The continuous development in analytical instrumentation has brought the newly developed Orbitrap‐based gas chromatography / mass spectrometry (GC/MS) instrument into the forefront for the analysis of complex mixtures such as crude oil. Traditional instrumentation usually requires a choice to be made between mass resolving power or an efficient chromatographic separation, which ideally enables the distinction of structural isomers that is not possible by mass spectrometry alone. Now, these features can be combined, thus enabling a deeper understanding of the constituents of volatile samples on a molecular level. Although electron ionization is the most popular ionization method employed in GC/MS analysis, the need for softer ionization methods has led to the utilization of atmospheric pressure ionization sources. The last arrival to this family is the atmospheric pressure photoionization (APPI), which was originally developed for liquid chromatography / mass spectrometry (LC/MS). With a newly developed commercial GC‐APPI interface, it is possible to extend the characterization of unknown compounds. Here, first results about the capabilities of the GC/MS instrument under high or low energy EI or APPI are reported on a volatile gas condensate. The use of different ionization energies helps matching the low abundant molecular ions to the structurally important fragment ions. A broad range of compounds from polar to medium polar were successfully detected and complementary information regarding the analyte was obtained.

Rationale Characterization of complex samples remains a challenging task due to the high number of compounds present. Matrix effects, ion discrimination and suppression are limiting factors which force the use of different methods for the same sample to gain a broad understanding of complex mixtures. Methods Various ionization techniques such as electrospray ionization (ESI), atmospheric pressure photoionization (APPI) and atmospheric pressure chemical ionization (APCI) have been used in various problems for complex mixture analysis. Especially demanding is the analysis of energy‐related hydrocarbon mixtures, such as crude oil. Here, the different ionization sources alone and in combination with each other have been used on an ultrahigh resolution Orbitrap mass spectrometer to study a light crude oil. Results Despite the great variety of the available ionization sources, there is no single technique which can fully characterize the crude oil. Each ionization technique shows a selectivity towards specific types of compounds. While ESI is the method of choice for the detection of polar compounds, APPI and APCI favor the detection of nonpolar and low‐to‐medium polar compounds, respectively. The combination of ESI/APPI favors hydrocarbons and oxygen‐containing species. Conclusions Combining different ionization methods can be used as an alternative in order to gain more information about compounds present in a complex mixture although a combination of different ion sources could enhance suppression effects.

Fouling", the unwanted deposition of solids, causes significant operational difficulties in petroleum producing and processing industries and is considered a billion dollar problem. There are two routes of petroleum fouling: physical fouling, where material of low-solubility precipitates, and chemical fouling, where a chemical reaction produces insoluble material, often on the surface of heat exchangers. By implementing laboratory-scale experimental simulations of the industrial process using a petroleum derived light crude oil fraction, it is shown that chemical fouling proceeds via multistep pathways involving dehydrogenation and radical formation reactions on PAHs, resulting in the formation of carbonaceous deposits.

With the depletion of conventional resources, heavier and more sulfur-rich crude oils come into the focus of interest. However, the utilization of such feedstocks is extremely undesirable since their high sulfur content causes corrosion fouling, catalyst poisoning, and emissions of toxic pollutants into the atmosphere. As known catalyst poisoners, sulfur-containing compounds are also suspected to play an important role in crude oil fouling, that is, the formation of undesired solid deposits. To overcome these problems, insightful knowledge on the chemical composition of the sulfur-containing compounds on a molecular level and their behavior is necessary. Here, fouling reactions of a gas condensate were simulated in the laboratory under atmospheric and inert conditions, with special focus on sulfur-containing compounds, and the resulting mixtures were analyzed by using sophisticated analytical methods such as ultrahigh-resolution mass spectrometry and electron microscopy. The results indicate that sulfur-containing compounds decompose at elevated temperatures, partly by a radical-induced mechanism. Furthermore, the resulting intermediates show a limited stability in the presence of oxygen.