Retention behavior of alkyl-substituted polycyclic aromatic sulfur heterocycle isomers in gas chromatography on stationary phases of different selectivity

- GC retention indices for 80 alkyl-PASHs.
- Detailed comparison of three GC stationary phases with different selectivities for alkyl-PASHs.
- First reported separations of alkyl-PASH isomers via GC on a 50% liquid crystalline DMPS phase.
- Correlations are presented between the GC retention of alkyl-PASHs and their L/B.

Retention indices for 10 sets of alkyl-substituted polycyclic aromatic sulfur heterocycles (PASHs) isomers (total of 80 PASHs) were determined using gas chromatography with three different stationary phases: a 50% phenyl phase, a 50% liquid crystalline dimethylpolysiloxane (LC-DMPS) phase, and an ionic liquid (IL) phase. Correlations between the retention behavior on the three stationary phases and PASH geometry [length-to-breadth (L/B) and thickness (T)] were investigated for the following PASHs: 4 methyl-substituted dibenzothiophenes (DBTs), 3 ethyl-substituted DBTs, 15 dimethyl-substituted DBTs, 8 trimethyl-substituted DBTs, 15 methyl-substituted naphthothiophenes, 30 methyl-substituted benzonaphthothiophenes, and 5 methyl-substituted tetrapheno[1,12-bcd]thiophene. Correlation coefficients for retention on the 50% phenyl phase vs L/B ranged from r = −0.28 (MeBbN23Ts) to r = 0.92 (EtDBTs). Correlation coefficients for retention on the IL phase vs L/B ranged from r = 0.13 (MeN12Ts) to r = 0.83 (EtDBTs). Correlation coefficients for retention on the 50% LC-DMPS phase vs L/B ranged from r = 0.22 (MeDBTs) to r = 0.84 (TriMeDBTs).