Coal tar has been considered as a potential energy alternative because of dwindling supplies of petroleum. To determine if the coal tar could be refined and upgraded to produce clean transportation fuels, detailed investigation of its composition is necessary, particularly for identifying the acidic components that account for about one-quarter of the weight of the coal tar. A middle-temperature coal tar (MTCT) and its fractions were characterized by gas chromatography–mass spectrometry (GC–MS) and negative-ion electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with different ion transmission modes for high- and low-mass ions. Analytical results of narrow distillation fractions from FT-ICR MS agreed reasonably well with those from GC–MS, although each technique has its own advantages and disadvantages. In this work, FT-ICR MS was demonstrated to be capable of characterizing small molecules of <100 Da using appropriate operation conditions, thus yielding mass distributions to compare to GC–MS results. A continuous distribution in double bond equivalent (DBE) and carbon number was observed with the distillates of increasing boiling point, while the composition of the distillation residue was much more complex than that of distillates. Acidic compounds containing 1–7 oxygen atoms were observed in the MTCT by FT-ICR MS, with O1 and O2 classes being dominant. Various phenolic compounds with 1–4 aromatic rings were identified on the basis of literature references, including some molecules having structures resembling known biomarkers in petroleum and coal.

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A low-temperature coal tar was subject to a three-stage catalytic hydrotreating reactor. The raw coal tar and its hydrotreating products from each reactor section were characterized by electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The removal efficiencies of sulfur, nitrogen, and oxygen were 99.4%, 88.4%, and 78.1%, respectively. The molecular transformation routes of each heteroatomic species are different. Sulfur species were removed from low double bond equivalence (DBE) values to higher values through the whole hydrotreating process. Furanic compounds and basic nitrogen compounds carried out the saturation of aromatic rings before the hydrogenation of low DBE species. Neutral nitrogen compounds were resistant in the processing and cannot be removed completely in the end of the hydroprocessing. The phenolic compounds were the most resistant to hydrotreating during the whole process. The transformation capabilities of heteroatom compounds in the processing were as follows: phenolic compounds > neutral nitrogen compounds > furanic compounds > basic nitrogen compounds > sulfur compounds.

We describe the development of a capillary electrophoresis method for the determination of gentamicin C1, C1a, C2a, and C2 components in human serum. Using a weak cation-exchanger with 20 mM phosphate buffer, pH 7.4, 200 mM borate buffer, pH 9.0, and ammonia/methanol, solid-phase extraction (SPE) of gentamicin components from the human sera was performed. The extract was derivatized with 1,2-phthalic dicarboxaldehyde/mercaptoacetic acid reagent. The derivatives were separated with a background electrolyte comprising 60 mM 2-(N-cyclohexylamino)ethanesulfonic acid (CHES) buffer at pH 9.5 containing 31.6% m/v methanol, and quantified with UV-light absorption detection at 230 nm. The identity of the gentamicin components was confirmed by mass spectrometry. The SPE recovery of the gentamicin ranged from 78% to 93%. The calibration curves were linear from the concentration limit of quantitation (LOQ) to 30 mg/L for the gentamicin mixture. The LOQ for gentamicin C1 was 0.33 mg/L, for C2a 0.23 mg/L, C2 0.25 mg/L, C1a 0.27 mg/L and the concentration limit of detection (LOD) for C1 was 0.15 mg/L, C2a 0.11 mg/L, C2 0.12 mg/L, C1a 0.13 mg/L. Intra-assay relative standard deviation (RSD) values were for C1 (5%), C1a (7%), C2 (6.5%) and C2a (9%); inter-assay RSD values were for C1 (11%), C1a (13.3%), C2 (15%) and C2a (14%). The Pearson's correlation between capillary electrophoresis and immunoassay revealed a linear relationship between these two techniques with r = 0.9. This method for determination of gentamicin C1, C1a, C2a, and C2 in human serum can thus be used in the entire therapeutic concentrations range of gentamicin.