title: Retention behavior of alkyl-substituted polycyclic aromatic sulfur heterocycles in reversed-phase liquid chromatography.
abstract: Retention indices for 79 alkyl-substituted polycyclic aromatic sulfur heterocycles (PASHs) were determined by using reversed-phase liquid chromatography (LC) on a monomeric and polymeric octadecylsilane (C18) stationary phase. Molecular shape parameters [length, breadth, thickness (T), and length-to-breadth ratio (L/B)] were calculated for all the compounds studied. Based on separations of isomeric methylated polycyclic aromatic hydrocarbons on polymeric C18 phases, alkyl-substituted PASHs are expected to elute based on increasing L/B ratios. However, the correlation coefficients had a wide range of values from r=0.43 to r=0.93. Several structural features besides L/B ratios were identified to play an important role in the separation mechanism of PASHs on polymeric C18 phases. First, the location of the sulfur atom in a bay-like-region results in alkylated-PASHs being more retentive than non-bay-like-region alkylated-PASHs, and they elute later than expected based on L/B value. Second, the placement of the alkyl group in the k region of the structure resulted in a later elution than predicted by L/B. Third, highly nonplanar methyl-PASHs (i.e., 1-Me and 11-MeBbN12T) elute prior to the parent PASH (BbN12T).
authors.affiliation: Chemical Sciences Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States. Electronic address: walter.wilson@nist.gov.
authors.forename: Walter B
authors.initials: WB
authors.lastname: Wilson
authors.affiliation: Chemical Sciences Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States.
authors.forename: Lane C
authors.initials: LC
authors.lastname: Sander
authors.affiliation: Chemical Sciences Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States.
authors.forename: Miren Lopez
authors.initials: ML
authors.lastname: de Alda
authors.affiliation: Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, United States.
authors.forename: Milton L
authors.initials: ML
authors.lastname: Lee
authors.affiliation: Chemical Sciences Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Wise
mesh_terms: D000478:Alkylation; D056148:Chromatography, Reverse-Phase / Q000379:methods*; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry* / Q000302:isolation & purification*; D013455:Sulfur / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D013455:Sulfur
keywords: Alkyl-substituted polycyclic aromatic sulfur heterocycles; Molecular descriptors; Polycyclic aromatic compounds; Retention behavior; Retention indices; Reversed-phase liquid chromatography stationary phases