Immobilized ionic liquid -siloxane hybrid stationary phase for gas chromatography

Abstract

Chromatography columns are disclosed. The column includes a coating on an inner surface. The coating on the inner surface includes a cross-linkable reactive polymer and ionic functional groups. The cross -linkable reactive polymer has one or more functional groups that are attached to the inner surface. Chromatography systems including columns are disclosed. Methods of adjusting the selectivity of chromatography columns with ionic functional groups are also disclosed.

Description

[0001] Attorney Docket No.: A2208-7006WO

[0002] IMMOBILIZED IONIC LIQUID-SILOXANE HYBRID STATIONARY PHASE FOR GAS CHROMATOGRAPHY

[0003] CROSS REFERENCE TO RELATED APPLICATIONS

[0004] This application claims priority to U.S. Patent Application No. 63 / 738,653, filed December 24, 2024, the entire contents of which are incorporated herein by reference in their entirety.

[0005] SUMMARY OF THE INVENTION

[0006] In accordance with an aspect, there is provided a chromatography column. The column may include a coating on an inner surface. The coating on the inner surface may include a cross -linkable reactive polymer and ionic functional groups. The cross -linkable reactive polymer may have one or more functional groups that are attached to the inner surface.

[0007] In some embodiments, the cross-linkable reactive polymer may include a siloxane backbone. For example, the siloxane backbone can be a polydimethylsiloxane (PDMS) backbone. When PDMS is the backbone of the cross -linkable reactive polymer, the one or more functional groups may be covalently bonded to the PDMS backbone.

[0008] In some embodiments, the one or more functional groups may include vinyl

[0009] (-CH=CH2), tolyl (CH3C6H4-R), peroxides (R-O-O-R), acrylates (CH2=CHCO2), hydrogen, methacrylate (C4H5O2”), epoxy (R0-O-R2), hydroxyl (OH- ), thiol (R-SH), and amine (R1R2R3-N). The one or more functional groups may be cross-linked to the inner surface.

[0010] In some embodiments, the cross-linkable reactive polymer may include one or more reactive functional groups selected from haloalkyl, haloalkenyl, halophenyl, and haloalkylphenyl. The reactive functional groups of the cross-linkable reactive polymer may react to form the ionic functional groups that are covalently bonded on the cross -linkable reactive polymer. For example, the one or more reactive functional groups can react with a nucleophilic reagent to form the ionic functional groups, e.g., nucleophilic substitution. In certain embodiments, the nucleophilic reagent may include substituted or unsubstituted amines, substituted or unsubstituted phosphines, and thioethers. The nucleophilic reagent may be used neat or may be used as a precursor for another nucleophile.

[0011] In some embodiments, a cationic end of the ionic functional groups may be covalently bonded to the cross -linkable reactive polymer. In further embodiments, an anionic end of the ionic functional groups may be exchangeable. For example, the exchange of the anion of theAttorney Docket No.: A2208-7006WO

[0012] anionic end of the ionic functional groups may be used to adjust one or more of column selectivity, column thermal stability, and column inertness.

[0013] In accordance with an aspect, there is provided a chromatography system. The system may include an enclosure. The enclosure may include chromatography column, a sample inlet connectable to a first end of the chromatography column, and a detector connectable to a second end of the chromatography column. The chromatography column of the system may include a coating on an inner surface. The coating on the inner surface may include a cross -linkable reactive polymer and ionic functional groups. The cross -linkable reactive polymer may have one or more functional groups that are attached to the inner surface.

[0014] In some embodiments, the one or more functional groups may be cross -linked to the inner surface.

[0015] In some embodiments, the ionic functional groups may include a cationic end and an anionic end. In some embodiments, a cationic end of the ionic functional groups may be covalently bonded to the cross -linkable reactive polymer. In further embodiments, an anionic end of the ionic functional groups may be exchangeable, e.g., to adjust one or more properties of the coating on the column. In further embodiments, exchange of the anion of the anionic end of the ionic functional groups may adjust one or of column selectivity, column thermal stability, and column inertness of the coating on the chromatography column. As a nonlimiting example, exchange of the anion of the anionic end may increase thermal stability of the coating.

