XANES) are emerging for speciation of sulphur-containing species (both organic and inorganic components) as well as industrially derived boron-containing species. There is strong potential for an environmental forensics application of XANES for chemical fingerprinting of weathered sulphur-containing species and industrial additives in OSPW.
Untargeted analysis of a composite house dust sample has been performed as part of a collaborative effort to evaluate the progress in the field of suspect and nontarget screening and build an extensive database of organic indoor environment contaminants. Twenty-one participants reported results that were curated by the organizers of the collaborative trial. In total, nearly 2350 compounds were identified (18%) or tentatively identified (25% at confidence level 2 and 58% at confidence level 3), making the collaborative trial a success. However, a relatively small share (37%) of all compounds were reported by more than one participant, which shows that there is plenty of room for improvement in the field of suspect and nontarget screening. An even a smaller share (5%) of the total number of compounds were detected using both liquid chromatography–mass spectrometry (LC-MS) and gas chromatography–mass spectrometry (GC-MS). Thus, the two MS techniques are highly complementary. Most of the compounds were detected using LC with electrospray ionization (ESI) MS and comprehensive 2D GC (GC×GC) with atmospheric pressure chemical ionization (APCI) and electron ionization (EI), respectively. Collectively, the three techniques accounted for more than 75% of the reported compounds. Glycols, pharmaceuticals, pesticides, and various biogenic compounds dominated among the compounds reported by LC-MS participants, while hydrocarbons, hydrocarbon derivatives, and chlorinated paraffins and chlorinated biphenyls were primarily reported by GC-MS participants. Plastics additives, flavor and fragrances, and personal care products were reported by both LC-MS and GC-MS participants. It was concluded that the use of multiple analytical techniques was required for a comprehensive characterization of house dust contaminants. Further, several recommendations are given for improved suspect and nontarget screening of house dust and other indoor environment samples, including the use of open-source data processing tools. One of the tools allowed provisional identification of almost 500 compounds that had not been reported by participants.
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The online version of this article (10.1007/s00216-019-01615-6) contains supplementary material, which is available to authorized users.
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