Potential of capillary electrophoresis mass spectrometry for the characterization and monitoring of amine-derivatized naphthenic acids from oil sands process-affected water

Capillary electrophoresis coupled to mass spectrometry (CE-MS) was used for the analysis of naphthenic acid fraction compounds (NAFCs) of oil sands process-affected water (OSPW). A standardmixture of amine-derivatized naphthenic acids is injected directly onto the CE column and analyzed by CE-MS in less than 15 min. Time of flight MS analysis (TOFMS), optimized for high molecular weight ions, showed NAFCs between 250 and 800 m/z. With a quadrupole mass analyzer, only low-molecular weight NAFCs (between 100 and 450 m/z) are visible under our experimental conditions. Derivatization of NAFCs consisted of two-step amidation reactions mediated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), ormediated by amixture of EDC and N-hydroxysuccinimide, in dimethyl sulfoxide, dichloromethane or ethyl acetate. The optimum background electrolyte composition was determined to be 30% (V/V) methanol in water and 2% (V/V) formic acid. NAFCs extracted from OSPW in the Athabasca oil sands region were used to demonstrate the feasibility of CE-MS for the analysis of NAFCs in environmental samples, showing that the labeled naphthenic acids are in the mass range of 350 to 1500 m/z. (C) 2016 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.