Plasma fluorinated porous FRIT with sorptive polymer coating for analyte extraction

Abstract

A device and method for extracting analytes from fluid samples using a porous frit composed of sintered plastic polymer particles with a sorptive polymer coating. The frit undergoes plasma fluorination treatment prior to coating application, reducing non-specific binding while enhancing coating adhesion. The sorptive polymer remains above its glass transition temperature at room temperature, enabling analyte diffusion into the bulk polymer rather than surface adsorption. The device integrates into various fluid path configurations and provides rapid three-step sample preparation through extraction, rinse and elution steps. The invention achieves high extraction efficiency and reproducibility across multiple biological matrices while eliminating common problems like clogging and emulsion formation.

Description

PATENT COOPERATION TREATY (PCT) PATENT APPLICATIONPLASMA FLUORINATED POROUS FRIT WITH SORPTIVE POLYMER COATING FOR ANALYTE EXTRACTIONInventor: Thomas Wohleb, Robert Henry Wohleb II, and Robert Henry Wohleb IIICROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 716,032, filed November 4, 2024, entitled "Porous frit coated with polymers above their glass transition temperature," which is incorporated herein by reference in its entirety.FIELD OF THE INVENTION

[0002] The present invention relates generally to sample preparation and analyte extraction devices and methods. More specifically, the invention relates to a porous frit device with a sorptive polymer coating for extracting small molecules from complex biological and aqueous matrices.BACKGROUND OF THE INVENTION

[0003] The analysis of compounds mixed with other compounds presents significant challenges in analytical chemistry. While analyzing individual compounds is relatively straightforward, separating and analyzing compounds from complex mixtures requires multiple steps that introduce potential for error. Each human interaction in the process compounds errors through subsequent steps, creating significant issues by the end of multi-step protocols.

[0004] Current technologies for sample preparation and compound separation face numerous limitations. Traditional solid-phase extraction (SPE) methods rely on surface interactions between a solid phase material and analytes, where analytes are retained on the surface of a solid matrix through hydrogen bonding, van der Waals forces, or ion exchange. The efficiency of these systems depends heavily on surface area, flow rate, and contact time, with sorptive capacity constrained to the external surface.

[0005] Conventional SPE materials require careful conditioning steps with appropriate solvents to remove impurities, activate the sorbent, and optimize retention. A critical limitation is that allowing the SPE material to dry during processing can significantly impact sample preparation results. Additionally, these materials are prone to clogging due to their small particle size (40-60 pm), porosity characteristics, and surface energy properties. These materials further necessitatevacuum or pressure systems for liquid passage, resulting in time-consuming processes that typically take 20-30 minutes to complete. The complexity of these systems limits their automation potential while maintaining relatively high costs. Additionally, method development for SPE systems is lengthy and complex, requiring significant expertise and optimization.

[0006] Prior art approaches have attempted to address these challenges. United States Patent 9,200,991, dated December 1, 2015, which is hereby incorporated by reference in its entirety, describes sorptive extraction layers applied as coatings on interior surfaces of microplate wells. While these non-porous, fixed coatings function within specific analytical formats, they are limited by geometric constraints, low surface area, and lack of modularity. Similarly, US Patent 7,087,437, dated August 8, 2006, which is hereby incorporated by reference in its entirety, discloses a sorptive-coated vial where analytes are extracted through contact with the interior surface of the vial. However, such glass-based, non-porous surfaces are not designed for inline or flow-through use hindering their applicability and effectiveness in a variety of applications.

[0007] Traditional solid-phase extraction (SPE) methods are fundamentally limited by their reliance on surface binding interactions, which constrain extraction efficiency and capacity to the external surface of the solid matrix. A significant challenge in analyzing complex samples is the effective separation of matrix interferences such as proteins, lipids, and enzymes, which can cause ion suppression and deplete analytical sensitivity. Surface interaction mechanisms in SPE often require extensive method development to optimize conditions under which target analytes bind selectively while interferences are minimized — a process that can take months for a single analysis. Existing SPE technologies frequently struggle to rinse away matrix components effectively, leading to inconsistent, irreproducible results.

