The 16 EPA PAHs have played an exceptionally large role above all in environmental and analytical sciences in the last 40 years, but now there are good reasons to question their utility in many circumstances even though their use is so established and comfortable. Here we review the reasons why the list has been so successful and why sometimes it is seen as less relevant. Three groups of polycyclic aromatic compounds (PAC) are missing: larger and highly relevant PAHs, alkylated PACs, and compounds containing heteroatoms. Attempts to improve the situation for certain matrixes are known and here: (1) an updated list of PAHs (including the 16 EPA PAHs) for the evaluation of the toxicity in the environment (40 EnvPAHs); (2) a list of 23 NSO-heterocyclic compounds and 6 heterocyclic metabolites; and (3) lists of 10 oxy-PAHs and 10 nitro-PAHs are proposed for practical use in the future. A discussion in the scientific community about these lists is invited. Although the state of knowledge has improved dramatically since the introduction of the 16 EPA PAHs in the 1970s, this summary also shows that more research is needed about the toxicity, occurrence in the environment and chemical analysis, particularly of alkylated PAHs, higher molecular weight PAHs and substituted PACs such as amino-PAHs, cyano-PAHs, etc.. We also suggest that a long overdue discussion of an update of regulatory environmental PAH analysis is initiated.

Millions of tons of vacuum residues are produced in refineries every year and could be a potentially valuable resource for generating electricity and has possible application as heating and marine fuel. In this work, the polycyclic aromatic sulfur compounds (PASHs) from the aromatic fraction of vacuum residue before and after partial hydrodesulfurization (HDS) were derivatized by methylation to the methylsulfonium salts. Fourier transform ion cyclotron resonance mass spectrometry provided high-resolution data on these high-molecular-weight sulfur compounds. Compounds containing one and two S atoms were found to dominate, with masses up to ca. 900 Da. Classification according to hydrogen deficiency and the number of heteroatoms showed extensive series of homologues for double bond equivalents from 5 to 20. The sulfur-containing aromatics were separated using a palladium(II) complex as a liquid chromatographic phase into two compound groups: one containing compounds with an unconjugated thiophene ring and another with a condensed thiophene ring. This, combined with the mass spectrometry (MS) data, allows for the identification of several parent structures. Partial HDS removed primarily compounds with one S atom, whereas those with two S atoms were largely unaffected.

Through different windows: One major obstacle in energy research is the complexity and variety of compounds present in crude oil. A study of different ionization methods for mass spectrometry shows that the mass spectrum very strongly depends on which method is used.

Inhaltsangabe: Eine große Hürde für eine optimale Energiegewinnung aus Erdöl ist die Komplexität und Vielfalt der darin enthaltenen Verbindungen. Eine Untersuchung verschiedener Ionisierungsmethoden für die Massenspektrometrie ergibt, dass das Massenspektrum einer Erdölprobe stark von der jeweils verwendeten Methode abhängt.

The chemical group of polycyclic aromatic compounds (PAC), including the better-known subgroup of polycyclic aromatic hydrocarbons (PAH) and the heterocyclic aromatic compounds (NSO-PAC, heterocycles), comprise several thousand individual compounds. It is hard to find a comprehensive overview in the literature of these PACs that includes a substantial amount of relevant properties. Here an attempt is made to summarize the most studied but also some less well-known PACs. In addition to basic data such as recommended names, abbreviations, CAS numbers, molecular formulas, chemical structures, and exact mono-isotopic molecular weights, physico-chemical properties taken from the literature like boiling points, vapor pressures, water solubilities, Henry's Law constants, n-octanol-water partition coefficients (log KOW), and pKa are summarized. Selected toxicological data are listed indicating carcinogenic and mutagenic activity or effects on different organisms.PAC nomenclature is a complex topic, so suggestions for practical use are made. Regarding available data, estimated (instead of measured) values should be used with caution because considerable deviations from experimentally determined values can occur. For an enhanced understanding of the behavior of single PACs in comparison with each other, some of the properties mentioned above are plotted vs. the number of rings or the degree of alkylation. Also, some physico-chemical data are correlated with different functional groups as substituents of the PAHs.This article reveals that rather little is known about the less common PACs, e.g., higher molecular weight compounds, alkylated or otherwise substituted aromatics, for instance, keto-, oxo-, amino-, nitro-, cyano-PAHs, or some heterocyclic aromatic compounds, including their derivatives. It mirrors the limited state of knowledge about the variety of PACs that do not belong to the 16 EPA PAHs.