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Naphthenic acids comprise one of the most toxic compounds of the produced water released from offshore oil platforms. Therefore, developing and applying faster, simpler, and more efficient analytical methods for analyzing naphthenic acids are urgently needed. Electromembrane extraction (EME) uses the electrokinetic migration of target ions through a porous membrane. Herein, the EME method was applied to extract naphthenic acids from produced water. The EME method was optimized, and the optimal conditions encompassed decanol as the organic solvent, the sample with pH 10.0, 5 min of extraction at 200 V, and the ratio 4:1 (borate buffer/matrix, v/v). Electrochemical impedance spectroscopy confirmed charged species' migration from produced water through the EME. Subsequently, all extracts were analyzed by ultra-high-resolution mass spectrometry. The EME efficiency was assessed by comparing the extraction results to the liquid-liquid extraction (LLE) method results. Analytical results showed good linearity for both solvent and matrix curves (

Focusing on the O2 class, a set of crude oils from Llanos Orientales Basin, Colombia, were classified in terms of biodegradation levels using negative ion mode electrospray Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and chemometric analysis. The O2 class, which is mainly composed of naphthenic carboxylic acids, was monitored because these polar crude oil constituents are known to be substantially affected by microbial activity. Principal component analysis (PCA) applied on the O2 profile was able to classify the crude oils into three groups: biodegraded, mixture, and non-biodegraded. From the relative abundances of the O2 class, a clear trend on acid distribution could be directly correlated with biodegradation: a rising in abundance of saturated acids with low double-bond equivalent (DBE) values (despite the lowering observed for fatty acids with DBE = 1), expressed by the A/C index. The combined use of two indexes, the A/C index and a new index also based on saturated acid a...

Easy sonic-spray ionization mass spectrometry (EASI–MS) allows for direct and fast MS analysis of samples in ambient conditions with little or no sample preparation, therefore offering unprecedented simplicity, speed, and ease of use. EASI–MS has been shown to access the quality, type, and adulteration of biofuels and vegetable oils. Herein, EASI–MS is shown to quantitate and monitor the quality of soybean biodiesel/petrodiesel (Bn) blends. For adulteration, admixture of the parent oil has been tested and nearly instantaneous and direct EASI(+)–MS detection of as little as 1% (w/w) of soybean oil in biodiesel/petrodiesel blends was achieved. Linear analytical curves (r > 0.98) were also obtained for the quantitation of Bn blends, and the EASI(+)–MS quantitation results were compared to those obtained by nuclear magnetic resonance (NMR) spectroscopy and mid-infrared (IR) spectroscopy.

Seven gas oil (GO) cuts from the same atmospheric petroleum residuum were obtained by molecular distillation at final temperatures of 490.0 and 503.2 °C (medium GO), 522.5 and 549.5 °C (heavy GO), and 583.7, 622.4, and 662.2 °C (extra heavy GO). The detailed chemical composition of these samples was investigated using comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC–TOFMS) and electrospray ionization ultrahigh-resolution and -accuracy Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS). Many compound classes were identified by GC × GC–TOFMS, such as tri-, tetra-, and pentacyclic terpanes, steranes, and secohopanes; several polycyclic aromatic hydrocarbons (PAHs), such as fluorene, phenanthrene, pyrene, and benzo[g,h,i]perylene; sulfur compounds, e.g., alkylbenzothiophenes, alkyldibenzothiophenes, and alkylbenzonaphthothiophenes; and alkylphenols. With ESI FT-ICR MS in both the positive- and negative-ion modes, many polar components tha...

Biodiesel is composed of saturated and unsaturated methyl esters of fatty acids formed via transesterification of vegetable oil or animal fat. This chemical nature makes biodiesel much more susceptible to oxidation or autoxidation during long-term storage than conventional petrodiesel. Increasing resistance to oxidation therefore requires the use of antioxidants. This paper investigates the effectiveness of the N,N′-di-sec-butyl-p-phenylenediamine (1) as a antioxidant to improve the oxidative stability of soybean, sunflower and canola biodiesel. Results indicate that the induction period for oxidation of soybean and canola biodiesel is significantly improved with the addition of only 0.2 ppm of the 1, reaching the oxidative stability specification (6 h by the Rancimat test). For sunflower biodiesel, 2.0 ppm of the 1 was necessary. This additive is also shown to be efficiently detected by the easy ambient sonic-spray ionization mass spectrometry technique, indicating that 1 and its analogues and derivative...