Alkyl functionalized porous silica liquid chromatographic stationary phases and solid phase extraction sorbents

Abstract

A chromatographic stationary phase or solid phase extraction (SPE) sorbent are sol-gel metal oxide particles comprising metal oxide network units with organic functionality bonded to the metal of the metal oxide and possess a higher performance or capacity than that of conventional ligand coated silica particles. The organic functionality is distributed throughout the metal oxide particle and wherein the mole percent of metals of the metal oxides with bonded organic functionality is in excess of nine mole percent of the particle. The particles are prepared from sol-gel processing employing an acid catalyst or an acid catalyst followed by a base catalyst to metal oxide precursors, at least nine mole percent of which have organic functionality. The particles are processed from a sol-gel condensation product into a size depending on the intended use.

Claims

1. A chromatographic stationary phase or solid phase extraction (SPE) sorbent, comprising highly porous sol-gel metal oxide particles comprising metal oxide network units with organic functionality bonded to at least some metal atoms of the metal oxide network, wherein the particles are prepared by a sequential acid catalyzed then base catalyzed sol-gel process to impart a BET surface area is 650 m.sup.2/g and a pore width of 30 , where the organic functionality is selected from alkyl, substituted alkyl, aryl, or any combination thereof, wherein organic functionality is distributed throughout the particles; and wherein the mole percent of metal atoms of the metal oxides with bonded organic functionality is 9 to 100 mole percent.

2. The chromatographic stationary phase or SPE sorbent according to claim 1, wherein the metal oxides are oxides of silicon, titanium, aluminum, zirconium, germanium, barium, gallium, indium, thallium, vanadium, cobalt, nickel, chromium, copper, iron, zinc, boron or any mixture thereof and where the organic functionalities are: linear or branched C1 to C24 alkyl that is unsubstituted or substituted with phenyl, amino, alkylamino, hydroxyl, alkoxyl, arylamino, cyano, fluoro, phenyl, cyclodextrin, crown ether, cryptand, calixarene, or any derivative thereof; or aryl that is unsubstituted or substituted with phenyl, amino, alkylamino, hydroxyl, alkoxyl, arylamino, cyano, fluoro, phenyl, cyclodextrin, crown ether, cryptand, calixarene, or any derivative thereof.

3. The chromatographic stationary phase or SPE sorbent according to claim 1, wherein the metal oxide is silicon oxide.

4. The chromatographic stationary phase or SPE sorbent according to claim 1, wherein the organic functionality is selected from methyl, octyl, octadecyl, phenyl, 2-phenylethyl, 3-aminopropyl, 3-(2-aminoethylamino)propyl, 3-methylaminopropyl, 3-phenylaminopropyl, and 3-(2-benzylaminoethyl)propyl.

5. A method of preparing a chromatographic stationary phase or SPE sorbent according to claim 1, comprising: providing a multiplicity of at least one first metal oxide precursor, wherein at least 9 percent of the metal oxide precursors have one or two organic functionalities bonded to the metal oxide precursor; mixing at least a portion of the metal oxide precursors with a solvent or solvent mixture and an acid and water to form a sol; optionally adding at least one second metal oxide precursor having at least one organic functionality that is the same or different than the organic functionalities of the first metal oxide precursors to the sol; adding a base to the sol; holding the sol until the sol converts into a gel; crushing or grinding the gel to form sol-gel metal oxide particles that comprise the chromatographic stationary phase or SPE sorbent.

6. The method of claim 5, wherein the metal oxides precursors are of the structure MR.sup.1R.sup.2R.sup.3R.sup.4 where M is silicon, titanium, aluminum, zirconium, germanium, barium, gallium, indium, thallium, vanadium, cobalt, nickel, chromium, copper, iron, zinc, boron or any mixture thereof where R.sup.1 and R.sup.2 are hydrogen, alkoxy, hydroxy, halide, or dialkylamino, R.sup.3 and R.sup.4 are optionally hydrogen, alkoxy, hydroxy, halide, or dialkylamino, which are lost on hydrolysis to form hydroxyl groups, a majority of which condense to form the metal oxide, and at least some of R.sup.3 and R.sup.4, independently, are absent or are substituted or unsubstituted linear or branched C1 to C24 alkyl, substituted or unsubstituted aryl wherein the substituent is phenyl, amino, alkylamino, hydroxyl, alkoxyl, arylamino, cyano, fluoro, phenyl, cyclodextrin, crown ether, cryptand, calixarene, or any derivative thereof.

