Sample preparation procedure for the determination of polycyclic aromatic hydrocarbons in petroleum vacuum residue and bitumen

This paper describes a novel method of sample preparation for the determination of trace concentrations of polycyclic aromatic hydrocarbons (PAHs) in high-boiling petroleum products. Limits of quantitation of the investigated PAHs in materials of this type range from tens of nanograms per kilogram to <20 μg/kg. The studies revealed that in order to separate most of interferences from the analytes without a significant loss of PAHs, it is necessary to use size exclusion chromatography as the first step of sample preparation, followed by adsorption using normal-phase liquid chromatography. The use of orthogonal separation procedure described in the paper allows the isolation of only a group of unsubstituted and substituted aromatic hydrocarbons with a specific range of molar mass. The lower the required limit of quantitation of PAHs, the larger is the scale of preparative liquid chromatography in both steps of sample preparation needed. The use of internal standard allows quantitative results to be corrected for the degree of recovery of PAHs during the sample preparation step. Final determination can be carried out using HPLC-FLD, GC-MS, or HPLC-UV–VIS/DAD. The last technique provides a degree of identification through the acquired UV–VIS spectra

Observational Constraints on the Common Envelope Phase

The common envelope phase was first proposed more than forty years ago to explain the origins of evolved, close binaries like cataclysmic variables. It is now believed that the phase plays a critical role in the formation of a wide variety of other phenomena ranging from type Ia supernovae through to binary black holes, while common envelope mergers are likely responsible for a range of enigmatic transients and supernova imposters. Yet, despite its clear importance, the common envelope phase is still rather poorly understood. Here, we outline some of the basic principles involved, the remaining questions as well as some of the recent observational hints from common envelope phenomena - namely planetary nebulae and luminous red novae - which may lead to answering these open questions.Comment: 29 pages, 8 figures. To appear in the book "Reviews in Frontiers of Modern Astrophysics: From Space Debris to Cosmology" (eds. Kabath, Jones and Skarka; publisher Springer Nature) funded by the European Union Erasmus+ Strategic Partnership grant "Per Aspera Ad Astra Simul" 2017-1-CZ01-KA203-03556