FIELD OF THE INVENTION The present invention generally relates to the separation of analytes by gel electrophoresis, and more specifically relates to a novel method and apparatus for the separation of analytes using non-polymeric small molecule organogels and hydrogels, and to the identification and/or quantification of the separated analytes by various detection methods such as mass spectrometry.

BACKGROUND OF THE INVENTION For the last decade or so, a new class of gels formed from small molecular weight (typically less than 1000 AMU) organic molecules (called organic gelators or organogelling agents) has attracted considerable attention (Gronwald O. et al. Curr. Opin. Colloid In. 2002, 7, 148-156; Adballah, DJ. et al. Adv. Mater. 2000, 12, 1237-1247). Small molecule gels of organic gelators in aqueous solutions are often called hydrogels (or small molecule hydrogels), and small molecule gels of organic gelators in organic solvents are often called organogels (or small molecule organogels). Organogels and hydrogels are formed by self aggregation of small concentrations (typically <5%) of the gelator molecule in a solvent. The gels, which are formed in a variety of organic or aqueous solvents, are thermo reversible. Upon heating they form liquid solutions, and upon cooling the gels reform. They are also thixotropic, becoming liquefied upon mechanical agitation. Most of the known gelators contain one of a number of functional groups, the most common among them being sugars (Jung, J. H. el al. Chem. Eur. J. 2002, 8, 2684-2690; Kobayashi, H et al. J. Chem. Soc. Perkin Tram. 2 2002, 1930-1936), amino acids (Hanabusa, K. et al. Chem. Mater. 1999, 11, 649-655), short peptides (typically 1-1 1 amino acids) connected to an alkyl or aryl or another hydrophobic side chain (Aggeli, A. et al. J. Am. Chem. Soc, 2003, 125 (32): 9619-9628), amides (Bied, C. et al. J. Sol-Gel Sci. Techn. 2003, 26, 583-586; Yasuda, Y. et al. Chem. Lett. 1996, 575-576), ureas (Wang, G. et al. Chem. Comm. 2003, 310-311; van Esch, J. et al. Chem. Eur. J. 1999, 5, 937-950), and cholesterols (Jung, H.J. et al. J. Am. Chem. Soc. 2001, 123, 8785-8789). Alkanes can serve as gelators as well (Abdallah, DJ. et al. Chem. Mater. 1999, 11, 2907-2911). Despite the wide variety of gelators, they all have certain features in common. The aggregation occurs through non-covalent interactions, usually though not exclusively hydrogen bonding. Often one gelator combines several types of interactions such as π- stacking, van der Waals and hydrophobic interactions with hydrogen bonding. The resulting structures are twisted fibers which intertwine to trap solvent molecules, thus causing gelation. Bundles of fibers, rods and planar platelets or leaf-like supra-molecular structures are also encountered. While much of the focus has been on discovering new gelators and understanding the process of gelation, very little success has been recorded in finding applications for these materials. Several preliminary observations have been made regarding organogels. First, the ability to incorporate electrolytes into gels has been shown. Organogels have also been used as templates for inorganic, sol-gel derived chiral materials (Placin, F. et al. Chem. Mater. 2001, 13, 117-121). They have been found to gelate liquid crystals which may make them suitable for electrooptical displays (Mizoshita, N. et al. J. Mater. Chem. 2002, 12, 2197-2201). Gelators that can selectively gel one of a mixture of solvents have been found (Trivedi, D. R. et al. Chem. Mater. 2003, 75, 3971- 3973; Bhattacharya, S. et al. Chem. Commun. 2001, 185-186). This type of gelation may be used in handling oil spills. Also, electrolytic cells incorporating gelators have been fabricated (Kubo, W. et al. J. Phys. Chem. B 2001, 105, 12809-12815). PCT International Application WO 03/105788 describes the use of organogels for cosmetics. United States published patent application US 2003229029 describes therapeutic applications of organogels for treating muscle pain and spasm. The most widely used techniques for the separation and identification of biochemicals and other analytes involve gel electrophoresis (in both its planar and capillary forms) to separate the analytes, followed by detecting and quantifying the separated analytes using methods such as UV-VIS, diode array, electrochemical detection, radiolabel detection, calorimetry, fluorescence and mass spectrometry. Currently used matrices for gel electrophoresis include agarose, polyacrylamide, gelatin or another gel formed of cross linked polymers or long chain polymers. Various types of polyacrylamide gels exist, that vary in the degree of cross-linking and the nature of the surfactant included in the gel; the surfactant having the most widespread use is sodium dodecyl sulfate (SDS). Most often, the analytes are first separated on a gel plate (or in a capillary filled by a solid porous matrix). The gel is stained and/or fixated to view and quantify the resultant bands, using radioactive labels, fluorescent dyes or colorimetric reagents. Bands of interest can then be excised from the gel, and often must undergo de- staining of fluorescent or colored dyes, and removal of all traces of the gel, in order to proceed with analysis strategies. Conventional gels such as polyacrylamide gels have a number of drawbacks. For instance, they cannot be used to analyze hydrophobic compounds, because these compounds do not dissolve in aqueous gels. Furthermore, it can be a difficult and time- consuming process to insert the gels into a capillary tube. In addition, one of the major challenges in electrophoresis is identification of the separated compounds. The advent of capillary electrophoresis allowed for direct interface with electrospray mass spectrometry (abbreviated either as ESI-MS - for electrospray interfaced mass spectrometry, or ES-MS - for electrospray mass spectrometry). However, planar electrophoresis, which remains the heart of proteomics, is not suitable for direct MS detection. In conventional electrophoresis, the separated proteins and peptides must be located by staining, cut out of the slab, extracted from the matrix, cleaned of the stain, and only then injected into the MS for identification. The need to physically remove the proteins and peptides from the gels before MS is complicated, time-consuming and labor-intensive, and has prevented the development of a fully automated system for protein analysis. Moreover, these steps often necessitate the use of volatile solvents, which are potentially harmful to the researcher and to the environment. A different method for separation of the analytes from the gel involves application of electric force to drive the analytes off the gel. The gel can alternatively be blotted onto a membrane, and Edman degradation or Matrix-Assisted Laser Desorption-Ionization Mass Spectroscopy (MALDI-MS) can be performed directly on the membrane. In MALDI, a laser pulse is used to desorb and ionize the species of interest from a matrix in which it is embedded. The sequence or residues are read directly in the mass spectrometer. The ionization and desorption are often followed by Time of Flight (TOF) mass spectroscopy (Pacolsky & Winograd, 1999, Chem. Rev. 99(10), 2977-3005; Ekstrom et al., 2000, Anal. Chem. 72, 286). Although this technique eliminates the need for excision of bands, de-staining and purification from the gel, it is still labor-intensive. There is an unmet need in the art for an efficient electrophoretic method for the separation, identification and quantification of biochemicals, which does not require multiple steps of blotting, excision, de-staining and purification from gel remnants or aggressive laser desorption steps. SUMMARY OF THE INVENTION

