Toxicity and composition profiles of solid phase extracts of oil sands process-affected water

After fractionation using sequential solid phase extraction, the presence of toxic components in oil sands process-affected water (OSPW) was detected by the Microtox (R) acute toxicity assay using effect-directed analysis. The composition of each fraction was determined by high-resolution electrospray ionization-Orbitrap mass spectrometry. Partial least-squares discriminant analysis (PLS-DA) was used to determine which chemical constituents in all seven fractions co-varied most strongly with toxicity. Although O-2 compounds with double bond equivalence (DBE) between 3 and 9 positively correlated with toxicity, C-15-C-18 O-2-NAs with DBE = 4 (tricyclic structure), as well as C-14-C-17 O-2-NAs with DBE = 3 (bicyclic structure), were found to be most likely associated with OSPW toxicity, consistent with published toxicity studies of surrogate NAS. O-4, many O-3 (i.e. possibly hydroxylated O-2 c-NM) and a few O-2 compounds were found to negatively correlate with toxicity. The results demonstrate the utility of the fractionation and the PLS-DA approach for evaluating composition-response relationships in a complex mixture and also contribute to a better understanding of the toxic compounds in OSPW. These findings will help to focus study on the most environmentally significant components in OSPW. (C) 2015 Elsevier B.V. All rights reserved.