[0008] A significant limitation exists in the prior art regarding surface treatments for sintered polymer frits used in analyte extraction. While existing patents, including U.S. Patent No.7,887,889, entitled "Plasma fluorination of porous articles using capacitively-coupled discharge systems," issued February 15, 2011, and International Patent Publication No. WO 2003 / 051498, entitled "Plasma treatment to enhance hydrophilicity of porous materials," published June 26, 2003, each of which is hereby incorporated by reference in its entirety, describe plasma treatments for modifying porous surfaces, these approaches fail to address the challenges of nonspecific binding and coating adhesion in analytical applications. Current porous materials suffer from incomplete coating coverage and high background interactions that interfere with accurate analyte detection and quantification. The prior art's focus on hydrophobicity or hydrophilicity modifications for basic filtration and fluid management leaves unaddressed the specific challenges of analyte binding to the base frit substrate, which can reduce extraction efficiency and lead to inconsistent analytical results. Additionally, conventional surface treatments do notadequately solve the problem of polymer coating adhesion to the frit surface, which impacts manufacturing consistency and product reliability. These unresolved challenges in surface modification technology have limited the development of effective sorptive extraction devices that can maintain consistent performance while minimizing unwanted analyte- substrate interactions.SUMMARY OF THE INVENTION

[0009] The present invention in a preferred embodiment provides a revolutionary approach to sample preparation and analyte extraction through a uniquely engineered sorptive extraction device. The invention comprises a porous frit composed of sintered plastic polymer particles that undergoes plasma fluorination treatment prior to being coated with a sorptive polymer that remains above its glass transition temperature at room temperature.

[0010] In one aspect, the invention provides a device for extracting analytes from fluid samples that can be integrated into various fluid path configurations. The device's three-dimensional porous structure enables both convective and diffusive transport of analytes into the sorptive coating under dynamic or static conditions. The porous frit has a pore size range of 10 to 200 microns and an internal surface area of approximately 0.3 square meters per gram, optimizing extraction efficiency while maintaining consistent flow characteristics.

[0011] In another aspect, the invention provides a method of manufacturing the extraction device through plasma fluorination of the frit surface using fluorine-containing gases, followed by application of a sorptive polymer coating using a solvent / anti -solvent system. The plasma treatment serves the dual purpose of reducing non-specific analyte binding while enhancing coating adhesion.

[0012] The invention further provides a simplified three-step extraction process comprising extraction, rinse, and elution steps that can be completed in under two minutes. This represents a significant improvement over traditional 20-30 minute protocols while achieving superior performance.

[0013] Key advantages of the invention include immunity to clogging from complex biological samples, elimination of emulsion formation, and prevention of analyte breakthrough. The device requires no preconditioning steps and enables effective matrix rinsing for clean extracts. The technology demonstrates broad applicability across different analyte types and matrices, successfully extracting a variety of compounds with high reproducibility.BRIEF DESCRIPTION OF THE FIGURES

[0014] FIG. 1 is a cross-sectional view illustrating the internal structure of a sorptive coated frit.

[0015] FIG. 2 depicts a cross-sectional view of a pipette tip, showing the placement of the coated frit within the tip body.

[0016] FIG. 3 presents a cross-sectional view of a cartridge system, such as an SPE cartridge, incorporating the coated frit.

[0017] FIG. 4 shows a cross-sectional view of a spin column device featuring the coated frit at its bottom exit.

[0018] FIG. 5a and FIG. 5b provide schematic top and cross-sectional views, respectively, of a microfluidic device with an integrated coated frit.

