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We present the results of investigations on the possibility of the application of the asphaltene 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 constants 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. [ABSTRACT FROM AUTHOR]

We present the results of investigations of the chromatographic (sorptive) properties of silanized silica gel as a stationary phase for gas chromatography used for simulated distillation. Commercially available silanized sorbent (particle diameter range 63-200 μm, average pore size 60 Å) was sieved to obtain the 80-100 mesh fraction (180-150 μm). The obtained results revealed that silanized silica gel allows the complete separation of a mixture of n- and iso-alkanes in the C1-C7 range. Such a separation is achieved with a temperature program starting with an initial temperature of 50˚C, which is advantageous because the gas chromatograph oven does not have to be cooled below room temperature. The use of temperature programming with a final temperature of 300˚C ensures separation and elution of all mixture components from C1 to n-C28 in one run. This study confirms the applicability of silanized silica gel as a stationary phase for the investigation of distillation temperature distribution of gasoline and diesel fuel based on the simulated distillation procedure according to ASTM D2887. The deviations of individual points of distillation curve obtained using ASTM D2887 and columns packed with silanized silica gel were within the reproducibility range of the standard procedure. [ABSTRACT FROM AUTHOR]

• First deep eutectic solvents (DES) based GC stationary phase • Unexpected selectivity towards volatile organic compounds (VOCs) • High applicability of developed DES in separation techniques The paper presents the first application of deep eutectic solvents (DES) as stationary phases for gas chromatography. DES obtained by mixing tetrabutylammonium chloride (TBAC) as a hydrogen bond acceptor (HBA) with heptadecanoic acid being a hydrogen bond donor (HBD) in a mole ratio of HBA:HBD equal to 1:2 was characterized by its ability to separate volatile organic compounds (VOCs). The Rohrschneider – McReynolds constants determined reveal that the synthesized DES is a stationary phase of medium polarity. A detailed retention characteristic was determined for a number of groups of chemical compounds, including aromatic hydrocarbons, alcohols, ketones, sulfides and thiophene derivatives. The synthesized DES was found to have a high selectivity towards alcohols. At the same time, the investigated stationary phase was found to have specific interactions with some analytes. For example, a stronger retention was observed for 1-hexanol and 1-heptanol compared to other alcohols. Retention times of these two alcohols are longer by 191% and 300%, respectively, relative to the expected value based on their boiling point. Such an increased retention is caused by a synergistic effect of various kinds of interactions – the possibility of formation of hydrogen bonds between the DES and the hydroxyl group of alcohols and hydrophobic interactions of alkyl chains of the DES with the alkyl chain of alcohols. The ability to modify properties of DESs by replacement of HBA or HBD with a different chemical compound or by dissolving in DES macromolecular substances makes the proposed stationary phase highly flexible. In addition to using the developed DES in chromatographic techniques, the retention data collected indicate the possibility of its application to other separation techniques, i.e. extractive distillation. [ABSTRACT FROM AUTHOR]