Variation of anionic moieties of dicationic ionic liquid GC stationary phases: Effect on stability and selectivity Mohsen Talebi a , Rahul A. Patil a , Leonard M. Sidisky b , Alain Berthod c , Daniel W. Armstrong a, * a Department of Chemistry and Biochemistry, University of Texas at Arlington, 700 Planetarium Place, Arlington, TX, 76019, USA b Millipore-Sigma, Bellefonte, PA, 16823, USA c Institut des Sciences Analytiques, Universit e de Lyon 1, CNRS, 5 rue de la Doua, 69100, Villeurbanne, France highlights graphical abstract  14 newly synthesized dicationic ionic liquids varying by the anion.  A McReynolds polarity passing 6000 or polarity number of 143.  Strong selectivity differences be- tween polar and apolar solutes.  Anthracene eluting BEFORE phenan- threne showing unique shape selectivity. article info Article history: Received 11 June 2018 Received in revised form 19 July 2018 Accepted 22 July 2018 Available online xxx Keywords: Dicationic ionic liquids Physicochemical properties Capillary GC columns FAMEs BAMEs PAHs Biodiesel Selectivity Polarity abstract Dicationic ionic liquids (DILs) are more and more accepted as a new class of high temperature and polar stationary phases for gas chromatography (GC). This study deals with the effect of seven different flu- orosulfonyl derivatized anions associated with two dications: 1,3-di(3-methylimidazolium)-2- methylpropane [2mC 3 (mim) 2 ], and 1,3-di(3-methylimidazolium)-isobutene [i-eneC 4 (mim) 2 ]. Thermo- physical properties of the 14 synthesized DILs were evaluated in terms of melting point, viscosity, and thermal stability. The optimal physicochemical properties of 13 DILs allowed preparing 13 GC capillary columns. Accordingly, the polarity and selectivity of the DILs were evaluated by determining the Rohrschneider-McReynolds constants and the equivalent chain lengths of C18 fatty acid methyl esters (FAMEs). The symmetrical fluoroalkylsulfonyl and the trifluorosulfonate anions seem to produce the most polar DILs. Compared to classical polyethyleneglycol phases, the DILs showed substantially decreased retention of apolar compounds and a much stronger retention of the polar ones. Unique se- lectivities were observed with unsaturated FAMEs, polyaromatic hydrocarbons, and bacterial specific FAMEs. The two applications presented included a biodiesel and bacterial FAME analyses. © 2018 Elsevier B.V. All rights reserved. 1. Introduction Classical polar materials used as stationary phases in gas chro- matography (GC) were traditionally significantly less thermally stable than their apolar polysiloxane counterparts. For decades, polar * Corresponding author. E-mail address: sec4dwa@uta.edu (D.W. Armstrong). Contents lists available at ScienceDirect Analytica Chimica Acta journal homepage: www.elsevier.com/locate/aca https://doi.org/10.1016/j.aca.2018.07.047 0003-2670/© 2018 Elsevier B.V. All rights reserved. Analytica Chimica Acta xxx (2018) 1e10 Please cite this article in press as: M. Talebi, et al., Variation of anionic moieties of dicationic ionic liquid GC stationary phases: Effect on stability and selectivity, Analytica Chimica Acta (2018), https://doi.org/10.1016/j.aca.2018.07.047