[0019] FIG. 6 displays an exploded cross-sectional view of a syringe filter assembly, illustrating the position of the coated frit within the housing.DETAILED DESCRIPTION

[0020] In a preferred embodiment of the invention, a high surface area, low dead volume porous frit is composed of sintered plastic polymer particles. The frit dimensions can vary based on the intended fluid path configuration, ranging from approximately 0.5mm x 1mm for small volume applications like 20pl pipette tips to larger dimensions such as 4.5mm x 6.5mm for standard configurations. The frit may also be conical or otherwise conform to non-standard tubular shapes to match specific flow path requirements. The frit material in this embodiment is formed from sintered polyethylene particles and is plasma treated to be wettable by the polymer coating.

[0021] In an example of the invention, the pore size of the frit is 40 micron with an internal surface area of 0.3 square meters per gram. The sorptive coating is approximately 3 microns thick and covers the entirety of the internal surface area of the frit.

[0022] In an embodiment, the coated frit is inserted into the conus of a 1ml pipette tip and pressed into the area just prior to the tip. The sample preparation process in this embodiment consists of three steps: extraction, rinse, and elution. The extraction is accomplished by aspirating and dispensing a sample three times over a period of 50 seconds. The rinse step is accomplished by aspirating and dispensing a rinse solution once over a period of 20 seconds. The elution step is accomplished by aspirating and dispensing an elution solution three times over a period of 50 seconds.

[0023] In another embodiment of the invention, the sorptive-coated frit may be integrated into various fluid path configurations, including cartridge systems, spin columns, microfluidic devices, and continuous flow-through assemblies. For example, the frit may be inserted intostandard solid-phase extraction (SPE) cartridges or adapted for use in flow-through well plate formats. These configurations enable modular integration of the sorptive frit into both manual and automated sample processing workflows.

[0024] In a preferred embodiment, the sorptive polymer coating is an elastomeric polymer above its glass transition temperature that exhibits the extractive characteristics of a liquid while maintaining complete physical homology. Small molecules are soluble in the extracting phase, allowing partitioning to occur when an aqueous matrix is directly exposed to the polymer. The extracting elastomer is completely immiscible in aqueous sample matrices such as serum, plasma, and urine, which ensures a clean back-extraction when simple preventative measures like rinsing are taken.

[0025] An example implementation demonstrates the extraction of testosterone from human serum using a pipette tip containing the sorptive-coated frit. The process consists of three distinct steps: first, aspirating and dispensing the sample mix three times over a 50-second period; second, performing a single aspiration and dispense cycle with wash solution over 20 seconds; and third, eluting with solvent using three aspiration / dispense cycles over 50 seconds. This method achieves a lower limit of quantitation of 0.04 ng / ml, with excellent linearity and reproducibility.

[0026] In another example, the invention demonstrates extraction of THC metabolites from urine samples, achieving excellent reproducibility with a coefficient of variation of 5.6% and linearity greater than 0.998. Compared to conventional dilute-and-shoot methods, this approach shows reduced matrix effects and improved analyte recovery.

[0027] In a preferred embodiment of the invention, the porous frit is composed of sintered plastic polymer particles, specifically high-density polyethylene or polypropylene. These materials are members of the polyolefin family of polymers, which are polymers produced from simple olefins (alkenes) such as ethylene, propylene, butene, and their copolymers. Throughout this application, the terms "polyolefin" and "polyethylene / polypropylene" may be used interchangeably, with polyolefin serving as the broader polymer classification that encompasses both polyethylene and polypropylene. The frit is formed by sintering or fusing together small particles of these polyolefin materials to create a single unified structure with a consistent porosity profile and mechanical integrity suitable for the intended analytical applications.

[0028] In an example embodiment, the frit is formed from sintered polyethylene particles and has dimensions of approximately 4.5mm*6.5mm. The sintered plastic polymer construction creates an inherent porosity within the frit structure that enables significantly greater surface area compared to non-porous, fixed coatings.

