Retention Behaviour of Alkylated and Non-Alkylated Polycyclic Aromatic Hydrocarbons on Different Types of Stationary Phases in Gas Chromatography

Abstract

The gas chromatographic retention behaviour of 16 polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs on a new ionic liquid stationary phase, 1,12-di(tripropylphosphonium) dodecane bis(trifluoromethanesulfonyl)imide (SLB ® -ILPAH) intended for the separation of PAH mixtures, was compared with the elution pattern on more traditional stationary phases: a non-polar phenyl arylene (DB-5ms) and a semi-polar 50% phenyl dimethyl siloxane (SLB PAHms) column. All columns were tested by injections of working solutions containing 20 parental PAHs from molecular weight of 128 to 278 g/mol and 48 alkylated PAHs from molecular weight of 142 to 280 g/mol on a one dimensional gas chromatography-mass spectrometry (GC-MS) system. The SLB PAHms column allowed separation of most isomers. The SLB ® -ILPAH column showed a rather different retention pattern compared to the other two columns and, therefore, provided a potential for use in comprehensive two-dimensional GC (GC×GC). The ionic liquid column and the 50% phenyl column showed good thermal stability with a low bleed profile, even lower than that of the phenyl arylene "low bleed" column.In non-occupational settings, food is the main source of human exposure to PAHs, followed by cigarette smoke, which in some cases may result in PAH exposure on par with the food uptake route [4,5]. Other important exposure routes include traffic related air pollution and all kinds of occupational exposures. Nonetheless, the new possible exposure pathways are still being identified: e.g. synthetic turf materials used on football fields [6].The analysis of PAHs is generally based on gas chromatography (GC) rather than on liquid chromatography (LC) because GC allows greater selectivity, resolution and sensitivity than LC [7,8]. The GC systems are commonly coupled with flame ionisation detectors (FID) or mass-spectrometric detectors (MS). The GC analysis was conventionally based on non-polar stationary phases operated at relatively high temperatures [8,9]. The 5% phenyl methylpolysiloxane phase (like in the DB-5 column) is still the most often applied one in PAHs analysis and it has also been recommended in a number of US-EPA methods, e.g. US EPA method 610 [10]. Since the 1990s, high phenyl content stationary phases have been more frequently used, e.g. described by the producers as "50% phenyl methylpolysiloxane-like" DB-17MS [8,11], Rxi-PAH [12] or SLB PAHms [13].Some years ago, a new group of stationary phases, based on non-bonded ionic liquids (IL) was introduced [14,15]. Based on non-molecular solvents with low melting points, these stationary phases consist of organic cations plus inorganic or organic anions [16] and, therefore, the IL columns enable chromatographic separation based on a selectivity different to that provided by conventional stationary phases. Some IL columns can exhibit "dual nature" features; they allow separation of non-polar molecules as non-polar stationary phases do, while at the same time they have a high affinity for polar molecules like polyethylene glycol (wax)...

The role of receptor‐mediated activities of 4‐ and 5‐ring unsubstituted and methylated polycyclic aromatic hydrocarbons (PAHs) in developmental toxicity

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