7. The method of claim 5, wherein the acid is selected from hydrochloric acid, trifluoracetic acid, acetic acid, hydrofluoric acid, and oxalic acid.

8. The method of claim 5, wherein the base is selected from sodium hydroxide, potassium hydroxide, ammonium hydroxide, or an aminoalkylsilane.

9. The method of claim 5, wherein the solvent is a C1 to C3 alcohol or a mixture of a C1 to C3 alcohol and methylene chloride.

10. The method of claim 5, wherein the crushing or grinding is to a particle size of 40 to 50 microns for SPE sorbent and 2 to 5 microns for chromatography stationary phases.

11. A method of performing solid phase extraction, comprising placing a device comprising the SPE sorbent according to claim 1 in an environment containing a compound to remove from the environment.

12. The method of claim 11, wherein the device is a container that retains the SPE sorbent and allows the contact with the environment while being retained within the container.

13. A chromatography column, comprising a column packing comprising the chromatographic stationary phase according to claim 1.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows a bar chart of the degree of absorption of various analytes by a sol-gel C18 sorbent, according to an embodiment of the invention.

(2) FIG. 2 shows the structure and provides the log K.sub.ow of the analytes of FIG. 1.

(3) FIG. 3 shows an idealized reaction scheme for the hydrolysis and condensation to a sol-gel C18 sorbent, according to an embodiment of the invention, where an acid hydrolysis of tetraalkoxy and C18 trialkoxy silanes is followed by acid condensation of the silanols formed upon hydrolysis.

(4) FIG. 4 shows an idealized reaction scheme for the hydrolysis and condensation to a sol-gel C18 sorbent, according to an embodiment of the invention, where an acid hydrolysis of tetraalkoxy and C18 trialkoxy silanes is followed by base condensation of the silanols formed upon hydrolysis.

(5) FIG. 5 shows an idealized reaction scheme for the hydrolysis and condensation to a sol-gel C18 sorbent, according to an embodiment of the invention, where an acid hydrolysis of C1 and C18 trialkoxy silanes is followed by base condensation of the silanols formed upon hydrolysis.

(6) FIG. 6 shows an idealized reaction scheme for the hydrolysis and condensation to a sol-gel C18 sorbent, according to an embodiment of the invention, where an acid hydrolysis of C18 trialkoxy silanes is followed by base condensation of the silanols formed upon hydrolysis.

(7) FIG. 7 shows an idealized reaction scheme for the hydrolysis and condensation to a sol-gel C18 sorbent, according to an embodiment of the invention, where an acid hydrolysis of tetraalkoxy and C1 and C18 trialkoxy silanes is followed by base condensation of the silanols formed upon hydrolysis.

(8) FIG. 8 shows an idealized reaction scheme for the hydrolysis and condensation to a sol-gel C18 sorbent, according to an embodiment of the invention, where an acid hydrolysis of tetraalkoxy and phenyl and C18 trialkoxy silanes is followed by base condensation of the silanols formed upon hydrolysis.

(9) FIG. 9 shows an idealized reaction scheme for the hydrolysis and condensation to a sol-gel C18 sorbent, according to an embodiment of the invention, where an acid hydrolysis of tetraalkoxy and 2-phenylethyl and C18 trialkoxy silanes is followed by base condensation of the silanols formed upon hydrolysis.