[0029] The sintered plastic polymer composition provides critical advantages for the invention in accordance with a preferred embodiment. Polyolefin materials, such as polyethylene and polypropylene, are inherently chemically inert, minimizing non-specific analyte interactions. However, this inertness also makes direct coating adhesion challenging. Standard oxygen plasma treatments can introduce polar hydroxyl groups onto the surface, increasing hydrophilicity but also creating active sites that may promote undesired analyte binding. In contrast, plasma fluorination modifies the frit surface to enhance polymer adhesion while preserving the material's low surface energy, thereby reducing non-specific interactions. This selective surface modification enables the formation of a uniform sorptive polymer coating while maintaining the base polymer’s desirable chemical inertness.

[0030] In another embodiment, the frit is composed of sintered high-density polyethylene particles that are plasma treated to be wettable by the polymer coating that will be subsequently applied. The sintered construction creates a three-dimensional structure with interconnected pores throughout the frit body, enabling both convective and diffusive transport of analytes.

[0031] The sintered plastic polymer composition is specifically chosen to be non-glass based, utilizing instead thermoplastic polymeric materials that can be effectively modified through plasma treatment. This composition allows the frit to maintain its structural integrity while providing an appropriate substrate for the sorptive coating.

[0032] In a preferred embodiment of the invention, the porous frit has a pore size range of 10 to 200 microns, which enables optimal flow characteristics and extraction efficiency.

[0033] In an example embodiment, the frit is constructed with a pore size of 40 micron, which provides an internal surface area of 0.3 square meters per gram. This specific pore size allows for efficient convective and diffusive transport of analytes into the sorptive coating under both dynamic and static conditions.

[0034] The selected pore size range is critical for optimizing extraction performance in accordance with various embodiments. Sufficient porosity ensures a high surface area for sorptive polymer coating while maintaining low dead volume, which improves the phase ratio between the polymer phase and the fluid sample and enhances mass transfer rates. Excessively small pores or thick polymer coatings can hinder analyte diffusion into the sorptive phase, slowing extraction kinetics and reducing sensitivity. Maintaining an appropriate pore structure thus enables rapid analyte partitioning into the coating while minimizing fluidic resistance and non-productive sample volume.

[0035] In another embodiment, the pore size range enables reproducible, conformal internal coating throughout the frit geometry. The porous structure with defined pore sizes allows for effective mass transfer, as the rate of diffusion of an analyte within the sample, across theinterface, or within the immobilized liquid is directly proportional to the absolute temperature and inversely proportional to the square root of the molecular weight.

[0036] The 10-200 micron pore size range also facilitates continuous flow-through operation while maintaining structural integrity. This range has been optimized based upon considerations of coating thickness, dead volume, and sample volume such that extraction time, efficiency, and phase ratio are maximized. The pore structure enables both convective mass transport during analyte extraction and effective rinsing of matrix interference components.

[0037] In a preferred embodiment of the invention, the porous frit has an internal surface area of 0.3 square meters per gram, which provides sufficient surface area for effective analyte extraction while maintaining optimal phase ratios.

[0038] The internal surface area specifications in accordance with a preferred embodiment are critical to achieving efficient analyte extraction. In one embodiment, the available surface area is optimized relative to the polymer coating thickness to maintain an effective phase ratio and to promote rapid diffusion of analytes into the sorptive layer. If surface area is insufficient relative to coating thickness, the polymer phase can become saturated at the surface, requiring analytes to diffuse deeper into the coating to reach available sorptive sites. This increases diffusion pathlengths, slows extraction kinetics, and reduces overall analytical performance. Therefore, balancing surface area and coating thickness is essential for maximizing extraction speed and capacity.

[0039] In another embodiment, the internal surface area specifications are designed to provide the same amount of polymer but with more surface area to make the functioning more efficient. The very low dead volume and high surface area are critically important in the context of the invention because of phase ratio and rate of diffusion through the polymer.

[0040] The internal surface area specifications work in conjunction with the three-dimensional geometry of the frit to enable convective mass transport during analyte extraction. This combination of specified internal surface area and geometric structure allows for both convective and diffusive transport of analytes into the sorptive coating under dynamic or static conditions.