The present invention relates to a method and apparatus for the separation of analytes by application of an electric field across a small molecule organogel or a small molecule hydrogel containing a mixture of the analytes. The separated analytes can subsequently be identified and/or quantified by directly transferring samples from the gel to a detector such as a mass spectrometer (MS). Organogels and hydrogels are made of small organic molecules (referred to herein as organic gelators or organogelling agents) and a solvent that form a porous gel structure held by non-covalent interactions between the small molecules. The molecules of the organogelling agent are capable of establishing, with each other, at least one physical non-covalent interaction (e.g., hydrogen bonding, π stacking, dipolar interactions and the like), leading to self-aggregation of these molecules so as to form a matrix which traps the solvent molecules, thereby forming the gel. Organogels are formed from small molecule organogelling agents in organic solvents, and hydrogels are formed from small molecule organogelling agents in aqueous solvents. The Applicants of the present invention have unexpectedly discovered that these organogels and hydrogels provide a new and versatile matrix for gel electrophoresis. Application of an electric field across the organogel or hydrogel permits separation of analytes based on their different mobilities in the solution within the gel and on their interaction with the compounds that form the organogel or hydrogel itself. The gels can be used for the separation of analytes such as amino acids, peptides, proteins, nucleic acids, oligonucleotides, porphyrins, polypyrrols, viruses, water pollutants, toxicants, pesticides, explosives, nitrocompounds, heavy metal ions, heavy metals complexes, pharmaceuticals and racemic mixtures of optically active compounds. The availability of many types of gelling which can gelate a large variety of organic and aqueous solvent systems of varying polarities allows for their extensive use in electrophoresis. Furthermore, the reversible nature of organogels and hydrogels (i.e., their thermo reversibility and thixotropic nature) makes them suitable for direct injection into a detector such as a mass spectrometer, for easy and facile determination and quantification of the separated analytes. As demonstrated herein, the Applicants have shown that separation of analytes such as amino acids, peptides and porphyrins can be achieved by capillary and planar electrophoresis using an organogel comprising the organic molecule trans-(lS,2S)-l,2- bis(dodecylamido)cyclohexane in an acetate buffer of the organic solvent acetonitrile and in mixtures of buffered acetonitrile and methanol. The applicants have also carried out electrophoresis of amino acids and proteins in hydrogels comprising the organic gelator N,N'-dibenzoyl-L-cystine-di(ethanolamide) in aqueous buffered solutions. The applicants have also carried out electrophoresis of proteins in a hydrogel comprising N,N'- dibenzoyl-L-cystine-di(ethanolamide) in the presence of up to 0.1% (w/w) sodium dodecyl sulfate, which is commonly used in polyacrylamide gels. It was further shown that the gels of the present invention can easily be inserted into a capillary tube by simply heating the gel up, injecting it into the capillary and cooling. Modifying compounds such as polyethylene glycol (PEG) can also be added in order to enhance the separation. Moreover, importantly, it was discovered that after separation the gel can be injected directly into a mass spectrometer for identification of the separated analytes. The gel was simply divided into small samples, which were liquefied by heating or by physically disturbing the gel with a syringe, and injected directly into a mass spectrometer. This type of direct transfer cannot be done with polymeric gels, because they cannot easily be liquefied and because the polymer matrix interferes with the MS analysis. With the organogel and hydrogel sections however, the Applicants were able to identify the separated analytes by mass spectrometry. These techniques can easily be automated, providing efficient and versatile methods for the separation of analytes in gel electrophoresis system. The ability to directly analyze (i.e., identify and/or quantify) the separated products by detection methods such as MS represents a major improvement over prior art separation methods. Thus, in one embodiment, the present invention relates to a method for the separation of analytes comprising the steps of contacting the analytes with a non- polymeric organogel or a non-polymeric hydrogel; and applying an electric field across the gel, thereby separating the analytes. The gels of the present invention can be in the form of a thin or thick planar film (planar gel) or they can be filled in a capillary (capillary gel) or tube (in-tube gel) or deposited in long cavities in a solid substrate (integrated microfluidic device). Any type of organic compound that is capable of gelation (i.e., formation of an organogel or a hydrogel upon contact with the appropriate solvent molecules), can be used for forming the gels of the present invention. Non-limiting examples of suitable organogelling agents include but are not limited to sugars, amino acids, cholesterols, short peptides (typically 1-11 amino acids) connected to an alkyl or aryl or another hydrophobic side chain, and compounds containing hydroxyl, carbonyl, amine, carboxylic acid, amide, benzyl, sulphonamide, carabmate, thiocarbamate, urea, thiourea, oxamido, guanidino and/or biguanidino functional groups. A currently preferred organogelling agent is a disubstituted cyclohexane such as 1,2- bis(dodecylamido)cyclohexane. Another currently preferred organogelling agent is a cystine-based compound such as N,N'-dibenzoyl-L-cystine di(ethanolamide). The organogelling agents can be mixed with any type of organic or aqueous solvent or solvent mixtures that will achieve adequate separation of the desired analytes. A buffer is typically added to the solvent or solvent mixture. Generally, any buffer system that is compatible with electrophoresis can be used. An organogel is formed upon cooling of a homogeneous mixture that is formed by mixing an organogelling agent with an organic solvent or solvent mixture. A currently preferred solvent for forming the organogels of the present invention is acetonitrile containing a buffer. Polar co-solvents such as alcohols (e.g., methanol) can be added in various concentrations in order to alter the polarity and enhance the resolution. A hydrogel is formed upon cooling of a homogeneous mixture that is formed by mixing an organogelling agent with an aqueous solvent or an organically-modified aqueous solvent (i.e., a mixture of a water-miscible organic solvent and water). A currently preferred solvent for forming the hydrogels of the present invention is water containing a buffer or a mixture of a water-miscible organic solvent in buffered water. According to a currently preferred embodiment, the solvent is a mixture of ethanol in water, for example 15% ethanol in water. It is also possible to introduce into the gels modifying molecules that are not covalently bonded to the gelator molecules which form the organogel or hydrogel network. These molecules can be used in order to enhance the separation of analytes by exploiting the different affinities between modifier and organogel. These molecules can also be used to alter the selectivity of the separation. Examples of such modifier compounds include but are not limited to oligomeric compounds; water soluble polymers; anionic, cationic or nonionic surface active agents (surfactants); polysaccharides and their esters; polyethylene oxide; polyimine and block polymers; and chiral selector molecules. A currently preferred such modifying compound is polyethylene glycol (PEG). The gel systems of the present invention can also be adapted to perform preparative gel electrophoresis and two-dimensional gel electrophoresis. Furthermore, the methods of the present invention can further include one or more additional separation steps after the organogel or hydrogel electrophoretic separation. These additional separation steps include, but not limited to chromatography (for example high performance liquid chromatography (HPLC), gas chromatograph (GC), or thin layer chromatograph (TLC)); distillation, electrophoresis in a second dimension in columns, capillaries, or on a planar plate; and/or membrane filtration. In all these techniques the separated analytes are removed from the gel via a syringe and injected into the inlet port of the separation device, or in the case of capillary organogel electrophoresis, the entire contents of the capillary are pumped into the inlet port of the second device. The present invention further relates to an apparatus which allows separation of analytes by electrophoresis in the small molecule organogels or hydrogels. The apparatus is comprised of a container comprising a non-polymeric organogel or hydrogel, which gel is connected at its two ends to a pair of electrodes that are connected to a power supply. Separation is achieved by application of an electric field between the two electrodes. The apparatus can be in the form of a box comprising a flat surface for holding a planar gel, or it can be in the form of a capillary or a tube for holding a capillary or an in-tube gel. The apparatus can also be in the form of long cavities in a solid substrate (integrated microfluidic device). The apparatus of the present invention can easily be incorporated into a system comprising means for detection of the separated analytes. Advantageously, the system of the invention can be automated, either fully or partially. One of the advantages of the organogels and hydrogels of the present invention, is the ability to couple gel electrophoresis and a detector such as a mass spectrometer, thereby allowing the direct identification and/or quantification of the separated analytes. The present invention thus provides a method for the identification and/or quantification of analytes, by contacting the analytes with a non-polymeric organogel or hydrogel; applying an electric field across the gel, thereby separating the analytes; and transferring a sample from the gel to a detector in order to identify and/or quantify the analytes. As mentioned above, prior art methods for the extraction of analytes from polyacrylamide and other planar electrophoretic gels prior to their analysis by mass spectrometry suffer from many disadvantages, including complicated and labor-intensive procedures in order to extract the separated analytes from the gels. The methods described herein enable easy, fast and non-labor intensive coupling of gel electrophoresis to a detector in order to identify and/or quantify the separated analytes. Using the small molecule organogels or hydrogels it is possible to introduce the gel and the analytes directly or indirectly into the detector without resorting to complex procedures for separation of the analytes from the gel. Examples of preferred MS detectors include but are not limited to an electrospray interfaced mass spectrometer (ESI-MS) and a matrix assisted laser desorption ionization mass spectrometer (MALDI-MS). The organogels and hydrogels of the present invention thus provide a new and versatile matrix for electrophoresis. They are suitable for planar, capillary and in-tube electrophoresis under widely different conditions. The availability of many types of organogelling agents which can gelate a large variety of organic and aqueous solvents of different polarities allows for the extensive use of organogels and hydrogels in electrophoresis. Most importantly, the reversibility of such gel systems allows their direct injection into a detector such as a MS for full recovery and identification of all separated analytes. In these ways and others, the gel systems of the present invention are superior to conventional polymeric gel systems currently in use. Further embodiments and the full scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1: Dependence of the mobilities of dansylated amino acids [serine (1), phenylalanine (2), tryptophan (3), proline (4) and histidine (5)] on solvent concentration. Dotted line and right axis represent the viscosity of acetonitrile- methanol mixtures.

