A table of system constants with standard deviations and goodness-of-fit statistics at each isothermal temperature.The solutes selected were grouped into different mixtures, and then chromatographed isothermally at several temperatures to obtain their k values. The group of columns included seven ionic liquid columns and 45 non-ionic liquid columns. In order to cover a broad range of possible solute-stationary phase interactions, 95 solutes with varied functional groups were selected to perform stationary phase characterization by the SPM. Table 2 lists the correlation between system constants and the capacity of the stationary phase for various interactions. Where k is the retention factor of a solute on the stationary phase at a specific temperature c is the model intercept the capital letters ( E, S, A, B, and L) represent the solute descriptors that are probe-specific parameters determined for many substances and the lowercase letters ( e, s, a, b, and l) are referred to as the system constants, in which all information concerning the solvation properties of the stationary phase is represented. This model is described for GC by the Abraham equation: Used for many years to characterize HPLC phases, the SPM is also applicable for characterizing GC stationary phases. In contrast, the solvation parameter model (SPM) can quantitatively evaluate the individual intermolecular interactions between a substance and the stationary phase. Thus, the imprecise property of вЂpolarityвЂ™ alone is probably not sufficient to characterize GC stationary phases. However, this approach cannot fully differentiate individual interactions since the retention of probes is not driven by a single interaction, but is most often due to several simultaneous interactions.

Combining the five retention indices can then be used to determine the polarity of the stationary phase. Each probe relates to a set of solute-stationary phase interactions. The relationships of probes to compound classes are summarized in Table 1. The polarity of a GC stationary phase can be estimated using the McReynolds method, in which retention indices ( I) are determined for five test probes, representing different compound classes. They also exhibit lower column bleed, higher thermal stability, greater resistance to damage from moisture and oxygen, and longer life time when compared to columns of similar polarity. Their main advantage is that they offer different separation properties compared to columns prepared with polysiloxane polymer and polyethylene glycol stationary phases. Currently, there are seven different commercialized capillary GC columns which use ionic liquid stationary phases. While monocationic ionic liquids can be employed for industrial applications, it was discovered that dicationic and polycationic ionic liquids make suitable GC stationary phases. In fact, a quick literature search reveals a great deal of development aimed at preparing columns using ionic liquid stationary phases. These properties also make them ideal candidates as stationary phases for gas chromatography (GC).

They typically remain liquid over wide temperature ranges, and tend to exhibit low melting points, good thermal stability, negligible vapor pressure, and high viscosity. Their unique and tunable physicochemical properties are unlike any other solvent. Ionic liquids are organic salts utilized for various industrial applications. LebrГіn-Aguilar bДЄInstituto de QuГmica OrgГЎnica General (CSIC), Madrid, SpainД«Instituto de QuГmica-FГsica вЂњRocasolanoвЂќ (CSIC), Madrid, Spain Introduction Technical content was generated and provided by: The following was generated with the assistance of an outside source using Sigma-Aldrich products.

Pca column