[0016] In some embodiments, exchange of the anionic end of the ionic functional groups may result from contact of the coating with a solution comprising an anion different than the anionic end. Exchangeable anions may include, but are not limited to, hexafluorophosphate (PF6-), tetrafluoroborate (BF4-), bis(trifluoromethylsulfonyl)imide, i.e., bistriflimide (NTf2, [(CF3SO2)2N]-, trifluoromethanesulfonate, i.e., triflate [(OSCFCFa)]-, dicyanamide (C2N3)“, dimethylphosphate (C2H6O4P)-, acetate, bisulfate (HSCU)-, and ethyl sulfate (CH3CH2OSO3)-.

[0017] In accordance with an aspect, there is provided a method of adjusting a selectivity of a chromatography column. The method may include performing a separation of a sample using the column. The chromatography column may include a coating on an inner surface. The coating may include a cross-linkable reactive polymer and ionic functional groups comprising a cationic end and an anionic end. The method may include evaluating a separation performance of the chromatography column. The method further may includeAttorney Docket No.: A2208-7006WO

[0018] contacting the coating with a solution containing an anion different than the anionic end to exchange the anions in the coating.

[0019] In some embodiments, exchanging the anions in the coating does not remove the coating from the inner surface.

[0020] In some embodiments, the cross-linkable reactive polymer may have one or more functional groups that are attached to the inner surface.

[0021] In some embodiments, the solution for exchanging anions may include a salt solution, e.g., an ionic liquid. Exchangeable anions in the salt solution may include, but are not limited to, hexafluorophosphate (PFe-), tetrafluoroborate (BF4-), bis(trifluoromethylsulfonyl)imide, i.e., bistriflimide (NTfz, [(CFaSCE N]-), trifluoromethanesulfonate, i.e., triflate (OSChCFa)-. dicyanamide (C2N3)-, dimethylphosphate (C2H6O4P)-, acetate (CFFCOO)-, bisulfate (HSCU)-, and ethyl sulfate (CFFCFhOSOs)-.

[0022] BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

[0024] FIG. 1 is an illustration of a chromatography column in accordance with this disclosure;

[0025] FIG. 2 illustrates a chromatography system in accordance with this disclosure;

[0026] FIG. 3A illustrates one method of preparing a chromatography column in accordance with this disclosure;

[0027] FIG. 3B illustrates another method of preparing a chromatography column in accordance with this disclosure;

[0028] FIG. 4 provides the formalism for the calculation of McReynolds index numbers for probes used to evaluate polarity of a stationary phase;

[0029] FIG. 5 provides the formalism for the calculation of CP-index numbers for ranking the polarity of a stationary phase;

[0030] FIGS. 6A-6C illustrate the reaction pathways for the formation of the coating to be applied to chromatography columns of this disclosure;

[0031] FIG. 7 illustrates the Fourier Transform infrared (FT-TR) spectrum of a coating for a chromatography column in accordance with this disclosure; andAttorney Docket No.: A2208-7006WO

[0032] FIG. 8 illustrates the McReynolds index numbers and CP-index numbers of a coating for a chromatography column in accordance with this disclosure.

[0033] DETAILED DESCRIPTION

[0034] This disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” “having,” “containing,” “involving,” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

[0035] Ionic liquids (ILs) have become recognized in gas chromatography (GC) as stable and highly polar stationary phases suitable for a wide range of applications. Having customizable molecular structures, ILs also offer a unique tunability that provides additional selectivity, and therefore may improve separation for neighboring analytes. Separation in GC using conventional stationary phases, such as poly(siloxane) and poly(ethylene glycol), is mainly achieved as a result of the vapor pressure and polarity difference between the separated compounds and phases. This separation mechanism often limits the separation power for target regions and the chemical interactions that can be exploited in one-dimensional GC. Specialty stationary phases, such as those based on liquid crystals and chiral phases are example stationary phases that offer targeted separations simply not possible with conventional stationary phases. The number of stationary phases that can be effectively applied in multidimensional GC, where at least two columns are used to increase the number of compounds that can be separated and identified in an analysis, is also limited because of a lack of selectivity variation amongst available columns, and some compounds might not be adequately separated.