[0041] In a preferred embodiment, the internal surface area specifications are optimized based upon considerations of coating thickness, dead volume, and sample volume such that extraction time, efficiency, and phase ratio are maximized. The specified surface area enables reproducible, conformal internal coating throughout the frit geometry while maintaining sufficient capacity for analyte extraction.

[0042] In a preferred embodiment of the invention, the three-dimensional geometry of the porous frit enables both convective and diffusive transport of analytes into the sorptive coating under dynamic or static conditions.

[0043] The three-dimensional structure is created through the sintering process which fuses the polymer particles together to form interconnected pores throughout the frit body. This geometry is critical because it allows for convective mass transport during analyte extraction while maintaining a high surface area relative to flat coatings.

[0044] In an embodiment, the three-dimensional geometry works in conjunction with the specified pore size range and internal surface area to optimize mass transfer. The overall kinetics of extraction are controlled by the characteristics of the device and coating that affect mass transfer. Mass transfer occurs through the net movement of analytes from the sample to the immobilized liquid, accomplished by the diffusion process within the sample, between the sample and immobilized liquid, and within the immobilized liquid until equilibrium is reached.

[0045] The three-dimensional structure provides several key advantages. In a preferred embodiment, the geometry enables rapid diffusion in the immobilized liquid due to small diffusion distances relative to the sample. Changes in surface area have a profound effect on kinetics, as increasing the surface area of the immobilized liquid increases the rate of diffusion across the interface directly proportional to the surface area. The concomitant reduction in diffusion distance within the sample therefore reduces the time to equilibrium.

[0046] In another embodiment, the three-dimensional geometry facilitates flow-through operation while maintaining structural integrity. The structure allows for effective rinsing of matrix interference components while providing sufficient surface area for the sorptive polymer coating. This geometric configuration has been optimized based upon considerations of coating thickness, dead volume, and sample volume such that extraction time, efficiency, and phase ratio are maximized.

[0047] In a preferred embodiment of the invention, the surface treatment process comprises the following methods and associated steps:

[0048] Conducting plasma fluorination by exposing the frit to plasma generated from fluorine-containing gases in a capacitively-coupled discharge system. The plasma treatment modifies the surface energy of the polyolefin frit to enable proper wetting and adhesion of the subsequent polymer coating.

[0049] In an exemplary embodiment, the fluorine-containing gases may include, but are not limited to, tetrafluoromethane (CF4), sulfur hexafluoride (SFe), hexafluoroethane (C2F6), perfluoropropane (CsFs), hexafluor opr opylene (CsFe), octafluorocyclobutane (C4F8), and other fluorine-containing compounds. These gases may be used individually or in combination toachieve the desired surface modification effects. The specific gas selection affects the degree of fluorination and resulting surface properties in accordance with various embodiments. The fluorine-containing compounds should be capable of generating reactive fluorine species under plasma conditions and have appropriate physical properties for use under plasma treatment conditions.

[0050] Incorporating oxygen or other reactive gases optionally with the fluorine-containing gases during plasma treatment. This combination enhances surface modification and allows precise control over the surface energy characteristics in accordance with a preferred embodiment. The addition of reactive gases helps optimize the interface between the frit substrate and polymer coating by reducing analyte interaction with the frit substrate and enhancing coating adhesion through surface energy modification.

[0051] In a preferred embodiment of the invention, the plasma fluorination process parameters comprise specific operating conditions for achieving reproducible surface modification. The plasma treatment is conducted in a capacitively-coupled discharge system at a chamber pressure between 0.1-1.0 Torr and RF power settings of 50-500 watts. The exposure time is maintained between 30-300 seconds to achieve optimal surface modification while preventing degradation of the base polymer.

[0052] The chamber conditions in another embodiment are controlled to maintain plasma stability, with the fluorine-containing gas flow rate regulated between 10-100 standard cubic centimeters per minute (seem). When oxygen or other reactive gases are included, they are introduced at 5-25% of the total gas flow rate. The chamber temperature is maintained below 50°C during treatment to prevent thermal damage to the polymer frit.