(10) FIG. 10 shows an idealized reaction scheme for the hydrolysis and condensation to a sol-gel C18 sorbent, according to an embodiment of the invention, where an acid hydrolysis of tetraalkoxy and 3-aminopropyl and C18 trialkoxy silanes is followed by base condensation of the silanols formed upon hydrolysis.

(11) FIG. 11 shows an idealized reaction scheme for the hydrolysis and condensation to a sol-gel C18 sorbent, according to an embodiment of the invention, where an acid hydrolysis of tetraalkoxy and phenyl, 3-aminopropyl, and C18 trialkoxy is followed by base condensation of the silanols formed upon hydrolysis.

(12) FIG. 12 shows an idealized reaction scheme for the hydrolysis and condensation to a sol-gel C18 sorbent, according to an embodiment of the invention, where an acid hydrolysis of tetraalkoxy and 3-(2 aminoethylamino)propyl and C18 trialkoxy silanes is followed by base condensation of the silanols formed upon hydrolysis.

(13) FIG. 13 shows an idealized reaction scheme for the hydrolysis and condensation to a sol-gel C18 sorbent, according to an embodiment of the invention, where an acid hydrolysis of tetraalkoxy and 3-(methylamino)propyl and C18 trialkoxy silanes is followed by base condensation of the silanols formed upon hydrolysis.

(14) FIG. 14 shows an idealized reaction scheme for the hydrolysis and condensation to a sol-gel C18 sorbent, according to an embodiment of the invention, where an acid hydrolysis of tetraalkoxy and 3-(phenylamino)propyl and C18 trialkoxy silanes is followed by base condensation of the silanols formed upon hydrolysis.

(15) FIG. 15 shows an idealized reaction scheme for the hydrolysis and condensation to a sol-gel C18 sorbent, according to an embodiment of the invention, where an acid hydrolysis of tetraalkoxy and 3-(2-(2-phenylethyl)aminoethyl)propyl and C18 trialkoxy silanes is followed by base condensation of the silanols formed upon hydrolysis.

(16) FIG. 16 shows an idealized reaction scheme for the hydrolysis and condensation to a sol-gel C18 sorbent, according to an embodiment of the invention, where an acid hydrolysis of tetraalkoxy and 3-aminopropyl and C18 trialkoxy silanes is followed by base condensation of the silanols formed upon hydrolysis where additional 3-aminopropyltrimethoxy silane is used as the base.

DETAILED DISCLOSURE

(17) Embodiments of the invention are directed to sol-gel synthesis of alkyl functionalized (e.g., C4, C8, C12, C18) high performance liquid chromatographic (HPLC) stationary phases and solid phase extraction (SPE) sorbents. The synthetic method employs a tetrafunctional silane and a trifunctional silane containing a sorbent functionality, for example, tetraalkoxy silane and an alkyltrialkoxy silane or their equivalents in presence of either an acid catalyst, an acid catalyst followed by a base catalyst, or a base catalyst. Analysis by a reverse phase chromatography method or sampling by a solid phase extraction method where matrix pH adjustment allows removal and separation of highly acidic and basic compounds in the compounds' neutral state. The sol-gel synthesis method integrates the alkyltrialkoxy silane and tetralkoxysilane into a three dimensional polymeric network via hydrolysis followed by polycondensation, to yield a chemically and structurally more stable highly porous hybrid inorganic-inorganic material. Due to the high porosity and extremely high surface area, the HPLC stationary phase and SPE sorbents offer more analyte-alkyl functional group interactions per unit mass of the stationary phases/SPE sorbents; consequently minimizing the required mass of the stationary phases/SPE sorbents to achieve target chromatographic separation or extraction efficiency. Additionally, consumption of organic solvents in chromatographic separation and sample preparation is significantly reduced.