[0036] ILs have shown to be difficult to immobilize inside a conventional GC capillary column, generally made from fused silica. Immobilization is preferred, for example, to increase the resistance or mechanical stability of the coated phase against “on column” liquid injections or column rinsing. Immobilization should, however, not affect the permeation properties of the underlying polymer layer. If the ILs lose their liquid properties due to immobilization, the permeation properties are potentially lost, rendering them unsuitable as a stationary phase. Recent work has shown that hybrid IL-siloxane stationary phases with a high thermalAttorney Docket No.: A2208-7006WO

[0037] stability and unique polar selectivity due to the presence of the incorporated ionic groups can be produced. These hybrid IL- siloxane stationary phases were not immobilized and were susceptible to mechanical failure due to column rinsing, elevated GC oven temperatures, and unfavorable interactions with directly injected liquids.

[0038] One potential challenge with the use of pure ILs as a stationary phase is the difficulty of getting an even spreading of the IL inside the GC column. Even spreading, i.e., a constant film thickness over the length of the column, is necessary to obtain a proper plate count (Nth) for the resulting GC column. As ILs are highly polar, they exhibit high surface tension and thus even spreading in a GC column generally necessitates surface roughening using NaCl colloidal solutions, e.g., sol, or application onto bare deactivated fused silica. When using a sol or using bare, un-deactivated, fused silica, there is a risk that polar analytes will show unwanted interactions with the non-deactivated GC column wall. This can lead to unwanted adsorption effects of these analytes. Low inertness (As) will express itself as peak tailing or partial peak loss, which will lead to disturbance and decreased reliability. It is an object of this disclosure to provide for a hybrid IL-siloxane stationary phase that is mechanically immobilized to the inner surface of a column such that the column has high mechanical and thermal stability along with tunable selectivity.

[0039] Disclosed herein are chromatography columns, e.g., GC columns, and chromatography systems having a stationary phase including a siloxane and an ionic liquid in the column. In particular, the column includes a coating on an inner surface. The coating includes a cross-linkable reactive polymer and ionic functional groups. The cross-linkable reactive polymer of the coating includes one or more functional groups that are attached to the inner surface.

[0040] An embodiment of a chromatography column is illustrated in FIG. 1. With reference to FIG. 1, column 100 includes a wall 102 with an inner surface 104 that includes a crosslinkable reactive polymer 106 attached to the inner surface 104. The attachment between the cross-linkable reactive polymer 106 and the inner surface 104 immobilizes the cross-linkable reactive polymer 106. The cross -linkable reactive polymer 106 includes one or more functional groups 107 that provide the attachment to the inner surface 104. The crosslinkable reactive polymer 106 further includes ionic functional groups 108 that act as the reactive portion of the chromatography column 100, i.e., interact with samples directed through the chromatography column 100. The ionic functional groups 108 include a cationic end 108a that is coordinated to the cross-linkable reactive polymer 106 and an anionic end 108b that interacts with samples directed through the chromatography column 100. TheAttorney Docket No.: A2208-7006WO

[0041] cross-linkable reactive polymer 106 includes a siloxane backbone, e.g., polydimethylsiloxane (PDMS). In specific embodiments, the PDMS includes the one or more functional groups 107 that provide the attachment to the inner surface 104 and ionic functional groups 108.

