A wide variety of biomass, from triglycerides to lignocellulosic‐based feedstock, are among promising candidates to possibly fulfill requirements as a substitute for crude oils as primary sources of chemical energy feedstock. During the feedstock processing carried out to increase the H:C ratio of the products, heteroatom‐containing compounds can promote corrosion, thus limiting and/or deactivating catalytic processes needed to transform the biomass into fuel. The use of advanced gas chromatography techniques, in particular multi‐dimensional gas chromatography, both heart‐cutting and comprehensive coupled to mass spectrometry, has been widely exploited in the field of petroleomics over the past 30 years and has also been successfully applied to the characterization of volatile and semi‐volatile compounds during the processing of biomass feedstock. This review intends to describe advanced gas chromatography–mass spectrometry‐based techniques, mainly focusing in the period 2011–early 2020. Particular emphasis has been devoted to the multi‐dimensional gas chromatography–mass spectrometry techniques, for the isolation and characterization of the oxygen‐containing compounds in biomass feedstock. Within this context, the most recent advances to sample preparation, derivatization, as well as gas chromatography instrumentation, mass spectrometry ionization, identification, and data handling in the biomass industry, are described.
Bitumen is a very viscous and complex mixture primarily used as a binder for asphalt construction. During its service life, this binder is subjected to oxidative aging, which leads to asphalt stiffness and thermal cracking of the pavement structure. The behavior of bitumen toward oxidative aging is greatly dependent on its intrinsic properties and particularly on its content of nitrogen, oxygen, and sulfur functional groups. This is of fundamental importance as the origin of the crude will influence its resistance to oxidation after several years of use in a road. It is then essential to correlate the native composition of bitumen and their corresponding oxidized products to explain changes in the physicochemical behavior of asphalt binders. Pressure aging vessel is probably the most widely used technique to simulate long-time aging of bitumen. This artificial aging technique leads to accelerated aging under high-pressure and -temperature conditions. To understand such mechanisms, characterization at the molecular level is required. Nowadays, Fourier transform ion cyclotron resonance (FTICR) is the most-used technique for the analysis of petroleum products. Bitumen samples from three different origins were subjected to PAV aging and analyzed by FTICR-MS. Coupling of electrospray ionization (ESI) and atmospheric pressure photo ionization (APPI) sources were used to provide an exhaustive characterization of the samples. Principal component analysis (PCA), which is a multivariate statistical approach, was used to separate samples according to aging and origin. Indeed, ESI coupled to PCA allowed a significant separation of samples according to their PAV-aging on the PC1 axis. PC1 scores were then used as an intensity scale to carry out a modified double bond equivalent versus carbon number (DBE vs C#) mapping. This technique allowed the characterization of specific aging markers in O z and O z S y families for each bitumen sample. In addition, PC1 coordinates were used to develop a predictive model by principal component regression (PCR). Significant differences in sensitivity to oxidation were obtained for the three bitumen samples. Concerning APPI results, less significant differences were obtained for aging compared to those obtained by ESI. PCA coupled to APPI was also used for modified DBE vs C# maps, separating samples according to their origin. Significant differences were obtained in each bitumen sample in the different compound classes (HC, S 1 , N 1 , O 1 , etc.). Overall, this study demonstrates the great interest of coupling FTICR MS data to a PCA statistical approach to characterize oxidative aging of bitumen samples according to their origin.
Rationale The offline coupling of high‐performance thin‐layer chromatography (HPTLC) with atmospheric solids analysis probe mass spectrometry (ASAP‐MS) was evaluated for the characterization of polymeric additives in gasoline. Methods A protocol was developed to optimize the ion signal. A glass capillary was moistened with deionized water, and then dipped into silica gel scratched from an HPTLC plate. The capillary tube was fixed to the ASAP holder and introduced into the ionization source for analysis by MS. Silica gel, reversed‐phase C18 and cellulose stationary phases were evaluated. Results The effect of the stationary phase and the nature of analyte were evaluated using polypropylene glycol and polyisobutylene succinimide polyamine as analyte molecules. The optimal ionization conditions are significantly different between ASAP and HPTLC/ASAP‐MS analyses. In particular, a higher desorption gas temperature was required to produce ions from the silica gel HPTLC plate. The presence of the stationary phase reduces the internal energy of the ions and limits the fragmentation. Conclusions HPTLC/ASAP‐MS is a very fast and efficient technique for the analysis of polymers in formulated fuels. Good ionization efficiency was obtained with all investigated stationary phases.
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