Quantitative Molecular Characterization of Petroleum Asphaltenes Derived Ruthenium Ion Catalyzed Oxidation Product by ESI FT-ICR MS

Molecular structure of heavy petroleum could be investigated by the composition of its ruthenium ion catalyzed oxidation (RICO) products. However, the interpretation of the results was not comprehensive due to the limited compositional information obtained solely by gas chromatography (GC) analysis. In this study, a semiquantitative method based on electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was established and applied for the molecular characterization of RICO products. Thousands of polar compounds were detected by negative-ion ESI FT-ICR MS in the RICO products of the Canadian oil sands bitumen derived asphaltenes. Besides alkyl carboxylic acids, naphthenic acids with one to five naphtha rings, nitrogen- and sulfur-containing carboxylic acids, and acidic compounds with multioxygen atoms were observed. The upper carbon number limit of alkyl moieties connected to the aromatic cores of the asphaltenes was found up to 60, which is much higher than the results derived from GC analysis. Normal and isomer alkyl carboxylic acids, as well as naphthenic acids, were quantitatively analyzed separately. The quantitative results of alkyl carboxylic acids from ESI FT-ICR MS agreed well with the GC results. The FT-ICR MS results indicate that additional compositional information could be obtained from RICO analysis. In addition, the method is instructive for the development of quantitative analysis technology for petroleum molecular characterization based on ESI FT-ICR MS

Raw data of GCMS, Orbitrap MS and FT-ICR MS

The Raw data of GCMS, Orbitrap MS and FT-ICR M

FT-ICR MS and Orbitrap MS data in Excel format

FT-ICR MS and Orbitrap MS data in Excel forma

Ion Transport Traversing Bioinspired Ion Channels at Bionic Interface

Ion transport is especially crucial in normal body function, which is regulated by specialized ion channels. In this report, the simple hydrophilic alumina nanochannel is constructed at liquid/liquid (L/L) interface to simulate veritably and compactly complex cross-channel ion transfer processes of living systems in a similar physiological saline environment. The selectivity and regulation that are known for being two important characteristics of ion channels were achieved due to controllable electrosurface properties of alumina nanochannel. This channel shows good selectivity for ion with low electronegativity. The regulatory role of ion channel in confined space was achieved by varying diameters of nanochannel and lengths of ions travel path. In addition, a new theory based on the Randles-Sevcik equation is proposed for evaluation of cross-channel ion transfer in this article for the first time. The ingenious design strategy is demonstrated to be a useful means for investigating the complex cross-channel ion transport

Molecular Structure of Heavy Petroleum: Revealed by Molecular Composition of Ruthenium-Ion-Catalyzed Oxidation Products

Ruthenium-ion-catalyzed oxidation (RICO) is an approach for investigating the structure of heavy oils by selectively removing aromatic carbon from petroleum fractions, while leaving the structural integrity of aliphatic units intact. Six petroleum vacuum residue (VR) samples originating from various sources were separated into saturate, aromatic, resin, and asphaltene (SARA) fractions. The aromatics, resins, and asphaltenes were subjected to the RICO reaction, and the products were characterized by gas chromatography (GC) and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The alkyl side chains on aromatic cores of various VRs were significantly different in terms of their contents and carbon number distribution ranges. Normal alkyl side chains were dominant in all VRs; isoparaffin side chains were ubiquitous but in low concentrations, even in severely biodegraded oils. The content of the methyl group was much more than those of other alkyl groups and the content of the side chain decreased with an increased carbon number. For a given VR, the aromatics, resins, and asphaltenes had similar alkyl side chains, especially for aromatics and resins. The archipelago structures were rare, if they existed; nevertheless, asphaltenes appeared to have relatively more archipelago structures than aromatics and resins. FT-ICR MS analysis indicated that many structural moieties, except alkyl side chains, were connected to aromatic cores, which were abundant. The upper limits of the carbon number of alkyl chains determined by FT-ICR MS analysis were much higher than those obtained by GC analysis. For a given VR, the upper limits of the side chain carbon number in aromatics, resins, and asphaltenes were comparable. The relative abundances of short chains and naphthenic structures in asphaltenes were higher than those in resins and aromatics

Improved Sensing in Physiological Buffers by Controlling the Nanostructure of Prussian Blue Films

The electrochemical properties of a Prussian blue (PB) electrode were improved by introducing cetyltrimethylammonium bromide (CTAB) and Au nanoparticles (AuNPs) into PB films. The novel hybrid films (PB/CTAB/AuNPs) were fabricated by electrodepositing PB and AuNPs in the presence of CTAB. The electrochemical behavior of the hybrid film in some supporting electrolyte (cations for the K+, Na+, or K+/Na+) was investigated in detail, and well-defined and reversible voltammetric responses were obtained in Na+-based electrolytes. The catalytic activity of the PB/CTAB/AuNPs electrode toward hydrogen peroxide (H2O2) reduction at a neutral pH was also investigated, and the results indicated that the electrochemical reduction of H2O2 in the presence of physiological levels of Na+ was superior to that of a PB-modified electrode. Moreover, the PB/CTAB/AuNPs electrode exhibited good performance, a low detection limit (0.1 μM), and high stability at a wide range of concentrations (0.882−195 μM). To determine the performance of PB nanocomposite electrodes in Na+-based phosphate buffers, an amperometric biosensor with a PB/CTAB/AuNPs electrocatalyst was developed. To fabricate this sensor, the enzyme was immobilized in sol−gel and was electrodeposited onto a PB nanocomposite film. The results indicated that the biosensor can be used at a wide range of concentrations (20−400 μM) and possesses a low detection limit (7 μM) for glucose. These characteristics demonstrate that PB nanocomposite film can be used as an electron mediator for biosensors in potassium-free phosphate buffers

Analysis of Saturated Hydrocarbons by Redox Reaction with Negative-Ion Electrospray Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

A novel technique was developed for characterization of saturated hydrocarbons. Linear alkanes were selectively oxidized to ketones by ruthenium ion catalyzed oxidation (RICO). Branched and cyclic alkanes were oxidized to alcohols and ketones. The ketones were then reduced to alcohols by lithium aluminum hydride (LiAlH₄). The monohydric alcohols (O₁) in the products obtained from the RICO and RICO-LiAlH₄ reduction reactions were characterized using negative-ion electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) for identification of <i>iso</i>-paraffins, acyclic paraffins and cyclic paraffins. Various model saturated compounds were used to determine the RICO reaction and ionization selectivity. The results from the FTICR MS analysis on the petroleum distillates derived saturated fraction were in agreement with those from field ionization gas chromatography time-of-flight mass spectrometry (FI GC-TOF MS) analysis. The technique was also used to characterize a petroleum vacuum residue (VR) derived saturates. The results showed that the saturated molecules in the VR contained up to 11 cyclic rings, and the maximum carbon number was up to 92