FIGURE 2: Dependence of mobilities of dansylated amino acids [serine (1), phenylalanine (2), tryptophan (3), proline (4) and histidine (5)] on addition of PEG 200 to acetonitrile. FIGURE 3: Dependence of mobilities of dansylated amino acids [serine (1), phenylalanine (2), tryptophan (3), proline (4) and histidine (5)] on gelator concentration. Smoothed lines were added to guide the eye, with no theoretical basis.

FIGURE 4: Electropherograms at 20 kV of 14 amino acids in (A) buffer filled and (B) gel filled capillaries. Peak numbers are identified in Table 3.

FIGURE 5: Electropherograms at 1 IkV of five peptides in (a) buffer-filled and (b) gel-filled capillaries. Peak numbers are identified in Table 3.

FIGURE 6: (a) Time trace of m/z = 436 for consecutive injections of 0.3% organogel of 1 in acetonitrile acetate buffer containing tryptophan at different concentrations, (b) Typical mass spectrum of injections in (a) in negative mode, (c) Calibration curves for serine in solution (x) and gel (A) and tryptophan in solution (♦) and gel) (■).

FIGURE 7: Relative abundances of histidine (1, m/z 389), proline (2, m/z 347), tryptophan (3, m/z 436), phenylalanine (4, m/z 397) and serine (5, m/z 337) in each of the 13 compartments. Curves were added between points to guide the eye.

FIGURE 8: Electropherograms at 15 kV of five metal porphyrins in (A) buffer and (B) gel filled capillaries. Peak numbers are identified in Table 4.

FIGURE 9: Electropherograms based on MALDI analysis of planar gel separation of (A) 100 μM and (B) 200 μM porphyrins (numbers according to Table 4) with matrix α-cyano-hydroxycinnamic acid.

