title: Limitation of fluorescence spectrophotometry in the measurement of naphthenic acids in oil sands process water.
abstract: Fluorescence spectrophotometry has been proposed as a quick screening technique for the measurement of naphthenic acids (NAs). To evaluate the feasibility of this application, the fluorescence emission spectra of NAs extracted from three oil sands process water sources were compared with that of commercial NAs. The NAs resulting from the bitumen extraction process cannot be differentiated because of the similarity of the fluorescence spectra. Separation of the fluorescent species in NAs using high performance liquid chromatography with fluorescence detector proved unsuccessful. The acidic fraction of NAs is fluorescent but the basic fraction of NAs is not fluorescent, implying that aromatic acids in NAs give rise to the fluorescent signals. The concentrations of NAs in oil sands process water were measured by Fourier transform infrared spectroscopy (FTIR), fluorescence spectrophotometry and ultra high performance liquid chromatography-time of flight/mass spectrometry (UPLC-TOF/MS). Commercial Merichem and Kodak NAs are the best standards to use when measuring NAs concentration with FTIR and fluorescence spectrophotometry. In addition, the NAs concentrations measured by fluorescence spectrophotometry are about 30 times higher than those measured by FTIR and UPLC-TOF/MS. The findings in this study underscore the limitation of fluorescence spectrophotometry in the measurement of NAs.
authors: Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta, Canada.
authors: Weibing
authors: W
authors: Lu
authors: Andrea
authors: A
authors: Ewanchuk
authors: Leonidas
authors: L
authors: Perez-Estrada
authors: Dave
authors: D
authors: Sego
authors: Ania
authors: A
authors: Ulrich
mesh_terms: D002264:Carboxylic Acids / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D005453:Fluorescence; D061329:Oil and Gas Fields; D013050:Spectrometry, Fluorescence / Q000379:methods*; D017550:Spectroscopy, Fourier Transform Infrared; D062065:Wastewater / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D002264:Carboxylic Acids; D062065:Wastewater; D014874:Water Pollutants, Chemical; C046170:naphthenic acid