## 1 Introduction  
Ionic liquids (ILs) present unique features that, along with their structural modularity, favor their efficient use for a variety of applications and chemical processes [1; 2; 3]. However, toxicological or environmental concerns [4], as well as some of their physico-chemical properties (like high viscosities) or their high cost, have often hampered their practical application. Many of those limitations can be overcome with the use of materials based on ILs [5]. In this context, polymeric ionic liquids (PILs) have been shown to present remarkable properties and applications [6; 7; 8; 9; 10; 11; 12], enabling new and interesting separation processes [13; 14; 15]. In the search of improved properties like negligible vapor pressure and better-symmetry peaks, new types of stationary phases in gas chromatography (GC) are constantly being explored. In this context, ionic liquids (ILs) have drawn much attention in recent years as materials for stationary phases in GC, due to properties like their capacity to establish simultaneous polar and nonpolar interactions with the analytes, their high thermal stability, or their negligible vapor pressures and wide liquid ranges [16; 17; 18; 19; 20]. Besides, it is worth mentioning that these properties can be easily fine-tuned through small changes in the structure of both the cation or the anion, which, besides, can dramatically change the selectivity or the separation capacity for the analyte of interest [21; 22; 23; 24]. Thus, for instance, the increase in the nucleophilicity of the anion can decrease the thermal stability of the corresponding ionic liquids, while its coordinating capacity can define the quality of the chromatographic separation. In this regard, stationary phases based on ionic liquids with anion halides tend to strongly retain analytes displaying hydrogen bonding donor abilities (for example, alcohols and acids), resulting in long retention times and peak asymmetry. Conversely, ILs-based stationary phases containing noncoordinating anions such as hexafluorophosphate in the IL structure often result in poor separations and overlapping peaks. In the case of ILs containing the bis[(trifluoromethyl)sulfonyl]]imide (NTT\({}_{2}\)-) anion, the resulting stationary phases have been shown to exhibit higher thermal stability and lower surface tension as compared to ILs encompassing other anions such as tetrafluorophosphate or hexafluorophosphate [25; 26; 27]. This modular character of ILs allows for a tailor-made design of new structures intending to achieve specific properties (task-specific ILs-TSILS) [28]. This can be illustrated by amino acid-based ionic liquids (AAILs). The preparation of a variety of AAILs has been reported in the literature, which allows the introduction of additional functionalities like carboxylic acid, amino, amide, or alcohol groups in the IL structure [29; 30; 31; 32]. These AAILs have additional functional groups able to provide complementary interactions such as hydrogen bonding or hydrophobic and aromatic interactions that make them interesting molecules in supramolecular chemistry being used as selective receptors or transport agents through pseudobiological membranes [33; 34]. These features also provide a strong potential for their use as stationary phases in GC, leading to the recent preparation and characterization of some new AAILs-based gas chromatography stationary phases, with good potential for the separation of the fatty acid derivatives [35]. The interest in IL-coated GC columns has increased after their commercial introduction in 2008, and nowadays, several IL-coated columns with different characteristics are commercially available. However, one major challenge for the development of stationary phases based on ILs is the preparation of highly homogenous coatings, which would favor good peak symmetries and highly effective compound separations, and concomitantly, provide high thermal stabilities for the resulting GC columns [36; 37; 38].