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This work reports the monitoring and assessment of naphthenic acids (NAs) in oil sands process-affected water (OSPW), Pleistocene channel aquifer groundwater (PLCA), and oil sands basal aquifer groundwater (OSBA) from an active oil sands development in Alberta, Canada, using ultra performance liquid chromatography time-of-flight mass spectrometry (UPLC-TOF-MS) analysis with internal standard (ISTD) and external standard (ESTD) calibration methods and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) for compositional analysis. PLCA was collected at 45–51 m depth and OSBA was collected at 67–144 m depth. Results of O x −NA concentrations follow an order as OSPW > OSBA > PLCA, indicating that occurrences of NAs in OSBA were likely related to natural bitumen deposits instead of OSPW. Liquid-liquid extraction (LLE) was applied to avoid the matrix effect for the ESTD method. Reduced LLE efficiency accounted for the divergence of the ISTD and ESTD calibrated results for oxidized NAs. Principle component analysis results of O 2 and O 4 species could be employed for differentiation of water types, while classical NAs with C13−15 and Z (-4)−(-6) and aromatic O 2 −NAs with C16−18 and Z (-14)−(-16) could be measured as marker compounds to characterize water sources and potential temporal variations of samples, respectively. FTICR-MS results revealed that compositions of NA species varied greatly among OSPW, PLCA, and OSBA, because of NA transfer and transformation processes. This work contributed to the understanding of the concentration and composition of NAs in various types of water, and provided a useful combination of analytical and statistical tools for monitoring studies, in support of future safe discharge of treated OSPW. [ABSTRACT FROM AUTHOR]

Ultra-performance liquid chromatography ion mobility time-of-flight mass spectrometry (UPLC-IM-TOFMS) was utilized for the analysis of naphthenic acids (NAs) in fractions of pH-dependent sequential liquid-liquid extractions from oil sands process-affected water. Ion-mobility separation technique allowed the differentiation of O y S−NAs (2 ≤ y ≤ 4) from O x −NAs (2 ≤ x ≤ 5) via drift time versus retention time separations. The results indicated that the addition of S atom to the O 2 −NA molecule led to a lower increase in the dissociation constant (pK a ) compared to that caused by the addition of O atom. Because additional O is present as OH while the S atom is present as the C S C structure, the latter does not involve into the deprotonation process directly. The pK a value decreased along with increasing carbon number and |Z| number for O 2 −, O 3 −, O 4 −, and O 2 S−NA species, except for O 5 −, O 3 S−, and O 4 S−NA species, each of which are comprised of chemical structures with distinct functional groups. A calculation model was developed to estimate pK a values for individual and total NA species via nonlinear regression curve fitting, utilizing the relative abundances of detected NA species. pK a values were calculated as 3.9 for total NAs, 3.3 for O 2 −NAs, 4.4 for O 3 −NAs, 7.3 for O 4 −NAs, and 4.1 for O 2 S−NAs. Knowledge of NAs pK a is crucially important for the comprehensive understanding of their potential transformation route and toxicity as well as for the development of water remediation applications. Both the ion-mobility separation technique and the new calculation model could be widely applied for the investigation of other complicated pollutants present in water and wastewater. [ABSTRACT FROM AUTHOR]

This work investigated the oxidative transformation of the organic species in oil sands process-affected water (OSPW) using Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and ultra-performance liquid chromatography time-of-flight mass spectrometry (UPLC-TOF-MS) in both negative and positive electrospray ionization (ESI) modes. This is the first time to apply FTICR-MS to investigate species transformation in OSPW treatments by ferrate (VI), UV/H 2 O 2 , and molecular ozone, and also this is the first preliminary study to use positive ESI to investigate organic species in addition to naphthenic acids (NAs) in these treatment processes. The oxidation processes with potassium ferrate (VI), UV/H 2 O 2 , and ozone transformed the distribution profiles of O x , O x S y , and O x N y organic fractions (i.e., species containing oxygen, sulfur, and nitrogen, with x, y specifying the oxygen number and sulfur/nitrogen number, respectively), with O x S y distribution profiles showing the most sensitive responses to the oxidation extent and can be used as a signature fraction to evaluate the oxidation effectiveness. Negative mode UPLC-TOF-MS confirmed the transformation pattern of O x species observed with FTICR-MS, but positive mode UPLC-TOF-MS results showed severe discrepancies with FTICR-MS results and should be subjected for future further investigation, regarding the relatively low mass resolution of UPLC-TOF-MS. The investigation of the transformation patterns of different organic species using two ionization modes was a preliminary study to enhance the understanding of the efficiency, selectivity, and mechanism of different oxidation processes in OSPW remediation for both NAs and non-NA species. [ABSTRACT FROM AUTHOR]