[0053] In a preferred embodiment, the plasma treatment parameters are verified through surface wettability measurements. Because plasma-fluorinated surfaces are highly hydrophobic and chemically distinct from surfaces treated with oxygen-based plasmas, a test solution chemically analogous to the sorptive polymer formulation is used to evaluate wetting behavior. The process parameters are adjusted to achieve optimal surface compatibility for subsequent coating adhesion, as indicated by consistent wetting of the polymer solution across the frit surface. Contact angle measurements using the sorptive polymer solution should demonstrate angles less than 45 degrees, confirming effective surface modification and wetting properties. Modifying surface energy through plasma fluorination produces several key effects. The process introduces fluorinated chemical groups, such as carbon-fluorine (C-F) and fluorocarbon (CFX) functionalities, onto the surface of the sintered polymer frit. These modifications reduce surface energy and enhance hydrophobicity while also improving the adhesion of subsequently applied polymer coatings. In certain plasma conditions, localized surface etching and mild crosslinkingmay also occur, leading to increased surface roughness (rugosity) that further promotes mechanical interlocking of coatings. This combination of chemical and topographical changes enables consistent, uniform polymer deposition while minimizing non-specific analyte interactions with the base material.

[0054] In an exemplary embodiment, the surface energy modification serves dual purposes by reducing non-specific analyte binding to the base frit substrate while enhancing polymer coating adhesion. The modified surface enables reproducible, conformal coating throughout the internal frit geometry.

[0055] Plasma fluorination of the frit surface optimizes wetting conditions for the subsequent sorptive polymer coating. Although plasma fluorination generally lowers absolute surface energy compared to oxygen-based plasma treatments, it introduces fluorinated chemical groups that are chemically compatible with low-surface-energy polymers, such as polydimethylsiloxane. This chemical affinity promotes uniform wetting and spreading of the sorptive coating across the frit structure. Wetting performance can be quantitatively assessed using contact angle measurements between the sorptive polymer solution and the plasma-treated frit surface, where improved wetting is indicated by a lower contact angle. Plasma-fluorinated surfaces are highly hydrophobic and chemically distinct from standard high-energy surfaces. A wetting solution chemically analogous to the sorptive polymer formulation is used to verify proper surface modification and predict coating adhesion in accordance with various embodiments of the invention. The plasma fluorination process produces a surface that maintains complete physical homology while exhibiting enhanced coating adhesion properties. This allows the subsequent polymer coating to function as an immobilized liquid that remains completely immiscible in aqueous sample matrices, ensuring clean back-extraction when simple preventative measures are taken.

[0056] In a preferred embodiment of the invention, the sorptive polymer coating comprises specific characteristics that enable effective analyte extraction. The coating is composed of an elastomeric polymer that remains above its glass transition temperature at room temperature, allowing it to exhibit the extractive characteristics of a liquid while maintaining complete physical homology.

[0057] In an embodiment, the sorptive polymer is selected from the group consisting of polydimethylsiloxane (PDMS), polybutadiene, siloxane copolymers, polydivinylbenzene (PDVB), polyurethane elastomers, polyacrylates, polymethacrylates, polyacrylonitrile-based copolymers, cyano-functionalized polymers, flexible phenol-functionalized copolymers, polymeric ionic liquids (PILs), polycaprolactone (PCL), fluorinated polymer copolymers, polyethylene-co-polypropylene copolymers, polystyrene-butadiene copolymers (SBS), andethylene-propylene-diene monomer (EPDM) rubbers. These polymers are selected for their ability to remain above their glass transition temperature at room temperature, allowing efficient analyte partitioning while maintaining phase stability. They are substantially immiscible with aqueous media such as serum, plasma, and urine, enabling consistent, reproducible extraction performance in biological matrices. Other alternative polymers bearing similar characteristics may be utilized in embodiments of the invention.