FIGURE 10: Electropherogram based on MALDI analysis of planar gel separation of 100 μM porphyrins (numbers according to Table 4) with no matrix. DETAILED DESCRIPTION OF THE PRESENT INVENTION The present invention relates to a method for the separation of analytes by contacting the analytes with a non-polymeric organogel or hydrogel; and applying an electric field across the gel, thereby separating the analytes. Oranogels and hydrogels do not suffer from most of the drawbacks of conventional gel systems such as polyacrylamide gels. One of the advantages of these gel systems is their reversible nature. While conventional polymeric gels require labor-intensive isolation procedures in order to identify and/or quantify the separated analytes, organogels and hydrogels can be liquefied locally by mechanical agitation with the needle of a syringe, by heating, or by introduction of a chemical that cleaves or disrupts the non-covalent bonds between the gelator molecules. The liquefied gel can then be injected directly into a detector system, for example a mass spectrometer. This simple technique allows the entire matrix or any part of the matrix to be analyzed. A particular advantage of organogels is that they can be made in organic solvents in addition to water. Conventional electrophoresis gels are aqueous polymeric gels. The ability to create gels in organic solvents enables the analysis of hydrophobic compounds which do not dissolve in aqueous gels, as well as the use of an entire group of new solvents which can be used as part of the separation matrix. In addition, organogels and hydrogels offer a much easier way to carry out capillary gel electrophoresis. Unlike polymer gel capillaries which require complicated polymerization procedures, these capillaries are made by a simple, one-step injection by filling the capillaries with a hot solution and then cooling to form the gel, and they are ready for use in only a few minutes. The evacuation of the capillaries is also veiy simple. The gel can be simply pumped out of the capillary with a syringe pump, with or without prior heat treatment, and after a short rinsing with a solvent, a new gel can be injected into the same capillary. Organogels and hydrogels are made of small organic molecules (organic gelators or organogelling agents) and a solvent that form a porous gel structure held by non- covalent interactions between the small molecules. Organogels are formed from small molecule organogelling agents in organic solvents, and hydrogels are formed from small molecule organogelling agents in aqueous solvents. The molecules of the organogelling agent are capable of establishing, with each other, at least one physical non-covalent interaction leading to self-aggregation of these molecules so as to form a matrix which traps the solvent molecules, thereby forming the gel. The physical interactions are diverse and include hydrogen bonding interactions, π interactions between unsaturated nuclei, van-der-Waals hydrophobic interactions, dipole — dipole interactions, and coordination bonds with organometallic derivatives. The establishment of these interactions can often be promoted by the architecture of the molecule, for example by the nature of the nuclei (e.g., aromatic nuclei), the presence of one or more unsaturated bonds, and the presence of asymmetric carbons. In general, each molecule of an organogelling agent can establish several types of physical interactions with a neighboring molecule. The term '"small molecule" as used herein refers to a low molecular weight molecule, typically having a molecular weight of less than 1,000, for example a molecular weight of 500-1000 which is characteristic of oligopeptides and oligosaccharides; a molecular weight of 400-600, which is characteristic of cholesterol based gelators; or a molecular weight of less than 400 which is characteristic of amino acid based gelators and mono and disaccharide based gelators. The term "gelling" means a thickening of the medium which can lead to a gelatinous consistency and even to a rigid, solid consistency which does not run under its own weight. The capacity to form this network of long range superamolecular structures and thus the gelling, depends on the nature (or the chemical category) of the organogelling agent, the nature of the substituents and the nature of the solvent and the external constraints (e.g., temperature, pressure etc.). This gelling is reversible under the action of an external stimulus such as heat or physical force or stress such as by mechanical agitation, or by addition of a chemical which breaks or disrupts the non- covalent bonds established between the organogelling agent molecules. The term "non polymeric organogel or hydrogel" as used herein refers to an organogel and hydrogel containing a non-polymeric organogelling agent. Any type of organic compound that is capable of gelation (i.e., formation of a gel upon contact with solvent molecules), can be used for forming the organogels and hydrogels of the present invention. Non-limiting examples of suitable organogelling agents include but are not limited to sugars such as monosaccharides and disaccharides, amino acids, short peptides (typically 1-11 amino acids) connected to an alkyl or aryl or another hydrophobic side chain), cholesterols, and compounds containing hydroxyl, carbonyl, amine (in the deprotonated form), carboxylic acid (in the protonated form), amide, benzyl, sulphonamide, carabmate, thiocarbamate, urea, thiourea, oxamido, guanidino and/or biguanidino functional groups. A currently preferred organogelling agent is a disubstituted cyclohexane such as l,2-bis(dodecylamido)cyclohexane. Another currently preferred organogelling agent is a cystine-based compound such as N5N'- dibenzoyl-L-cystine-di(ethanolamide). Examples of suitable gelling agents that can be used in the organogels and hydrogels of the present invention include but are not limited to: - amides of carboxylic acids such as tricarboxylic acids, for example cyclohexanetricarboxamides; - amides or esters of amino acids, for example esters of alanine and amides of valine; - amides of N-acylamino acids, for example the diamides resulting from the action of an N-acylamino acid with amines containing from 1 to 22 carbon atoms, such as those described in WO 93/23008, the contents of which are hereby incorporated by reference in their entirety, for example N-acylglutamides in which the acyl group is a Cg to C22 alkyl chain, and the dibutylamide of N-laurylglutamic; - diamides having hydrocarbon chains each containing from 1 to 22 carbon atoms, for example from 6 to 18 carbon atoms, these hydrocarbon chains being optionally substituted with ester, urea or fluoro groups, a such as those resulting from the reaction of diaminocyclohexane, for example trans-diaminocyclohexane, and of an acid chloride; - amides or amines of steroids, such as those of deoxycholic, cholic, apocholic or lithocholic acids, and salts thereof; - compounds containing several aromatic nuclei (e.g., 3), such as anthrylic derivatives comprising at least two alkyl chains containing from 8 to 30 carbon atoms, for example 2,3 -bis (n-decyloxy) anthracene or 2,3 -bis (n-decyloxy) anthra- quinone, or comprising a steroid group, for example cholesteryl 4- (2-anthryloxy) butanoate or cholesterylanthraquinone-2-carboxylate and derivatives thereof; - azobenzene steroids; - benzylidene sorbitols or alditols and derivatives thereof, for example 1, 3: 2,4- di-o- benzylidene-D-sorbitol; - cyclodipeptides which are cyclic condensates of two amino acids; - cyclic compounds or alkylene compounds comprising two urea or urethane groups such as dialkylurea cyclohexane; - alkylaryl derivatives of cyclohexanol in which the alkyl chain is linear or branched and comprises froml to 22 carbon atoms, and the aryl part is for example a phenyl group, these derivatives being for example 4-tert-butyl-l-phenylcyclohexanol; - calixarenes; - combinations of 2,4, 6-triaminopyrimidines which are substituted with an alkyl chain and of dialkylbarbituric acid, the alkyl chains thereof being linear or branched and comprising from 1 to 22 carbon atoms; - the organogelling agents described in WO 01/07007, the contents of which are hereby incorporated by reference in their entirety; - gluconamide derivatives such as those described in the article R. J. H. Hafkamp, Chem. Commun., (1997), pages 545-46, and in the article J. Org. Chem., vol. 64, No. 2; 412-26 (1999), the contents of which are hereby incorporated by reference in their entirety; - cyclic ether derivatives; - diamide, diurea or urethane derivatives of amino acids such as: a) the bisoxalylamides of amino acids cited in the article by M. Jokic, J. Chem, Soc. , Chem. Commun. , pages 1723-24 (1995), the contents of which are hereby incoiporated by reference in their entirety; b) the amide and urea derivatives of a lysine ester such as those mentioned in the article by K. Hanabusa, Chemistry Letters, pp. 1070-71,2000, the contents of which are hereby incorporated by reference in their entirety, c) diamide derivatives of benzenedicarboxylic acids and of valine such as those mentioned in the article by K. Hanabusa, Chemistry Letters, pp. 767-8, 1999, the contents of which are hereby incorporated by reference in their entirety; - monoalkyloxamides such as those described by X. Luo, Chem. Commun., pp.2091-92, 2000, the contents of which are hereby incoiporated by reference in their entirety; - bolaamphiphiles with al-glucosamide head such as N,N'-bis(ss-D- glucopyranosyl)-n-alkane-l- dicarboxamide, such as the compounds mentioned in the article by T. Shimizu, J. Am. Chem. Soc. , 119, pp. 2812-18,1997, the contents of which are hereby incoiporated by reference in their entirety; - bolaamphiphilic amides derived from amido acids described in K. Hanabusa, Adv. Mater., 9, No. 14, 1997, pp. 1095-1097, the contents of which are hereby incoiporated by reference in their entirety; - 2-alkyl-2-ammoniumisobutyl acetate p-toluenesulphonate salts such as those described by K. Hanabusa, Colloid Polym. ScL, 276, pp. 252-59,1998, the contents of which are hereby incoiporated by reference in their entirety; - fatty esters of cellobiose such as those mentioned in WO 00/61080 and WO 00/61081, the contents of which are hereby incoiporated by reference in their entirety; -the organogelling agents having two urea groups and two carbamate groups mentioned in U.S. 6,156,325. the contents of which are hereby incorporated by reference in their entirety; and - the organogelling agents described in WO 03/105788, the contents of which are hereby incorporated by reference in their entirety. It is also possible to use mixtures of the various organogelling agents described above. Among the compounds which can be used as organogelling agents in the methods of the present invention, the following non-limiting examples are mentioned: - N, N'-bis (dodecanoyl)- 1 , 2-diaminocyclohexane, in particular in the trans form, also known as (2-dodecanoylamino- cyclohexyl) dodecanamide). This compound is described in particular by Hanabusa K.; Angew. Chem., 108, 1997, 17, pages 2086-2088, the contents of which are hereby incorporated by reference in their entirety; - N, N'-bis (dodecanoyl)- 1, 3-diaminocyclohexane, in particular in the trans form, also known as(3-dodecanoylamino- cyclohexyl) dodecanamide), - N, N'-bis (dodecanoyl)- 1 , 4-diaminocyclohexane, in particular in the trans form, also known as(4-dodecanoylamino- cyclohexyl) dodecanamide), N,N'-bis(dodecanoyl)-l, 2-ethylenediamine, also known as (2- dodecanoylaminoethyl) dodecanamide), -N, N'-bis (dodecanoyl)-l-methyl-l, 2- ethylenediamine, also known as (2- dodecanoylaminopropyl) dodecanamide), - N, N'-bis (dodecanoyl)- 1, 12-diaminododecane, also known as (2- dodecanoylaminododecyl) dodecanamide), - N, N'-bis (dodecanoyl) -3, 4-diaminotoluene, also known as (2- dodecanoylamino-4-methylphenyl) dodecanamide), - 20-cis-l,3, 5-tris (dodecylaminocarbonyl) cyclohexane, - cis-1, 3, 5-tris (octadecylaminocarbonyl) cyclo- hexane, - cis-1, 3,5-tris [N- (3, 7-dimethyloctyl) aminocarbonyl]- cyclohexane, -trans- 1, 3,5-trimethyl-l, 3,5-tris (dodecylaminocarb- onyl) cyclohexane, and -trans- 1, 3, 5-trimethyl-l, 3,5- tris (octadecylaminocarbonyl) cyclohexane. Examples of gelators that are especially suitable for forming hydrogels in aqueous solutions include but are not limited to compounds containing one or more of mono, di, and oligosaccharide moieties; compounds containing amino acids, di, tri and oligopeptides; fatty acids and amides; pyridinyl containing compounds; organic ammonium or phosphate salts; and gemini surfactants. Hydrogels are formed by the same method as organogels. Any type of solvent system that will achieve adequate separation of the particular analytes can be used in the organogels and hydrogels of the present invention. The polarity of the solvent can range from nonpolar solvents such as alkanes and toluene to polar solvents such as water and water/ethanol solutions. Solvent mixtures are also possible. The polarity of the solvent/solvent mixture can be adjusted to achieve optimal separation of the desired analytes. A buffer is typically added to the solvent or solvent mixture, in order to ensure compatibility with electrophoretic systems. Suitable buffers include but are not limited to acetic acid/acetate or other carboxylic acid/carboxylate buffers, tris, phosphate, ortho- phosphate, borate and carbonate based buffers. Any other organic or inorganic weak acid - base pairs can also be used. An organogel is formed upon cooling of a homogeneous mixture that is formed by mixing an organogelling agent with an organic solvent or solvent mixture. Suitable organic solvents include, but are not limited to, acetonitrile; halogenated solvents such as chloroform and methylene chloride; ketones such as methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone and acetone; alcohols such as methanol, ethanol, isopropanol and cyclohexanol; glycols such as ethylene glycol, propylene glycol and pentylene glycol; short-chain esters such as ethyl acetate, methyl acetate, propyl acetate, n-butyl acetate and isopentyl acetate; ethers such as diethyl ether, dimethyl ether and dichlorodiethyl ether; alkanes such as decane, heptane, dodecane, hexane and cyclohexane; cyclic aromatic compounds such as benzene, toluene and xylene; and aldehydes such as benzaldehyde and acetaldehyde. Polar co-solvents such as alcohols (e.g., methanol, ethanol and the like) can be added in various concentrations in order to alter the polarity and enhance the resolution. A currently preferred solvent system is a mixture of acetonitrile and buffer, with or without methanol. A hydrogel is formed upon cooling of a homogeneous mixture that is formed by mixing an organogelling agent with an aqueous solvent or an organically-modified aqueous solvent (i.e., a mixture of a water-miscible organic solvent and water). A preferred solvent for forming the hydrogels of the present invention is buffered water. An organically-modified aqueous solvent, i.e., a mixture of a water-miscible organic solvent and water, can also be used to form the hydrogels of the present invention. A small amount of an organic solvent such as methanol, ethanol, DMSO etc. is added to help the gelator dissolve. The concentration of the water-miscible organic solvent in water can vary depending on the electrophoresis system being used, and the analytes being separated. Suitable concentrations include 0-50% water-miscible organic solvent in water. According to a currently preferred embodiment, the solvent is a mixture of water and an alcohol, for example ethanol. A currently preferred aqueous system is 15% ethanol in water. The gels of the present invention can be in the form of a thin or thick planar film, typically having a thickness ranging from 0.5 mm to 3 mm, and a length ranging between 3 and 30 cm for example 1 mm x 10 cm; 2 mm x 20 cm, or they can be filled in a capillary or tubes typically having a thickness of about 50-500 μm, for example 100 μm, 75μm and 50 μm or deposited in long cavities in a solid substrate (integrated microfluidic device). The cavity can be suitable for lab on a chip- separation as described for example in the article Integrated microfluidic devices Erickson D5 Li DQ Analytica Chimica Acta 2004, 507 (1): 1 1-26. The concentration of the gelator in the gel can vary. Typical concentration ranges are 0.1-10% by weight-gelator based on the weight of gelator plus solvent molecule, for example 0.3?