J. Sep. Sci. 2016, 00, 1–10 1 Grzegorz Boczkaj 1 Malwina Momotko 1 Dorota Chruszczyk 1 Andrzej Przyjazny 2 Marian Kami ´ nski 1 1 Department of Chemical and Process Engineering, Chemical Faculty, Gdansk University of Technology, Gdansk, Poland 2 Kettering University, 1700 University Avenue, Flint, MI 48504, USA (E-mail: aprzyjaz@kettering.edu) Received February 11, 2016 Revised April 15, 2016 Accepted April 26, 2016 Research Article Novel stationary phases based on asphaltenes for gas chromatography We present the results of investigations on the possibility of the application of the as- phaltene fraction isolated from the oxidized residue from vacuum distillation of crude oil as a stationary phase for gas chromatography. The results of the investigation revealed that the asphaltene stationary phases can find use for the separation of a wide range of volatile organic compounds. The experimental values of Rohrschneider/McReynolds con- stants characterize the asphaltenes as stationary phases of medium polarity and selectivity similar to commercially available phases based on alkyl phthalates. Isolation of asphaltenes from the material obtained under controlled process conditions allows the production of a stationary phase having reproducible sorption properties and chromatographic columns having the same selectivity. Unique selectivity and high thermal stability make asphaltenes attractive as a material for stationary phases for gas chromatography. A low production cost from a readily available raw material (oxidized petroleum bitumens) is an important economic factor in case of application of the asphaltene stationary phases for preparative and process separations. Keywords: Asphaltenes / Gas chromatography / McReynolds constants / Selec- tivity / Stationary phases DOI 10.1002/jssc.201600183  Additional supporting information may be found in the online version of this article at the publisher’s web-site 1 Introduction Asphaltenes are a group of substances occurring in petroleum products and characterized by their physicochemical proper- ties. By definition, the asphaltene fraction consists of polar compounds insoluble in short-chain aliphatic hydrocarbons, but soluble in, among others, chlorinated organic solvents. Depending on the solvent used for their isolation and the raw material used, their color can vary from brown to black and so can their physicochemical properties [1]. Their molec- ular weight is assumed to range from ca. 700 up to almost 6000 Da [2]. The asphaltene fraction consists mostly of high- molecular-weight polycyclic aromatic hydrocarbons forming the skeleton of the molecule, surrounded by alkyl chains [3–6]. Asphaltenes also contain trace amounts of metals, that is, vanadium, iron, and nickel as well as heteroatoms – sulfur, oxygen, and nitrogen [7, 8]. The interest in this group of chemical compounds present in crude oil stems from their undesirable properties from the point of view of petroleum industry, such as formation of Correspondence: Dr. Grzegorz Boczkaj, Gdansk University of Technology, Chemical Faculty, Department of Chemical and Pro- cess Engineering, G. Narutowicza 11/12 Str., 80–233 Gdansk, Poland E-mail: grzegorz.boczkaj@gmail.com Abbreviation: FID, flame ionization detection emulsions and precipitation, including uncontrolled precip- itation in process streams, thus changing rheological prop- erties of the raw material being processed [9, 10]. Further- more, they are believed to be precursors in the formation of coke, which is one of the main problems in hydrorefining and hydrodesulfurization of heavy products and fractions of petroleum [11]. At present, the only industrial applications of asphaltenes are the production of bitumens and bitumen mixtures as well as an additive improving hardness of mineral rubber [12]. Thus far, however, the asphaltene fraction, which is a mixture of compounds having very interesting and largely unknown properties, has not been considered as a stationary phase for GC. A comprehensive literature search carried out has not revealed any papers dealing with the application of asphaltenes as stationary phases for GC. During the early development of GC, numerous mate- rials with potential applicability as stationary phases were tested, including a large number of high-molecular-weight fractions of petroleum products. Some of them have found a long-term use as stationary phases for packed columns, for example, Apiezon phases. The majority of these phases has been replaced by synthetic stationary phases with a high reproducibility of retention parameters. However, synthetic stationary phases are relatively expensive due to a multistep production process. Thus, the phases with a higher selectivity and unique separating properties find use solely in capillary C  2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.jss-journal.com