[0042] The one or more functional groups 107 that provide the attachment to the inner surface 104 are covalently bonded to the siloxane backbone of the cross -linkable reactive polymer 106. The one or more functional groups 107 can be any functional group that can be cross-linked to the fused silica of the chromatography column 100. For example, the one or more functional groups 107 can be one or more of vinyl (-CH=CH2), tolyl (CH3C6H4-R), peroxides (R-O-O-R), acrylates (CH2=CHCO2), hydrogen, methacrylate (C4HsO2~), epoxy (R0-O-R2), hydroxyl (OH- ), thiol (R-SH), and amine (R1R2R3-N). In some embodiments, the one or more functional groups 107 are thermally cross-linked to the inner surface 104 to immobilize the coating to the wall 102. The time and temperature for the cross-linking reactions are in part dependent on the identity of the one or more functional groups and would be known to one of skill in the art.

[0043] In some embodiments, the cross-linkable reactive polymer 106 includes one or more reactive functional groups that serve as reaction sites for chemical modification. As disclosed herein, the one or more reactive functional groups are reacted to form the ionic functional groups that are part of the coating. The one or more reactive functional groups can be any functional group that has reactivity for a nucleophile, e.g., nucleophilic attack or nucleophilic substitution, using a suitable nucleophilic reagent. For example, the one or more reactive functional groups may include, but are not limited to, halide, e.g., haloalkyl, haloalkenyl, halophenyl, and haloalkylphenyl. Other electrophiles that can react in this manner are within the scope of this disclosure. Upon the reaction with the nucleophilic reagent, the resultant ionic functional group 108 has the cationic end 108a covalently bound to the cross -linkable reactive polymer 106. The anionic end 108b is exposed and can be further reacted, e.g., ion exchange.

[0044] As disclosed herein, ion exchange of the anionic end 108b can be used to adjust one or more of column selectivity, column thermal stability, and column inertness. As a nonlimiting example, halide ions present in stationary phases are known to reduce thermal stability. Substitution with an anion having a greater charge distribution, e.g., hexafluorophosphate (PFe-), tetrafluoroborate (BF4-), bis(trifluoromethylsulfonyl)imide, i.e., bistriflimide (NTfz, [(CFsSCh N]-), trifluoromethanesulfonate, i.e., triflate (OSChCFd-. dicyanamide (C2N3)-, dimethylphosphate (C2H6O4P)-, acetate (CH .COO)-, bisulfate (HSC )-, and ethyl sulfate (CFFCFhOSCF)-, can increase thermal stability of the coating. AsAttorney Docket No.: A2208-7006WO

[0045] another non-limiting example, column inertness generally refers to the surface characteristics of the column wall. If the coating of the column wall shows strong interactions with analytes, it would be revealed in the chromatograms as unwanted peak distortions, such as peak tailing or adsorption, or distortions due to impurities. Adjustment of the anionic end 108b of the coating can substantially improve inertness, reducing peak distortions. Other adjustments to one or more functional properties of the coating via the anionic end 108b are within the scope of this disclosure.

[0046] Further provided in this disclosure are chromatography systems, e.g., for use in separations of one or more analytes from a sample. The system includes a chromatography column, e.g., as disclosed herein. The chromatography column of the system includes a coating on an inner surface that is attached, i.e., immobilized on the inner surface. The coating has a cross -linkable reactive polymer with one or more functional groups and ionic functional groups. A system of this disclosure is illustrated in FIG. 2. In FIG. 2, chromatography system 200 includes an enclosure 201 having a sample inlet 202, a column 204, e.g., a column as disclosed herein, e.g., column 100 of FIG. 1, connected at a first end to the sample inlet 204, and a detector 206 connected at a second end of the column 204. The enclosure 201 may be a thermally controllable enclosure, e.g., an oven. In addition to the chromatography column, e.g., as disclosed herein, sample inlet, and detector, systems of this disclosure include other components required for operation of the system. For example, systems can include, but are not limited to, pressurized carrier gases, valves, detectors, and other related components.