/o, 1%, 3%, 5% and 10% by weight of the gelator molecule. It is also possible to introduce into the gels modifying molecules that are not covalently bonded to the gelator molecules which form the organogel or hydrogel network. These molecules can be used in order to enhance the separation of analytes by exploiting the different affinities between modifier and organogel. These molecules can also be used to alter the selectivity of the separation. Examples of such modifier compounds include but are not limited to oligomeric compounds (e.g., glycol ethers such as polyetheyle glycol and polypropylene glycol); water soluble polymers (e.g., polyvinyl alcohol (PVA), chitosan, polysaccharide and polyethyleneimine); anionic surface active agents or surfactants (e.g., sodium dodecyl sulfate), cationic surface active agents (e.g., cetylpyridinium bromide (CPB), and cetyltrimethylammonium bromide (CTAB)), nonionic surface active agents (e.g., poly(oxyethylene)ethers;) polysaccharides and their esters; polyethylene oxide; polyimine and block polymers such as PEO-PPO-PEO; and chiral selector molecules (e.g., cyclodextrins, crown ethers, amino acid containing compounds and polypeptides). A currently preferred such modifying compound is polyethylene glycol (PEG). Furthermore, it is possible to introduce into the gels dispersion of nanoparticles (nanoparticulate dispersions) that are not attached to the gels by covalent bonding and which alter the selectivity of the separation compared to the separation in a matrix containing only the gel or only the solid particles. The nanoparticulate dispersions preferably have a particle size of less than 2000 urn, more preferably less than 1000 nm, and even more preferably less than 500 nm. The nanoparticulate dispersions can be made of, e.g., metals such as gold, silica gels, organically modified silica gels (e.g. octyl, cyanoalkyl, aryl, amine or amide-modified silica gels), metal oxides, organically modified metal oxides (e.g., octyl, cyanoalkyl, aryl, amine or amide-modified metal oxides), polystyrene, latex and the like. For example, stationary gold nanoparticles interact with the analyte and alter their electrophoretic mobilities. The difference in the electrochromtographic mobilities results in improved separation (see for example Separation of long double-stranded DNA by nanoparticle-filled capillary electrophoresis Huang MF, et al. Analytical Chemistry, 2004, 76 (1): 192-196 2004). Assymetric (chiral) organogels based on small assymetric molecules in solvents have already been reported, for example cholesterol based gelators such as 3-b- cholesteryl-4-(2-anthryloxy)butanoate (Y.-C. Lin, R. G. Weiss, Macromolecules 1987, 20, 414), or amino acid based gelators such as L-cystine derivatives (Menger FM, Caran KL5 JACS 2000, 122, 11679). It is therefore also possible to carry out chiral separations of enantiomers by exploiting different non-covalent interactions between the gel forming molecules and the different enantiomers that are introduced in the sample. Suitable chiral organogels include, but are not limited to, gelators containing cholesterol, amino acids, sugars, and disubstituted cyclohexanes. The gels of the present invention can be used for the separation of analytes such as amino acids, peptides, proteins, nucleic acids, oligonucleotides, porphyrins, polypyrrols, viruses, water pollutants, toxicants, pesticides, explosives, nitrocompounds, heavy metal ions, heavy metals complexes, pharmaceuticals and racemic mixtures of optically active compounds. According to certain embodiments, the analytes can be derivatized in order to allow for easier detection. For example, amino acids are commonly used model compounds which are derivatized to allow for easier detection by UV, calorimetry, fluorescence microscopy, radiolabel detection, etc. One such derivatizing agent is Sanger's reagent (l-fluoro-2,4-dinitrobenzene (FDNB), which reacts with the N-terminal residue under alkaline conditions. The derivatized amino acid can be hydrolyzed and will be labeled with a dinitrobenzene group that imparts a yellow color to the amino acid. Separation of the modified amino acids (DNP-derivative) by electrophoresis and comparison with the migration of DNP-derivative standards allows for the identification of the N-terminal amino acid. Another example is dansyl chloride, which reacts with the N-terminal residue under alkaline conditions. Analysis of the modified amino acids is carried out similarly to the Sanger method except that the dansylated amino acids are detected by fluorescence. This imparts a higher sensitivity into this technique over that of the Sanger method. Another example is the use of the reagent ninhydrin, which provides an intense blue color, except for proline, where a yellow color is obtained due to the presence of the secondary imino group. Furthermore, Edman degradation enables the identification of an entire peptide sequence, since it allows for additional amino acid sequence to be obtained from the N-terminus inward. This method utilizes phenylisothiocyanate to react with the N-terminal residue under alkaline conditions. The resultant phenylthiocarbamyl derivatized amino acid is hydrolyzed in anhydrous acid. The hydrolysis reaction results in a rearrangement of the released N-teraiinal residue to a phenylthiohydantoin derivative. As in the Sanger and Dansyl chloride methods, the N-terminal residue is tagged with an identifiable marker, however, the added advantage of the Edman process is that the remainder of the peptide is intact. The entire sequence of reactions can be repeated over and over to obtain the sequences of the peptide. This process has subsequently been automated to allow rapid and efficient sequencing of even extremely small quantities of peptide. Another preferred derivatization involves the derivatization of proteins with 5-carboxyfluorescein, succinimidyl ester to form fluorescent spots in gel electrophoresis. Another preferred derivatization involves the derivatization of oligonucleotides with the cyanine dyes such as YO, YO-YO and YO-PRO to form fluorescent spots in gel electrophoresis. The organogels and hydrogels of the present invention separate the analytes based on a particular characteristic of the analytes, for example electronic charge. If there are multiple analytes with the same charge, they will not separate. Therefore, the present invention also contemplates perfonning one or more additional separation step(s) after the organogel or hydrogel separation has taken place. The additional separation is based on a different characteristic of the analytes, for example size. Examples of such additional separation steps include, but not limited to chromatography (for example high performance liquid chromatography (HPLC), gas chromatograph (GC), or thin layer chroniatograph (TLC)); distillation, electrophoresis in a second dimension in columns, capillaries, or on a planar plate; and/or membrane filtration. In all these techniques the separated analytes are removed from the gel via a syringe and injected into the inlet port of one or more separation device(s), for example HPLC, GC or TLC, or a gel electrophoresis apparatus. In the case of capillary organogel or hydrogel electrophoresis, the entire content of the capillary is pumped stepwise into the inlet port of the second device(s), thus achieving resolution of analytes that did not separate well in the capillary gel. The additional separation step can also include one or more of the conventional unit operations described in the book (M. McCabe, JC Smith and P. Harriott, Unit operations in chemical engineering, 5th ed. McGraw hill, Inc. NY, 1993), the contents of which are hereby incorporated by reference herein, such as distillation, extraction, adsorption, absorption, stripping, drying, membrane separation processes, and crystallization. The present invention further relates to an apparatus for use according to the methods of the present invention and which allows separation of analytes by electrophoresis in the small molecule organogels or hydrogels. When the gel is a planar gel, the apparatus is typically comprised of a container such as a mould box to cast the organogel film on a flat surface. The flat surface is connected at its two ends to two electrodes (usually via a buffer solution) that are connected to a power supply. Separation is made by application of electric field between the two electrodes. The choice of the appropriate electric field is known to a person skilled in the art. The present invention further relates to an apparatus for use according to the methods of the present invention and which allows separation of analytes by electrophoresis in organogels or hydrogels that are filled in a capillary or a multiplicity of capillaries. The apparatus is comprised of a capillary tubing filled with the gel (preferably the gel is introduced in a heated form above the gel formation temperature). The capillary is connected at its two ends to two beakers in which are immersed two electrodes that are connected to a power supply. The apparatus can further comprise one or more additional separation device(s) for further separating the analytes after the organogel or hydrogel electrophoretic separation. The additional separation(s) can be conducted by methods such as chromatography (for example high performance liquid chromatography (HPLC), gas chromatograph (GC), or thin layer chromatograph (TLC)); distillation, electrophoresis in a second dimension in columns, capillaries, or on a planar plate; and/or membrane filtration. Thus, the apparatus of the present invention can contain one or more devices suited to carry out any of these separation step(s). The additional separation device(s) can further include one or more devices for carrying out the conventional unit operations describe above. One of the objectives of the present invention is to provide a method that allows simple coupling of planar and capillary gel electrophoresis and a detector such as a mass spectrometer, thereby allowing the direct identification and/or quantification of the separated analytes. According to this method, after separating the analytes using the organogels or hydro gels of the present invention, a sample from the gel is liquefied, for example by heating, by mechanical agitation, or by introduction of a chemical that cleaves the non-covalent bonds between the gelator molecules, and the liquefied sample is simply transferred to a detector in order to identify and/or quantify the analytes. In contrast to prior art electrophoretic methods, the methods described herein enable easy, fast and non-labor intensive coupling of gel electrophoresis to a detector in order to identify and/or quantify the separated analytes. Using the small molecule organogels or hydrogels it is possible to introduce the gel and the analytes directly or indirectly into the detector without resorting to complex procedures for separation of the analytes from the gel. Any detector commonly known in the art can be used in the methods of the present invention. Suitable detectors include but are not limited to a mass spectrometer (MS), ultraviolet (UV) detector, ultraviolet-visible (UV-VIS) detector, calorimeter, diodearray, electrochemical detector, fluorescence detector and radiolabel detector. A particularly preferred detector for use in the methods of the present invention is a mass spectrometer. Examples of preferred MS detectors include but are not limited to an electrospray interfaced mass spectrometer (ESI-MS) and a matrix assisted laser desorption ionization mass spectrometer (MALDI-MS). According to one embodiment of the present invention, it is possible to separate the analytes using an organogel or hydrogel comprised of organic molecules and then after separation and evacuation of most of the solvent to perform matrix assisted laser desorption ionization - MS (MALDI-MS). The organic compound that forms the organogel can enhance the ionization and transport of the analytes to the MS analyzer. Commonly used MALDI desorption-enhancing reagents include for example-2,4,6 - trihydroxy acetophenone; sinapinic acid; α-cyano-4-hydroxy cinnamic acid (CHCA); dihydroxybenzoic acid; hydroxy picolinic acid; anthranilic acid; nicotinic acid; salicylamide; succinic acid; ferulic acid; caffeic acid; poiphyrins; metal porphyrins; and 4-nitroaniline In another embodiment, the present invention further provides a method and apparatus for the coupling of planar organogel or hydrogel electrophoresis and mass spectrometry by introduction of the separated analytes from the electrophoresis apparatus into a mass spectrometer such as MALDI - MS or ESI - MS. The electrophoresis apparatus is comprised of a flat plate equipped at its two ends with electrodes that can be connected to a DC power supply, which can be transferred easily to a detector such as a mass spectrometer, e.g. a MALDI-MS or ESI-MS apparatus. In another embodiment, the present invention further provides a method and apparatus for the coupling of capillary organogel or hydrogel electrophoresis and mass spectrometry by introduction of the separated analytes from the electrophoresis apparatus into a mass spectrometer such as MALDI - MS or ESI - MS. This is earned out by pumping a fluid that forces the gel and the analyte out of the capillary and into the mass spectrometry through an interconnected capillary. Detection of the analytes by mass spectrometry according to the methods of the present invention can be conducted in accordance with the literature procedure described in Michalski WP, et al. Analytica Chimica Acta, 1999, 383 (1-2): 27-46, the contents of which are hereby incorporated by reference in their entirety. One of the advantages of the gels of the present invention is their thermo- reversibility and thixotropy, which enables their simple and direct transfer to a detector for the identification and/or quantification. The gel is normally solid, but it can easily be disturbed and liquefied by a number of methods such as by physically disturbing the gel, by heating, or by introduction of a chemical that cleaves the non-covalent bonds between the gelator molecules. Physical disturbance can be achieved by mechanical agitation, such as by applying shear force or shear stress (e.g., by repeatedly moving the syringe). Local heating of the gel can be achieved by using a heated needle of a syringe, a heating element, or an external infra red emitter. Chemicals which can disrupt the non-covalent bonds of the organogels and hydrogels include but are not limited to urea, guanidine hydrochloride, dimethylamino benzaldehyde, sodium fluoride and salts of other small ions. The liquefied gel can then be directly transferred to the detector with a syringe, with a pump, by applying a pressure gradient, by applying electrophoretic force, or by any other method known in the art. The transfer can be manual or it can be automated (e.g., by using a robot arm). In one embodiment, the gel is first divided into several samples, and each sample is separately disturbed and transferred into the detector for identification/ quantification. In one embodiment, after separation, the gel is dried and laser irradiation in the UV or visible or IR region is applied in order to desorb the analytes and transfer them to a mass spectrometer. In order to facilitate the transfer of analytes to the mass spectrometer it is customary to add to the matrix compounds that assist the transfer. Commonly used matrix compounds include but are not limited to2,4,6 -trihydroxy acetophenone; sinapinic acid; α-cyano-4-hydroxy cinnamic acid (CHCA); dihydroxybenzoic acid; hydroxy picolinic acid; anthranilic acid; nicotinic acid; salicylamide; succinic acid; ferulic acid; caffeic acid; porphyrins; metal porphyrins; and 4-nitroaniline. In a further embodiment, the methods of the invention further include the addition of small molecules to the gel in-order to enhance matrix assisted laser desorption and thus allow matrix assisted laser desorption mass spectrometry. Examples of such small molecules include but are not limited to any of the matrix compounds listed above. In yet another embodiment, the small gelator molecules also enhance matrix assisted laser desorption and thus allow matrix assisted laser desorption mass spectrometry. The following examples are presented in order to more fully illustrate certain embodiments of the invention. They should in no way, however, be construed as limiting the broad scope of the invention. One skilled in the art can readily devise many variations and modifications of the principles disclosed herein without departing from the scope of the invention.