The fractionation of oil sands process-affected water (OSPW) via pH-dependent extractions was performed to quantitatively investigate naphthenic acids (NAs, C n H 2 n + Z O 2 ) and oxidized NAs (O x -NAs) species (C n H 2 n + Z O 3 and C n H 2 n + Z O 4 ) using ultra-performance liquid chromatography time-of-flight mass spectrometry (UPLC-TOFMS). A mathematical model was also developed to estimate the dissociation constant p K a for NAs species, considering the liquid–liquid extraction process and the aqueous layer acid-base equilibrium. This model provides estimated dissociation constants for compounds in water samples based on fractionation extraction and relative quantification. Overall, the sum of O 2 -, O 3 -, and O 4 -NAs species accounted for 33.6% of total extracted organic matter. Accumulative extracted masses at different pHs revealed that every oxygen atom added to NAs increases the p K a (i.e., O 2 -NAs < O 3 -NAs < O 4 -NAs), indicating that the additional O atoms exist as –OH in O 3 - and O 4 -NAs. Molecule electron-withdrawing groups such as double bonds and aromatic groups, as indicated by higher carbon and − Z number, may be responsible for the lower p K a of O 2 -, O 3 -, and O 4 -NAs. The model obtained estimated p K a values of 3.5 for O 2 -NAs, 4.8 for O 3 -NAs, and 6.8 for O 4 -NAs via nonlinear regression curve fittings. These p K a values are valuable physicochemical parameters for environmental engineering applications targeting OSPW NAs treatment. [ABSTRACT FROM AUTHOR]

Abstract: Influence of laser wavelength, laser irradiance and the buffer gas pressure were studied in high irradiance laser ablation and ionization source coupled with an orthogonal time-of-flight mass spectrometer. Collisional cooling effects of energetic plasma ions were proved to vary significantly with the elemental mass number. Effective dissociation of interferential polyatomic ions in the ion source, resulting from collision and from high laser irradiance, was verified. Investigation of relative sensitivity coefficients (RSC) of different elements performed on a steel standard GBW01396, which was ablated at 1064 nm, 532 nm, 355 nm, and 266 nm, has demonstrated that the thermal ablation mechanism could play a critical role with the first three wavelengths, while 266 nm induces non-thermal ablation principally. Experimental results also indicated that there is no evident discrepancy for most metal elements on RSCs and LODs among four wavelengths at high irradiance, except that high boiling point elements like Nb, Mo, and W have higher RSCs at higher irradiance regions of 1064 nm, 532 nm, and 355 nm due to thermal ablation. A geological standard and a garnet stone were also used in the experiment subsequently, and their RSCs and LODs for metal elements show nonsignificant dependence on wavelength at designated irradiances. All results reveal that relatively uniform sensitivity can be achieved at any wavelength for metal elements in the solids used in our experiments at an appropriate irradiance for the low pressure high irradiance laser ablation and ionization source. [Copyright &y& Elsevier]