(18) The method according to embodiments of the invention is a sol-gel synthesis approaches to create various alkyl/aryl functionalized, including, but not limited to, C.sub.6H.sub.5, C.sub.4H.sub.9, C.sub.8H.sub.17, C.sub.12H.sub.25, C.sub.18H.sub.37 alkyl substituted high performance liquid chromatographic (HPLC) stationary phases and solid phase extraction (SPE) sorbents using a trialkoxy silane and an alkyl trialkoxysilane or aryl trialkoxysilane in presence of an acid catalyst, an acid catalyst followed by a base catalyst, or a base catalyst. Optionally, a tetraalkoxy silane can be included or used without the trialkoxysilane. The alkoxy groups can be methoxy, ethoxy, propoxy, or any mixture thereof. The resulting particulate gel is a three dimensional polymeric network that is highly porous, and is chemically and structurally stable. Due to the high porosity and very high surface area, the HPLC stationary phase and SPE sorbents that comprises these gels offer more analyte-alkyl or analyte-aryl functional group interactions per unit mass of the stationary phases or SPE sorbents than is presently available. The high performance sol-gel material can be an SPE sorbent with a 40-50 m particle size, a conventional high performance liquid chromatographic (HPLC) stationary phases with a 5 m particle size and ultra-performance liquid chromatographic (UPLC) stationary phases with a 2 m particle size.

(19) This SPE and chromatographic stationary phases using the sol-gel materials according to embodiments of the invention, eliminate the use of a silica substrate as the host matrix to hold different alkyl/aryl pendant groups that grafted on the silica substrate's surface via silane surface modification strategies. This sol-gel material provides a superior alternative to the conventional silica coated approach for reverse phase HPLC stationary phases and SPE sorbents, as the sol-gel materials integrate the alkyl/aryl pendant group to a sol-gel network.

(20) In other embodiments of the invention the sol-gel synthesis can be carried out with one or more a variety of different precursors of the structure MR.sup.1R.sup.2R.sup.3R.sup.4 where M is silicon, titanium, aluminum, zirconium, germanium, barium, gallium, indium, thallium, vanadium, cobalt, nickel, chromium, copper, iron, zinc, boron or any mixture thereof. Two or more of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are hydrogen, alkoxy, hydroxy, halide, or dialkylamino, and the remaining R.sub.1, R.sub.2, R.sub.3 and R.sub.4 independently are, depending on M, absent or are alkyl, arylene, cyanoalkyl, fluoroalkyl, phenyl, cyanophenyl, biphenyl, cyanobiphenyl, dicyanobiphenyl, cyclodextrin, crown ether, cryptand, calixarene, or any derivative thereof. Depending upon M, the sol-gel synthesis can be uncatalyzed, acid catalyzed, base catalyzed, or an acid and base catalysis can be carried out in a plurality of steps. The metal cations can be chelated by acid. When a plurality of MR.sup.1R.sup.2R.sup.3R.sup.4 precursors are used, the hydrolysis of individual precursors or partial mixtures of precursors can be carried out with or without condensation, where the degree of condensation is short of a gel point, and the hydrolyzed and these uncondensed or partially condensed intermediate hydrolysates can be mixed and the combined hydrolysates condensed to the desired gels. The MR.sup.1R.sup.2R.sup.3R.sup.4 precursors in the mixture can differ by identity of any of M, R.sup.1, R.sup.2, R.sup.3 and/or R.sup.4.

(21) The hydrolysis and condensation can be catalyzed by the addition of an acid or a base. An acid or base catalyst is not necessary when one or more of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 of any precursor in the mixture is a Cl, Br, I, or dialkylamino group. An acid catalyst can be a Bronsted acid or a Lewis acid and the base can be a Bronsted base or a Lewis base. The acid can be a strong acid or a weak acid and the base can be a strong base or a weak base. Acids can be chosen from organic acids or inorganic acids and bases can be chosen from organic bases or inorganic bases. Acids that can be used include, but are not limited to, acetic acid, trifluoroacetic acid, trifluoromethylsulfonic acid, benzoic acid, oxalic acid, carbonic acid, boric acid, sulfuric acid, hydrochloric acid, hydrobromic acid, hydroionic acid, chloric acid, perchloric acid, phosphoric acid, ferric chloride, aluminum chloride, stannous chloride, copper chloride, or zinc chloride. Bases that can be used include, but are not limited to, aluminum hydroxide, ammonium hydroxide, lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide, alkyl amine, dialkyl amine, trialkyl amine, pyridine, or aniline.