EXPERIMENTAL DETAILS SECTION

Example 1 - Planar Electrophoresis Oganogels were formed by adding 6 mg of tvcms-( \ S, 2S)- 1,2- Bis(dodecylamido)cyclohexane (1) to 2 ml of buffer, heating until dissolution and casting into the electrophoresis cell. The buffer used consisted of IM acetic acid and 25 mM ammonium acetate in acetonitrile or mixtures of acetonitrile with methanol. The gel was deposited in a planar shallow box. Gel dimensions after deposition were 2 mm thick x 2.5 cm wide x 6 cm long. Separation was conducted by application of 300 V between two electrodes located at two cavities at the two ends of the organogel. Visualization was carried out by illumination of the gel with UV light. Figure 1 shows the mobilities of five dansylated amino acids in planar gels of different acetonitrile-methanol mixtures. The following dansylated amino acids were used for separation: serine (1), phenylalanine (2), tryptophan (3), proline (4) and histidine (5). The compounds all moved in the direction of the anode, indicating their negative charge in the buffers. In all cases the five compounds were resolved by visual inspection of the UV-illuminated spots. The vertical uncertainty bars were calculated from the radius of the fluorescent spots. The dotted line and right axis represent the viscosities of the different acetonitrile-methanol mixtures, which are assumed to be the local viscosities encountered by the analytes. The minimum in the viscosity corresponds to the maximum in the mobility. The selectivity between consecutive amino acid pairs in the different solvents is given in Table 1. These results show the versatility and adaptability of organogel systems to electrophoresis. Different solvents can be used in order to control the separation of a group of analytes or a specific analyte pair. Proline and tryptophan have the best resolution in pure acetonitrile, -while phenylalanine and serine separate better in the 50% mixture. Analytes that are difficult to resolve can potentially be resolved with a change in the solvent.

Table 1. Selectivity in acetonitrile-methanol mixtures

DNS-amino acid Selectivity between amino acid pairs MeCN 10% MeOH 25% MeOH 50% MeOH Histidine 2.23 2.02 1.92 2.39 Proline 2.30 1.97 1.74 1.51 Tryptophan 1.35 1.31 1.36 1.42 Phenylalanine 1.15 1.24 1.23 1.28 Serine The results presented in Figure 1 and Table 1 demonstrate the ability to separate analytes by planar electrophoresis. The results also demonstrate that the choice of appropriate solvents can specifically control the separation of a group of analytes or a specific analyte pair.