[0047] In some embodiments, the ionic functional groups may include a cationic end and an anionic end. In some embodiments, a cationic end of the ionic functional groups may be covalently bonded to the cross -linkable reactive polymer. In further embodiments, an anionic end of the ionic functional groups may be exchangeable, e.g., to adjust one or more properties of the coating on the column. In further embodiments, exchange of the anion of the anionic end of the ionic functional groups may adjust one or of column selectivity, column thermal stability, and column inertness of the coating on the chromatography column. As a nonlimiting example, exchange of the anion of the anionic end may increase thermal stability of the coating.

[0048] In some embodiments, exchange of the anionic end of the ionic functional groups results from contact of the coating with a solution, e.g., a salt comprising an anion different than the anionic end. Exchangeable anions include, but are not limited to, hexafluorophosphate (PFe-), tetrafluoroborate (BF4-), bis(trifluoromethylsulfonyl)imide, i.e.,Attorney Docket No.: A2208-7006WO

[0049] bistriflimide (NTf2, [(CFaSCh N] , trifluoromethanesulfonate, i.e., triflate [(OSO2CF3)] , dicyanamide (C2N3)-, dimethylphosphate (C2H6O4P)-, acetate, bisulfate (HSC )-, and ethyl sulfate (CH3CH2OSO3)’.

[0050] In accordance with an aspect of this disclosure, provided are methods of adjusting a selectivity of a chromatography column. The method includes performing a separation of a sample using the column. The chromatography column may include a coating on an inner surface, e.g., as disclosed herein, e.g., a coating with a cross-linkable reactive polymer and ionic functional groups having a cationic end and an anionic end. The method includes evaluating a separation performance of the chromatography column, e.g., peak height, peak area, and / or peak shape. Other separation performance evaluation metrics, e.g., plate number, separation indexes, and the like, are within the scope of this disclosure. The method further includes contacting a solution containing an anion different than the anionic end of the coating to exchange the anions in the coating.

[0051] In some embodiments, exchanging the anions in the coating does not remove the coating from the inner surface, i.e., the coating is attached, e.g., immobilized, e.g., crosslinked, to the inner surface.

[0052] In some embodiments, the cross-linkable reactive polymer has one or more functional groups that are attached to the inner surface. The one or more functional groups provide for cross-linking of the coating to the inner surface, e.g., thermal cross-linking and / or radical cross-linking.

[0053] In some embodiments, the solution for exchanging anions includes a salt solution. Exchangeable anions in the salt solution include, but are not limited to, hexafluorophosphate (PF6“), tetrafluoroborate (BET), bis(trifluoromethylsulfonyl)imide, i.e., bistriflimide (NTfz, [(CF3SO2)2N]-), trifluoromethanesulfonate, i.e., triflate (OSChCF’-. dicyanamide (C2N3)-, dimethylphosphate (C2H6O4P)-, acetate (CH .COO)-, bisulfate (HSCU)-, and ethyl sulfate (CFECFEOSCF)-. The salt solution is directed into the chromatography column to facilitate ion exchange between the anionic end of the ionic functional groups and the anion in the salt solution.

[0054] Once the anions are exchanged, the separation performance of the chromatography column is re-evaluated with the exchanged anion. Re-evaluating can include injecting a sample onto the column and determining changes in one or more of the previously evaluated criteria, i.e., peak height, peak area, and / or peak shape.Attorney Docket No.: A2208-7006WO

[0055] EXAMPLES

[0056] The function and advantages of these and other embodiments can be better understood from the following examples. These examples are intended to be illustrative in nature and are not considered to be in any way limiting the scope of the invention.

[0057] Example 1

[0058] In this example, methods for preparing a GC column with an immobilized polar IL-siloxane hybrid stationary phase are described. This example explored two different routes for preparing the GC column. The first route was an “off column” method where the coating for the column was prepared outside of the column and then applied to the inner surface. The second route was an “on column” route where the coating components were applied sequentially within the column.