(22) The preparation of the sol-gel synthesis can be carried out in a solvent. The solvent can be any solvent that can be removed to a large degree. The solvent can be, but is not limited to, methanol, ethanol, n-propanol, i-propanol, diethyl ether, ethyl acetate, tetrahydrofuran, acetone, methylene chloride, chloroform, acetonitrile, dimethylsulfoxide, or any compatible mixture thereof. The solvent should be one that can be removed as a volatile or washed from the sol-gel material by a volatile solvent.

(23) According to an embodiment of the invention, a sol-gel hybrid inorganic-organic material is a reverse phase HPLC stationary phases in a HPLC column. Due to its high porosity and large surface area a superior chromatographic selectivity results. The solvent stability for reverse phase HPLC stationary phases and SPE reverse phase sorbents is particularly advantageous.

(24) The sol-gel hybrid inorganic-organic material does not employ a silica substrate as the host matrix for alkyl/aryl pendant groups grafted on the silica substrate as a surface bound functionality. The sol-gel preparation allows the integration of alkyl/aryl pendant group in a porous silica network to result: in a higher surface area; a superior hydrolytic stability; extended pH stability (pH 1-12) with higher carbon loading; lower back-pressure; higher chromatographic separation power with a substantially high number of theoretical plates (N) pre equivalent length of chromatographic column; higher extraction efficiency; higher sample capacity: lower consumption of organic solvents for chromatographic separation/SPE elution; and the elimination of solvent evaporation and sample reconstitution when used as SPE sorbents. For example, an exemplary sol-gel C18 material when employed as a SPE sorbent is superior to commercially available C18 SPE sorbents, particularly with respect to the Brunauer-Emmett-Teller (BET) adsorption isotherm of the sol-gel sorbents and the commercial C18, as shown in FIG. 1, for the compounds tested provided in FIG. 2. A comparison of the sorbent structures from a sol-gel process relative to commercial sorbent using coated silica particles is given in Table 1, below; for sol-gel sorbents formed as in compositions 1 and 2 described below.

(25) TABLE-US-00001 TABLE 1 BET surface area, pore volume, and average pore width of sol-gel C18 and commercial C18 SPE sorbents BET Surface Pore Volume Average Pore Sorbent Area in m.sup.2/g in cm.sup.3/g width in Commercial C18 SPE 345.7607 0.724864 83.6574 Sol-gel C18 (acid 0.3617 0.004011 443.59 catalyzed) Sol-gel C18 (acid- 649.1233 0.436021 26.9 base catalyzed)

Methods and Materials

(26) Composition 1: Sol-Gel C18 Particles Using Acid Catalysis

(27) As conceptually illustrated in FIG. 3, a 3.08 molar ratio of tetramethoxysilane (2000 L) and n-octadecyl trimethoxysilane (2000 L) were combined in in methanol (2000 L). To the homogeneous solution was added a solution of 3960 L of trifluoroacetic acid and 40 L of water with vortex mixing. A bed of white sol-gel C18 particles precipitated and the bed was held at 50 C. for two days. The bed of adhering particles was ground and washed with methylene chloride. The ground particles were screened to isolate a narrow particle size distribution of C18 particles.

(28) Composition 2: Sol-Gel C18 Particles (Acid Catalyzed)

(29) As conceptually illustrated in FIG. 3, tetramethoxysilane (1000 L) and n-octadecyl trimethoxysilane (300 L) were combined in in 6000 L of a 1:1 by volume mixture of methylene chloride and methanol. To the homogeneous solution was added 470 L of 0.1 M hydrochloric acid with vortex mixing. The acid solution was stirred at 50 C. for 12 hours. A bed of white sol-gel C18 particles precipitated and the bed was held at 50 C. for two days. The bed of adhering particles was ground and washed with methylene chloride. The ground particles were screened to isolate a narrow particle size distribution of C18 particles.