This work describes a novel application of atmospheric pressure gas chromatography time-of-flight mass spectrometry (APGC-TOF-MS) combined with solid-phase microextraction (SPME) for the simultaneous analysis of hydrocarbons and naphthenic acids (NAs) species in raw and ozone-treated oil sands process water (OSPW). SPME method using polydimethylsiloxane (PDMS)-coated fibers was validated using gas chromatography with flame ionization detector (GC-FID) to ensure the SPME extractions were operated appropriately. The ionization pathways of the hydrocarbon species in OSPW in the APGC source were verified by analyzing a mixture of eight polyaromatic hydrocarbons which were ionized primarily via charge transfer to produce [M+] while NAs in OSPW were found to be ionized through protonation to generate [MH+] in the wet APGC source. SPME/APGC-TOF-MS analysis demonstrated a different composition profile in OSPW #1, with 74.5% of hydrocarbon species, 23.4% of O 2 –NAs, and 2.1% of the oxidized NA species at extraction pH 2.0 compared with that obtained by UPLC-TOF-MS analysis (36.9% of O 2 –NAs, 26.8% of O 3 –NAs, 24.9% of O 4 –NAs, 9.1% of O 5 –NAs, 2.3% of O 6 –NAs). Moreover, the peak areas of the total NAs and the total peak areas of NAs + hydrocarbons measured by SPME/APGC-TOF-MS correlated excellently with the total NA concentration determined by UPLC-TOF-MS (R2 = 0.90) and the concentrations of the total acid-extractable organics determined by SPME/GC-FID (R2 = 0.98), respectively. APGC-TOF-MS integrated with the SPME techniques could extend the range of target compounds and be a promising alternative to evaluate and characterize NAs and hydrocarbon in different water types. Image 1 • SPME coupled with APGC-TOF-MS was used for analysis of hydrocarbons and NAs. • PDMS fibers preferably extracted neutral organic compounds at natural pH. • The PDMS fibers extracted hydrocarbons and some protonated NAs species at pH 2.0 • PAHs were ionized via charge transfer while NAs were ionized through protonation. • O x -NAs peak areas by SPME/APGC-TOF-MS correlated to the O x -NAs by UPLC-TOF-MS. [ABSTRACT FROM AUTHOR]

Abstract: A newly developed two-dimensional mapping high irradiance laser ionization orthogonal time-of-flight mass spectrometer (LI-O-TOFMS) has been applied for the elemental mapping of polymetallic nodules. Two polymetallic nodule standards were used to demonstrate the efficacy of LI-O-TOFMS for the standardless semiquantitative analysis and the spatial distribution of elements in a deep-sea Pacific polymetallic nodule was mapped. It was found that the two groups of elements, Mn–Ni–Cu–Fe and Co–Si–Al, show clear element-dependent spatial relationships. It is hypothesized that these spatial distributions reflect the environmental and physico-chemical conditions during the nodule formation. LI-O-TOFMS is shown to be a powerful tool in elemental analysis of polymetallic nodules, with the detection limits down to 10−7 g/g and a dynamic range of 7 orders of magnitude. Based on the images acquired, the contents of elements and their relationships can be revealed visually. [Copyright &y& Elsevier]

Abstract: The evolution of high-irradiance laser-ionization time-of-flight mass spectrometry (LI-TOF-MS) mainly progressed following significant improvements in the laser source, the TOF mass analyzer and construction geometries. We summarize the main developments in LI-TOF-MS, including the instrumentation and the applications. We also present particular instruments that our group developed recently. [Copyright &y& Elsevier]

Abstract: Laser ablation and ionization in ambient helium and argon gases were studied by multiple-stage time-of-flight mass spectrometry. Measurements made at different gas pressures indicated that there exists an optimal pressure for adequately cooling energetic ions and reducing multiply charged ions that are higher for He than for Ar. The temporal distributions of ions were compared at various laser fluences and gas pressures, and the broad distributions for He could be ascribed to elastic scattering and thermodynamic processes. The diffusion of ions in He resulted in a longer delay before the instrument registered its maximal signal. Ions with different masses were observed to have the same kinetic energies in He, which was confirmed using the SIMION software, while ion movement was hydrodynamically controlled in Ar. The velocities of singly and doubly charged ions were also studied, and doubly charged ions showed much higher kinetic energy because of their frontal location in the plasma expansion. [Copyright &y& Elsevier]