[0059] In the “off column” method, a hybrid IL-siloxane polymer was first synthesized containing cross -linkable silicon-vinyl groups separate from the ionic liquid groups. This soluble hybrid polymer was coated inside a capillary column using the static coating procedure. Once coated, the hybrid polymer was immobilized inside thermal or radical induced crosslinking of the vinyl groups. The “off column” method is illustrated in FIG. 3 A. As illustrated in FIG. 3A, a cross-linkable reactive polymer was synthesized containing one or more reactive functional groups (-R) coordinated to a PDMS backbone and one or more functional groups (-X) that are cross -linkable. The one or more reactive functional groups (-R) were converted into ionic functional groups by reaction with nucleophilic reagents. The cationic end of the ionic functional groups were covalently bonded to the PDMS backbone. The anionic end of the ionic functional groups were exchanged to a different anion by the addition of a salt solution having the preferred anion. The anion of the anionic end of the ionic functional groups were exchanged to increase the thermal stability of the coating within the GC column and to adjust the chromatographic characteristics. Once the preferred anion was included in the coating, the coating was directed into the GC column and thermally treated to cross-link one or more functional groups (-X) to the inner surface of the fused silica column.

[0060] In the “on column” method, illustrated in FIG. 3B, a cross -linkable reactive polymer was synthesized which contained cross -linkable vinyl groups and one or more reactive functional groups. The cross -linkable reactive polymer was coated and immobilized inside a GC capillary column by the cross-linkable groups (-X). As the cross-linkable reactive polymer was apolar, standard deactivation procedures were used to minimize the influence ofAttorney Docket No.: A2208-7006WO

[0061] the underlying fused silica. This deactivation allowed for an even spreading of the crosslinkable reactive polymer on the inner surface of the column. Once immobilized, the one or more reactive functional groups (-R) were converted into ionic functional groups by reaction with a nucleophilic reagent. The immobilized cross -linkable reactive polymer was rinsed with suitable liquids to purify the converted immobilized layer and remove excess reagents and unwanted side products. The cationic end of the ionic functional groups were covalently bonded to the PDMS backbone. The anionic end of the ionic functional groups were exchanged to a different anion by the addition of a salt solution having the preferred anion. The anion of the anionic end of the ionic functional groups were exchanged to increase the thermal stability of the coating within the GC column and to adjust the chromatographic characteristics.

[0062] Example 2

[0063] In this example, an evaluation of the polarity of the coatings disclosed herein is described. McReynolds constant values provide a systematic approach to ranking GC stationary phases by polarity and simplify the task of cross-comparing phases to determine whether they are equivalent. To determine the McReynolds index (RI), characteristic probes are used which are eluted in between reference n-alkancs. Based on the elution relative to neighboring alkanes, a McReynolds index value can be calculated based on their retention times. FIG. 4 illustrates the mathematical formalism for determining the McReynolds index using probe compounds including benzene, butanol, 2-pentanone, nitropropane, and pyridine. A larger McReynolds number for the probes generally indicates an increased polarity stationary phase. However, depending on the chemical structure of a stationary phase, the relative shift of McReynolds numbers with polarity is often not linear. Specific molecular interactions between the selected probes and the stationary phase may result in probe specific shifts as a function of polarity.

[0064] Using the McReynolds constants for the selected probes, one can further

[0065] simplify the polarity index of a stationary phase by using the CP-index number. The CP-index number has a value of “0” for the most apolar phase, i.e., squalane) and “100” for the most polar phase, i.e., dicyanoalkylsilicone. The calculation of the CP-index number, of which the formalism is illustrated in FIG. 5, expresses the polarity of an unknown phase as a single number on a polarity scale of 0-100. As the polarity of the stationary phase increases, the CP-index increases, thus providing an indication of the overall polarity of developed stationary phases.Attorney Docket No.: A2208-7006WO

[0066] Example 3

[0067] In this example, the production and characterization of a GC column having a coating as disclosed herein is described.