(30) Composition 3: Sol-Gel C18 Particles (Acid Catalyzed Followed by Base Catalyzed)

(31) As conceptually illustrated in FIG. 4, tetramethoxysilane (400 L) and n-octadecyl trimethoxysilane (120 L) were combined in in 3040 L of isopropanol. To the homogeneous solution was added 188 L of 0.1 M hydrochloric acid with vortex mixing. The acid solution was stirred at 50 C. for 12 hours. A bed of white sol-gel C18 particles precipitated and the bed was held at 50 C. for 2-12 hours. To the hydrolyzed mixture was added 100 L of 1 M ammonium hydroxide in isopropanol. A transparent monolithic bed of a sol-gel C18 network was held at 50 C. for two days. The bed was crushed, ground and washed with methylene chloride. The ground particles were screened to isolate a narrow particle size distribution of C18 particles.

(32) Composition 4: Sol-Gel C18 Particles (Acid Catalyzed Followed by Base Catalyzed)

(33) As conceptually illustrated in FIG. 5, trimethoxymethylsilane (400 L) and n-octadecyl trimethoxysilane (200 L) were combined in in 2000 L of isopropanol. To the homogeneous solution was added 100 L of 0.1 M trifluoroacetic acid with vortex mixing. The acid solution was held at 50 C. for 12 hours. To the hydrolyzed mixture was added 100 L of 1 M ammonium hydroxide in isopropanol. A transparent monolithic bed of a sol-gel C18 network was held at 50 C. for two days. The bed was crushed, ground and washed with methylene chloride. The ground particles were screened to isolate a narrow particle size distribution of C18 particles.

(34) Composition 5: Sol-Gel C18 Particles (Acid Catalyzed Followed by Base Catalyzed)

(35) As conceptually illustrated in FIG. 6, n-octadecyl trimethoxysilane (200 L) was dissolved in 6000 L of isopropanol. To the homogeneous solution was added 470 L of 0.1 M hydrochloric with vortex mixing. The acid solution was held at 50 C. for 12 hours. To the hydrolyzed mixture was added 100 L of 1 M ammonium hydroxide in isopropanol. A transparent monolithic bed of a sol-gel C18 network was held at 50 C. for two days. The bed was crushed, ground and washed with methylene chloride. The ground particles were screened to isolate a narrow particle size distribution of C18 particles.

(36) Composition 6: Sol-Gel C18 Particles (Acid Catalyzed Followed by Base Catalyzed)

(37) As conceptually illustrated in FIG. 7, tetramethoxysilane (500 L), trimethoxymethylsilane (500 L), and n-octadecyl trimethoxysilane (300 L) were combined in in 6000 L of a 1:1 by volume mixture of methylene chloride and methanol. To the homogeneous solution was added 470 L of 0.1 M hydrochloric acid with vortex mixing. The acid solution was held at 50 C. for 12 hours. To the hydrolyzed mixture was added 250 L of 1 M ammonium hydroxide in isopropanol. A transparent monolithic bed of a sol-gel C18 network was held at 50 C. for two days. The bed was crushed, ground and washed with methylene chloride. The ground particles were screened to isolate a narrow particle size distribution of C18 particles.

(38) Composition 7: Sol-Gel C18 Particles (Acid Catalyzed Followed by Base Catalyzed)

(39) As conceptually illustrated in FIG. 8, tetramethoxysilane (500 L), trimethoxyphenylsilane (320 L), and n-octadecyl trimethoxysilane (500 L) were combined in in 7600 L of a 1:1 by volume mixture of methylene chloride and methanol. To the homogeneous solution was added 470 L of 0.1 M acetic acid with vortex mixing. The acid solution was held at 50 C. for 12 hours. To the hydrolyzed mixture was added 300 L of 1 M ammonium hydroxide in isopropanol. A transparent monolithic bed of a sol-gel C18 network was held at 50 C. for two days. The bed was crushed, ground and washed with methylene chloride. The ground particles were screened to isolate a narrow particle size distribution of C18 particles.