Example 2 - Effect of Additives Polyethylene glycol (PEG) has been shown to improve the strength of oganogels, without interfering with their conductivity (Hanabusa et al. Chem. Mater. 1999, 11, 649- 655). Since by addition of PEG it is possible to tune the viscosity over a much larger range (as compared with a mixture of solvents), the Applicants tested whether it is possible to alter the selectivity of the organogels by adding different amounts of PEG. The mobilities of the dansylated amino acids [serine (1), phenylalanine (2), tryptophan (3), proline (4) and histidine (5)] were measured with differing concentrations of PEG 200 in 0.3% gelator (1) acetonitrile organogel. The gelator concentration was kept constant in all of these tests. Separation was carried out according to the protocol of Example 1. The observed mobilities in the planar electrophoresis configuration are shown in Figure 2, and the selectivities between adjacent amino acid pairs listed in Table 2. Indeed, increasing the level of the modifier decreased the observed mobilities by up to 70%, probably due to the increased viscosity. The selectivities here too show a different dependence on the modifier for each pair of analytes. The histidine-proline separation improves with added PEG while the proline-tryptophan selectivity is reduced.

Table 2. Selectivity in acetonitrile-PEG mixtures DNS-amino Selectivity between amino acid pairs acid MeCN 10% PEG 20% PEG 30% PEG 40%PEG Histidine 2.23 2.58 2.39 2.76 3.00 Proline 2.30 2.12 1.78 1.57 1.52 Tryptophan 1.35 1.31 1.34 1.38 1.47 Phenylalanine 1.15 1.13 1.13 1.11 1.13 Serine The results presented in Figure 2 and Table 2 demonstrate that the separation resolution can be altered and optimized by the introduction of the appropriate type and amount of oligomeric modifier.

Example 3 - Effect of the Concentration of the Gelator Figure 3 shows the dependence of mobilities of dansylated amino acids [serine (1), phenylalanine (2), tryptophan (3), proline (4) and histidine (5)] on gelator (1) concentration. Smoothed lines were added to guide the eye, with no theoretical basis. The figure illustrates that the separation resolution can be altered by changes of the concentration of the gelator trans-(lS, 2S)-1,2-Bis(dodecylamido)cyclohexane.

Example 4 - Capillary Electrophoresis The separation of a mixture of 14 dansylated amino acids was carried out in both gel-filled and buffer-filled capillaries. As stated above, the dansylated acids are all negatively charged in this system. Since in the gel there is no electroosmosis, and electrophoretic mobility is the only force acting on the analytes, separations were performed in negative polarity mode (i.e., with the detector located near the anode). In the buffer-filled capillaries, electroosmotic flow marker mesityl oxide was found to have a mobility of 3.4 x 10"4 cm V"1 S"1 toward the cathode, which is greater than the electrophoretic mobilities of all the amino acids toward the anode, with the exception of aspartic acid. Therefore, positive polarity was used, and the compounds were detected in the reverse order of that in the gel-filled capillaries. Figure 4 shows electropherograms of 14 amino acids in (A) buffer filled and (B) gel filled capillaries of different dansylated amino acids. The peaks were identified by individual injection of each acid. The retention times, mobilities, and plate counts for the gel separation are given in Table 3.

Table 3. Separation Data for Gel-Filled Capillaries3

compound /γ (min) // (10"4 Cm2 V1 S"1) N

1. dansyl chloride 4.3 3.02 16000 2. aspartic acid 5.0 2.60 14000 3. cysteine 5.2 2.47 16000 4. threonine 9.4 1.38 16000 5. serine 9.6 1.35 13000 6. glycine 12.1 1.07 20000 7. phenylalanine 12.7 1.02 22000 8. alanine 13.2 0.980 24000 9. tyrosine 14.3 0.905 28000 10. glutamine 15.0 0.866 14000 11. asparagine 17.1 0.759 24000 12. valine 17.7 0.734 19000 13. tryptophan 18.2 0.712 7000 14. leucine 19.2 0.676 8000 15. histidine 23.5 0.551 12000 16. dansyl chloride 9.3 3.10 12000 17. glutathion (glu- 13.0 2.22 94000 cys-gly) 18. gly-ser 37.1 0.777 85000 19. glu-glu 47.9 0.602 35000 20. ala-gln 60.6 0.475 41000 21. phe-ala 67.5 0.427 39000 α N values were calculated by the formula N = 5.54(^/W)" where W is the half-height peak width

The results clearly show the advantages of the organogel. Baseline resolution was achieved for 10 of the 14 compounds, whereas in the buffer several peaks fell on top of one another. This illustrates the resolving power of the new matrix and the ability to separate analytes within this gel by capillary electrophoresis. Example 5 - Separation Of Peptides In order to demonstrate the adaptability of the system to larger compounds, a series of di- and tripeptides was separated. The buffer solvent was changed from pure acetonitrile to acetonitrile-methanol (3:2) to ensure proper solubility of the analytes. The resulting electropherogram is shown in Figure 5, and the corresponding separation characteristics are delineated in Table 3 above. Electroosmosis in the acetonitrile- methanol gel-filled capillaries was negligible as in the acetonitrile-based gels, but the change of solvent rendered the electroosmosis in the conventional CE test (upper curve of Figure 5) negligible, and therefore the test was done in negative mode. Here too, full baseline separation was achieved in the gel, which was not possible in the buffer-filled capillaries. These results show that it is possible to modify the system to be used for larger molecules and highlight the versatility of organogels in that they permit adaptation of the solvent in order to accommodate different analytes.

Example 6 - Direct MS Interfacing One of the important advantages of the organogels and hydrogels is the ability to inject the gel directly into the mass spectrometer, thus attaining by definition 100% recovery of the analytes. Full recovery is indeed common practice for capillary electrophoresis but not for planar gels. Theoretically, full recovery is possible also for other polymer-based gels, but in practice the polymeric matrix or its degradation products interfere with the mass spectrometric analysis. As a first step toward establishing the feasibility of direct injection of the gel, the Applicants have compared trie calibration curves of the different dansylated analytes in acetonitrile acetate buffer solution and organogels of 1. The sensitivities obtained for the different analytes that Λvere injected from the gels ranged between 73% and 85% of the respective calibration curves of the same analytes from the solution phase. Two typical examples for dansyl tryptophan and dansyl serine are shown in Figure 6. The figure also shows the mass spectrum of one of the calibration injections for tryptophan. The mlz 436 peak is the molecular ion. The mlz 223 and 250 peaks appeal4 in all the injections and are fragments of the dansyl group, oxidized demethylized dansyl and dansylamine, respectively. In order to illustrate the ability to inject the gel and analytes directly into a mass spectrometer, the Applicants performed the separation of 5 dansylated amino acids as described above. After the separation was completed, the gel was divided into 13 compartments by placing a plastic grating on the gel. The 4-mm size of the grating provided a sample of about 10 mL which was necessary for injection into the MS. Samples from each of the 13 compartments were mixed with the needle of the syringe for Is, and the slurry was injected into a sample loop of the MS. Figure 7 depicts the relative abundances of histidine (1, m/z 389), proline (2, m/z 347), tryptophan (3, m/z 436), phenylalanine (4, m/z 397) and serine (5, m/z 337) in each of 13 different injections. The different levels in each of the compartments are connected by a line to guide the eye, forming a chromatogram presentation. This mode of planar electrophoresis offers full recovery of the analytes. Similar procedure was carried out with local liquefaction by local heating and gave similar results. The reversible nature of organogels thus allows them to be injected directly into the MS for identification of the compounds separated on. them and obviates the need for complicated and time-consuming extraction procedures.

Example 7 - Porphyrin separation in capillaries A further example of the use of trcms-{\S, 2S)-1, 2- Bis(dodecylamido)cyclohexane is the separation metal porphyrins. Five porphyrins were separated in gel-filled and buffer-filled capillaries at 15 kV and detected by absorbance at 465 nm. The buffer was IM acetic acid-25 mM ammonium acetate in acetonitrile. The electropherograms are shown in Figure 8 with the data listed in Table 4.