[0068] The cross-linkable reactive polymer was synthesized by the acid-catalyzed hydrolysis of the corresponding alkoxysilanes illustrated in FIG. 6A. More specifically, a low molecular weight pre-polymer was made and isolated. This pre-polymer was then converted into a high molecular weight polymer by triflic acid catalysis. The cross -linkable reactive polymer was purified by removal of the triflic acid catalyst by solvent extraction. The composition of the final cross-linkable reactive polymer was dependent on the stoichiometric ratio of the starting alkoxysilanes.

[0069] The formation of the ionic functional groups from the one or more reactive functional groups of the cross -linkable reactive polymer was performed according to the reaction illustrated in FIG. 6B. As illustrated in FIG. 6B, the reactive chloropropyl groups in the cross-linkable reactive polymer was reacted with 1 -methylimidazole, which resulted in the [imidazole]+[Cl] “ ionic group. The chloride anion was known to lack thermal stability due to isolation of the negative charge. To provide for a more homogenous charge distribution in the anionic end of the ionic functional groups, the chloride anion was exchanged for the bis(trifluoromethylsulfonyl)imide ion, i.e., bistriflimide (NTfz, [(CFaSOs N]-) following the reaction illustrated in FIG. 6C. Successful formation of the hybrid IF-siloxane coating with bistriflimide was evidenced by the FT-IR spectra illustrated in FIG. 7 compared against reference spectra for neat PDMS and neat bistriflimide. As illustrated in FIG. 7, the IR frequencies corresponding to both PDMS and bistriflimide were identified in the IR spectrum of the hybrid IF-siloxane coating, confirming successful exchange of the chloride ion.

[0070] A GC column with 30 m x 0.25 mm ID x 0.4 pm film thickness was prepared using the hybrid IF-siloxane polymer as the stationary phase. To evaluate the polarity of the as-prepared column, the separation factor a between heptadecane and aniline and the McReynolds constants were measured. The measured McReynolds constants were converted to the CP-index numbers. The results of the determination of the polarity are illustrated in FIG. 8. As illustrated in FIG. 8, the overall polarity of the coating was between 52-57, which is approximately equivalent to the polarity of commercially available GC columns based on polyethylene glycol coatings which have a CP-index between 50-60.

[0071] The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. As used herein, the term “plurality” refers to two or moreAttorney Docket No.: A2208-7006WO

[0072] items or components. The terms “comprising,” “including,” “carrying,” “having,” “containing,” and “involving,” whether in the written description or the claims and the like, are open-ended terms, i.e., to mean “including but not limited to.” Thus, the use of such terms is meant to encompass the items listed thereafter, and equivalents thereof, as well as additional items. Only the transitional phrases “consisting of’ and “consisting essentially of,” are closed or semi-closed transitional phrases, respectively, with respect to the claims. Use of ordinal terms such as “first,” “second,” “third,” and the like in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

[0073] Having thus described several aspects of at least one embodiment, it is to be appreciated various alterations, modifications, and improvements will readily occur to those skilled in the art. Any feature described in any embodiment may be included in or substituted for any feature of any other embodiment. Such alterations, modifications, and improvements are intended to be part of this disclosure and are intended to be within the scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.

[0074] Those skilled in the art should appreciate that the parameters and configurations described herein are exemplary and that actual parameters and / or configurations will depend on the specific application in which the disclosed methods and materials are used. Those skilled in the art should also recognize or be able to ascertain, using no more than routine experimentation, equivalents to the specific embodiments disclosed.

Claims

Attorney Docket No.: A2208-7006WOCLAIMSWhat is claimed is:

1. A chromatography column comprising a coating on an inner surface, the coating comprising a cross-linkable reactive polymer and ionic functional groups, the cross -linkable reactive polymer having one or more functional groups that are attached to the inner surface.