(40) Composition 8: Sol-Gel C18 Particles (Acid Catalyzed Followed by Base Catalyzed)

(41) As conceptually illustrated in FIG. 9, tetramethoxysilane (500 L), trimethoxy-2-phenylethylsilane (320 L), and n-octadecyl trimethoxysilane (500 L) were combined in in 7600 L of a 1:1 by volume mixture of methylene chloride and methanol. To the homogeneous solution was added 470 L of 0.1 M acetic acid with vortex mixing. The acid solution was held at 50 C. for 12 hours. To the hydrolyzed mixture was added 300 L of 1 M ammonium hydroxide in isopropanol. A transparent monolithic bed of a sol-gel C18 network was held at 50 C. for two days. The bed was crushed, ground and washed with methylene chloride. The ground particles were screened to isolate a narrow particle size distribution of C18 particles.

(42) Composition 9: Sol-Gel C18 Particles (Acid Catalyzed Followed by Base Catalyzed)

(43) As conceptually illustrated in FIG. 10, tetramethoxysilane (1000 L), and n-octadecyl trimethoxysilane (300 L) were combined in in 7600 L of isopropanol. To the homogeneous solution was added 470 L of 0.1 M hydrochloric acid with vortex mixing. The acid solution was held at 50 C. for 12 hours. 3-Aminopropyl)trimethoxysilane (320 L) was added to the mixture and held at 50 C. for 1 hour. To the hydrolyzed mixture was added 300 L of 1 M ammonium hydroxide in isopropanol. A transparent monolithic bed of a sol-gel C18 network was held at 50 C. for two days. The bed was crushed, ground and washed with methylene chloride. The ground particles were screened to isolate a narrow particle size distribution of C18 particles.

(44) Composition 10: Sol-Gel C18 Particles (Acid Catalyzed Followed by Base Catalyzed)

(45) As conceptually illustrated in FIG. 11, tetramethoxysilane (1000 L), and n-octadecyl trimethoxysilane (300 L) were combined in in 7600 L of isopropanol. To the homogeneous solution was added 470 L of 0.1 M hydrochloric acid with vortex mixing. The acid solution was held at 50 C. for 12 hours. (3-Aminopropyl)trimethoxysilane (320 L) and trimethoxyphenylsilane (330 L) were added to the mixture and held at 50 C. for 1 hour. To the hydrolyzed mixture was added 300 L of 1 M ammonium hydroxide in isopropanol. A transparent monolithic bed of a sol-gel C18 network was held at 50 C. for two days. The bed was crushed, ground and washed with methylene chloride. The ground particles were screened to isolate a narrow particle size distribution of C18 particles.

(46) Composition 11: Sol-Gel C18 Particles (Acid Catalyzed Followed by Base Catalyzed)

(47) As conceptually illustrated in FIG. 12, tetramethoxysilane (1000 L), and n-octadecyl trimethoxysilane (300 L) were combined in in 7600 L of isopropanol. To the homogeneous solution was added 470 L of 0.1 M hydrochloric acid with vortex mixing. The acid solution was held at 50 C. for 12 hours. N-[3-(trimethoxysilyl)propyl]ethylene diamine (320 L) were added to the mixture and held at 50 C. for 1 hour. To the hydrolyzed mixture was added 300 L of 1 M ammonium hydroxide in isopropanol. A transparent monolithic bed of a sol-gel C18 network was held at 50 C. for two days. The bed was crushed, ground and washed with methylene chloride. The ground particles were screened to isolate a narrow particle size distribution of C18 particles.