Table 4. Separation Data for Gel-Filled Capillaries"

Compound tt(min) //(10-4Cm2V"11 S"1) N

1. Manganese (III) porphyrin 17.7 1.22 12000

2. Manganese (III) diphenyl porphyrin 18.2 0.982 15000

3. Manganese (III) tetraphenylporphyrin 19.2 0.885 17000

4. OEP-I 23.5 0.782 13000

5. Zinc (∏) tetra(methylpyridinyl) 17.1 1.39 11000 porphyrin a lvalues were calculated by the formula N= 5.54(^/W7)2

Example 8 - Porphyrin separation in slabs

In a method similar to that of example 6, porphyrins were separated on an acetonitrile slab gel of frans-(lS, 2S)-1,2-Bis(dodecylamido)cyclohexane, and the gel was divided into sections for MALDI-MS analysis. A sample from each section was placed onto a MALDI plate with matrix α-cyano-hydroxycinnamic acid. Calibration of the spectrometer with gels containing known concentrations of the porphyins allowed conversion of the signal intensities into concentrations. The resulting electropherograms are shown in Figure 9. Compound 5 is not detected because it is multiply charged, and 1 is not detected because it is too small.

Example 9 - Porphyrin separation with MALDI-TOF-MS interfacing without added matrix

Since porphyrins themselves can act as MALDI matrices, the same experiment as example 8 was performed using no matrix. The resulting electropherogram is shown in Figure 10. Compound 5 is not again not detected because it is multiply charged, but 1 was detected.

Example 10 - Gel Electrophoresis Using Hydrogels

Hydrogels were formed by adding 24 mg of N,N'-dibenzoyl-L-cystine- di(ethanolamide) to 3 niL of buffer, heating until dissolution and casting into the electrophoresis cell. The buffer consisted of 10 mM phosphate (pH 7) in a solution of 15% ethanol in water. A voltage of 500 V was applied for 20 minutes. Amino acids were labeled with dansyl chloride, and non-colored proteins were labeled with 5- carboxyfluorescein, succinimidyl ester. Visualization was carried out by illumination with UV light. The mobilities of the various amino acids and proteins are listed in Table 5. Table 5. Mobility Data for Planar Hydrogels Compound // (10'5 Cm2 V1 S"1

Alanine 10.8 Asparagine 7.2 Aspartic acid 18 Cysteine 7.2 Glutamine 10.4 Glutamic Acid 17.2 Glycine 9.6 Leucine 11.2 Methionine 10.8 Phenylalanine 6.4 Proline 8 Serine 8 Threonine 4.8 Tryptophan 6.4 Tyrosine 4.4 Valine 6.4 Cytochrome C 7.2 Myoglobin 4.8 Peroxidase 8.4 Lactalbumin 4.4 Serum albumin 8.0 Trypsin Inhibitor 7.5 Ovalbumin 2.6 Trypsinogen 4.3 Carbonic Anhydrase 1.4

The results clearly show the ability of the hydrogel to separate analytes such as amino acids and proteins. This illustrates the resolving power of the new matrix and the ability to separate analytes within this gel by capillary electrophoresis. Example 11 - Experimental

Materials. (lS^^-l^-Diaminocyclohexane, lauroyl chloride, dansyl chloride, PEG 200, triethylamine, amino acids, and peptides were purchased from Sigma-Aldrich (St. Louis, MO). Acetic acid was from Frutarom (Haifa, Israel). Ammonium acetate and THF were from Mallinckrodt (Phillipsburg, NJ). Acetonitrile, methanol, and chloroform were from J. T. Baker (Deventer, Holland). BDACH, trans-(\ S, 2S)- l,2-bis(dodecylamido)cyclohexane (1) was synthesized according to the following procedure: Lauroyl chloride (0.768 g, 3.5 mmol) was added to a solution of (lS^Syi^-diaminocyclohexane (0.2 g, 1.75 mmol) and triethylamine (1.77 g, 17.5 mmol) in 50 mL of tetrahydrofuran in a nitrogen atmosphere. The mixture was refluxed for 3 h and allowed to cool. The solvent was removed by rotoevaporation. The remaining solid was dissolved in chloroform and washed in a separatory funnel with water. The solvent was removed, and the product dried in a vacuum desiccator overnight. The product was recrystallized from methanol. Yield: 78%. TLC (9:1 chloroform/ ethyl acetate): Rf ) 0.4. IH NMR (300 MHz, CDC13): S= 5.90 (d, 2H), 3.65 (q, 2H), 2.10 (t, 4H), 1.81-1.49 (m, HH), 1.25 (s, 35H), 0.88 (t, 6H). IR (KBr): v = 3280, 1638, 1549. Elemental analysis calculated (%) for C30H58N2O4 (478.79): C, 75.26; H, 12.21; N, 5.85. Found: C, 74.48; H, 12.12; N, 6.46. Sol-to-gel transition: 55 0C. Dansylation was performed by mixing 0.1 mL of 7.2 niM aqueous amino acid with 1 mL of 10 mM pH 9 carbonate buffer and 0.9 mL of 1 mM dansyl chloride in acetone and heating for 10 min at 70 0C. N,N'-bis(dibenzoyl)-L-cystine-di(ethanolamide) was synthesized as follows: 4g L-cystine and 7.42 g sodium carbonate were dissolved in 200 mL water and 100 mL THF and cooled to 0 0C. 3.72 mL benzoyl chloride was added and the mixture stirred for 6 hours. The reaction mixture was brought to pH 3 with HCl, and N,N'-dibenzoyl-L- cystine precipitated. The intermediate product was filter, washed with water and dried overnight in a vacuum desiccator. Yield: 84%. 3 g dibenzoyl-L-cystine and 1.617 g N- hydroxy succinimide were dissolved in 150 mL dry acetonitrile and cooled to 0 0C. 2.898 g N,N' dicyclohexylcarbodiimide were added and the mixture was stirred overnight at 4 0C. The mixture was brought to room temperature and filtered. The filtrate was cooled to 0 0C and 0.9 mL ethanolamine was added. The precipitated product was collected by filtration and dried in a vacuum desiccator. Yield: 87%. Proteins were stained by dissolving 5 mg of protein in 1 mL aqueous carbonate buffer (pH 9) and adding 0.2 mL of 4mM 5 -carboxy fluorescein, succinimidyl ester (Molecular Probes Inc.) overnight at room temperature.

Instrumentation. Planar electrophoresis experiments were performed in a 12-cm long, 2.6-cm wide Teflon cell. Gel length was 6 cm. Power Λvas supplied by a Consort (Turnhout, Belgium) E862 power supply operating between -200 and -300 V. Gels were formed by adding 6 mg of 1 to 2 mL of buffer, heating until dissolution, and casting into the cell. The buffer was 1 M acetic acid and 25 mM ammonium acetate in acetonitrile or mixtures of acetonitrile with methanol or PEG or lOniM phosphate (pH 7) in 15% ethanol in water. Visual detection was performed with a U"V lamp (Vilber Lourmat 215M, Torcy, France). Experiments were performed in triplicate. Samples for injection into the ESI-MS (LCQ, Finnigan, San Jose, CA) were taken by pushing a plastic grating (4-mm holes with. 1-mm spacing) into the gel and withdrawing the samples with a 10-// L syringe, after gentle stirring for 1 s of the gel in each compartment by the needle of the syringe. The MS was scanned in the ml∑ range of 200-450 in both positive and negative ionization mode. Samples for the MALDI-MS were taken by pushing a plastic grating (1-mm holes xvith 1- nini spacing) into the gel and withdrawing 2 μL with a pipet. Capillary electrophoresis was performed in a Dionex CE instrument with a 42-cm long, 100-//m i.d. capillary (Biotaq, MD). Injection was done electrophoretically. UV detection was carried out at 260 nm for dansyl amino acids and 465 nm for porphyrins. Gel-filled capillaries were made by injecting hot organogel solution (60 0C) into the capillar}' and allowing it to cool. Relative viscosity measurements were made by flowing the solvents through an HPLC system (Finnigan) and measuring the pressure drop through the packed column. Real values were determined by correspondence to reported values of the pure solvents. While the certain embodiments of ttie invention have been illustrated and described, it will be clear that the invention is not limited to the embodiments described herein. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art with-out departing from the spirit and scope of the present invention as described by the claims, which follow.