2. The column of claim 1, wherein the cross -linkable reactive polymer comprises a siloxane backbone.

3. The column of claim 2, wherein the siloxane comprises poly dimethylsiloxane.

4. The column of claim 3, wherein the one or more functional groups are covalently bonded to the polydimethylsiloxane backbone.

5. The column of claim 1, wherein the one or more functional groups include vinyl, tolyl, peroxides, acrylates, hydrogen, methacrylate, epoxy, hydroxyl, thiol, and amine.

6. The column of claim 5, wherein the one or more functional groups are cross-linked to the inner surface.

7. The column of claim 1, wherein the cross -linkable reactive polymer comprises one or more reactive functional groups selected from haloalkyl, haloalkenyl, halophenyl, and haloalkylphenyl.

8. The column of claim 7, wherein the one or more reactive functional groups react to form the ionic functional groups that are covalently bonded on the cross -linkable reactive polymer.

9. The column of claim 8, wherein the one or more reactive functional groups react with a nucleophilic reagent to form the ionic functional groups.

10. The column of claim 9, wherein the nucleophilic reagent comprises substituted or unsubstituted amines, substituted or unsubstituted phosphines, and thioethers.Attorney Docket No.: A2208-7006WO11. The column of claim 9, wherein a cationic end of the ionic functional groups are covalently bonded to the cross -linkable reactive polymer.

12. The column of claim 11, wherein an anionic end of the ionic functional groups is exchangeable.

13. The column of claim 12, wherein exchange of the anionic end of the ionic functional groups adjusts one or more of column selectivity, column thermal stability, and column inertness.

14. A chromatography system, comprising:an enclosure comprising:a chromatography column comprising a coating on an inner surface, the coating comprising a cross-linkable reactive polymer and ionic functional groups, the cross-linkable reactive polymer having one or more functional groups that are attached to the inner surface;a sample inlet connectable to a first end of the chromatography column; and a detector connectable to a second end of the chromatography column.

15. The system of claim 14, wherein the one or more functional groups are cross-linked to the inner surface.

16. The system of claim 14, wherein the ionic functional groups comprise a cationic end and an anionic end.

17. The system of claim 16, wherein the anionic end of the ionic functional groups is exchangeable to increase thermal stability of the coating.

18. The system of claim 16, wherein the anionic end of the ionic functional groups is exchangeable to adjust one or more of column selectivity, column thermal stability, and column inertness of the coating on the chromatography column.Attorney Docket No.: A2208-7006WO19. The system of claim 17, wherein the exchange of the anionic end of the ionic functional groups results from contact of the coating with a solution comprising an anion different than the anionic end.

20. The system of claim 19, wherein exchangeable anions include hexafluorophosphate, tetrafluoroborate, bis(trifluoromethylsulfonyl)imide, trifluoromethanesulfonate, dicyanamide, dimethylphosphate, acetate, bisulfate, and ethyl sulfate.

21. A method of adjusting a selectivity of a chromatography column, comprising:performing a separation of a sample using the column, the chromatography column comprising a coating on an inner surface, the coating comprising a cross-linkable reactive polymer and ionic functional groups comprising a cationic end and an anionic end;evaluating a separation performance of the chromatography column; and contacting the coating with a solution comprising an anion different than the anionic end to exchange the anions in the coating.

22. The method of claim 21, wherein exchanging the anions in the coating does not remove the coating from the inner surface.

23. The method of claim 21, wherein the cross -linkable reactive polymer has one or more functional groups that are attached to the inner surface.

24. The method of claim 21, wherein the solution for exchanging anions comprises an ionic liquid solution.

25. The method of claim 24, wherein the ionic liquid solution comprises hexafluorophosphate, tetrafluoroborate, bis(trifluoromethylsulfonyl)imide, trifluoromethanesulfonate, dicyanamide, dimethylphosphate, acetate, bisulfate, or ethyl sulfate.

26. The method of claim 25, further comprising re-evaluating a separation performance of the chromatography column with the exchanged anion.

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