(48) Composition 12: Sol-Gel C18 Particles (Acid Catalyzed Followed by Base Catalyzed)

(49) As conceptually illustrated in FIG. 13, tetramethoxysilane (1000 L), and n-octadecyl trimethoxysilane (300 L) were combined in in 7600 L of isopropanol. To the homogeneous solution was added 470 L of 0.1 M hydrochloric acid with vortex mixing. The acid solution was held at 50 C. for 12 hours. Triethoxy[3-methylamino)propyl]silane (320 L) were added to the mixture and held at 50 C. for 1 hour. To the hydrolyzed mixture was added 300 L of 1 M ammonium hydroxide in isopropanol. A transparent monolithic bed of a sol-gel C18 network was held at 50 C. for two days. The bed was crushed, ground and washed with methylene chloride. The ground particles were screened to isolate a narrow particle size distribution of C18 particles.

(50) Composition 13: Sol-Gel C18 Particles (Acid Catalyzed Followed by Base Catalyzed)

(51) As conceptually illustrated in FIG. 14, tetramethoxysilane (1000 L), and n-octadecyl trimethoxysilane (300 L) were combined in in 7600 L of isopropanol. To the homogeneous solution was added 470 L of 0.1 M hydrochloric acid with vortex mixing. The acid solution was held at 50 C. for 12 hours. N-(2-N-Phenylaminoethyl)-3-aminopropylsilane (320 L) was added to the mixture and held at 50 C. for 1 hour. To the hydrolyzed mixture was added 300 L of 1 M ammonium hydroxide in isopropanol. A transparent monolithic bed of a sol-gel C18 network was held at 50 C. for two days. The bed was crushed, ground and washed with methylene chloride. The ground particles were screened to isolate a narrow particle size distribution of C18 particles.

(52) Composition 14: Sol-Gel C18 Particles (Acid Catalyzed Followed by Base Catalyzed)

(53) As conceptually illustrated in FIG. 15, tetramethoxysilane (1000 L), and n-octadecyl trimethoxysilane (300 L) were combined in in 7600 L of isopropanol. To the homogeneous solution was added 470 L of 0.1 M hydrochloric acid with vortex mixing. The acid solution was held at 50 C. for 12 hours. N-(2-N-benzylaminoethyl)-3-aminopropyltrimethoxysilane (320 L) was added to the mixture and held at 50 C. for 1 hour. To the hydrolyzed mixture was added 300 L of 1 M ammonium hydroxide in isopropanol. A transparent monolithic bed of a sol-gel C18 network was held at 50 C. for two days. The bed was crushed, ground and washed with methylene chloride. The ground particles were screened to isolate a narrow particle size distribution of C18 particles.

(54) Composition 15: Sol-Gel C18 Particles (Acid Catalyzed Followed by Base Catalyzed)

(55) As conceptually illustrated in FIG. 16, tetramethoxysilane (1000 L), and n-octadecyl trimethoxysilane (300 L) were combined in in 7600 L of isopropanol. To the homogeneous solution was added 470 L of 0.1 M hydrochloric acid with vortex mixing. The acid solution was held at 50 C. for 12 hours. (3-Aminopropyl)trimethoxysilane (320 L) was added to the mixture and held at 50 C. for 1 hour. To the hydrolyzed mixture was added 300 L of additional (3-Aminopropyl)trimethoxysilane. A transparent monolithic bed of a sol-gel C18 network was held at 50 C. for two days. The bed was crushed, ground and washed with methylene chloride. The ground particles were screened to isolate a narrow particle size distribution of C18 particles.

(56) Extraction Performance of Sol-Gel C18 Sorbents

(57) FIG. 1 shows a bar chart of the extraction efficiency of the various analytes in solution where the analytes display a wide range of polarity (partitioning between oil and water, log K.sub.ow). The structures and log K.sub.ow's of the analytes are shown in FIG. 2. As can be seen in the Figures, the sorbents, according to embodiments of the invention, are superior to commercially available C18 sorbents for compounds of log K.sub.ow less than 4 and equivalent for log K.sub.ow equal or greater than 4 that contain functional groups.

(58) All patents, patent applications, provisional applications, and publications referred to or cited herein are incorporated by reference in their entirety, including all figures and tables, to the extent they are not inconsistent with the explicit teachings of this specification.

(59) It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application.