[0058] In varying embodiments of the invention, an alternative polymer that remains above its glass transition temperature at room temperature and exhibits the extractive characteristics of a liquid while maintaining complete physical homology may be used as the sorptive coating. Such polymers function as immobilized liquids that allow small molecules to partition into the extracting phase while remaining completely immiscible in aqueous sample matrices. This enables clean back-extraction when appropriate preventative measures are taken. The polymer's ability to maintain complete physical homology while exhibiting liquid-like diffusion characteristics is critical for achieving consistent extraction performance across diverse analytical applications.

[0059] The coating thickness in a preferred embodiment is approximately 3 microns, applied uniformly across the internal surface area of the frit. This specific thickness is optimized to provide sufficient sorptive capacity while maintaining rapid diffusion kinetics. If the coating is too thick, the surface becomes loaded and analytes must move through the polymer before more can be added, which slows down the extraction process.

[0060] In another embodiment, the polymer coating exhibits specific glass transition temperature requirements, remaining above its glass transition temperature at room temperature to enable efficient analyte uptake. The most useable immobilized liquid polymers are those that exhibit an open morphology and have a backbone that easily rotates, typically requiring a glass transition temperature below 0° centigrade with minimal crosslink density.

[0061] The surface coverage parameters are critical for performance. In a preferred embodiment, the coating provides complete coverage of the internal frit surfaces while maintaining the porous structure. Small molecules are soluble in the extracting phase, allowing partitioning to occur when an aqueous matrix is directly exposed to the polymer. The non-porous nature of the immobilized liquid coating eliminates problems often encountered with existing methods such as the formation of emulsions, analyte breakthrough, and clogging.

[0062] In a preferred embodiment of the invention, the coating application process comprises applying the sorptive polymer using a mixed solvent / anti- solvent system through the following method and associated steps:

[0063] Preparing the coating solution by dissolving the sorptive polymer in a solvent to form a primary solution, then adding an anti-solvent in an amount sufficient to reduce the solubility of the polymer while maintaining a metastable single-phase solution.

[0064] Applying the coating solution to the plasma-fluorinated frit, allowing the polymer to precipitate during solvent and anti-solvent evaporation as a conformal coating. The evaporation is performed at ambient temperature or under mild heat below 50°C to control the rate of polymer deposition.

[0065] Selecting solvents and anti-solvents wherein the solvent is chosen from hydrocarbons, ethers, esters, or alcohols, and the anti-solvent is selected from water, alkanes, or short-chain alcohols. The anti-solvent is specifically selected to lower the solubility of the sorptive polymer without inducing immediate precipitation prior to evaporation.

[0066] In an embodiment, the plasma fluorination alters surface energy to facilitate uniform coating via the solvent / anti -solvent system. This surface modification enables reproducible, conformal internal coating throughout the frit geometry.

[0067] The coating process produces a thin layer approximately 3 microns thick that covers the entirety of the internal surface area of the frit. The process is optimized to achieve complete coverage while maintaining the porous structure and flow characteristics of the frit.

[0068] In another embodiment, the coating process includes stabilization or curing steps to ensure proper adhesion and coating integrity. The process parameters are controlled to achieve batch consistency and coating uniformity across production runs. Quality control testing verifies proper coating thickness, uniformity, and adhesion to the plasma-treated frit surface.

[0069] In a preferred embodiment of the invention, the solvent / anti -solvent system comprises specific solvents selected to achieve optimal polymer deposition and coating uniformity. The solvent is selected from the group consisting of hydrocarbons, ethers, esters, or alcohols, while the anti-solvent is selected from water, alkanes, or short-chain alcohols.

[0070] The process involves dissolving the sorptive polymer in a solvent to form a primary solution, then adding an anti-solvent in an amount sufficient to reduce the solubility of the polymer while maintaining a metastable single-phase solution. The anti-solvent is specifically selected to lower the solubility of the sorptive polymer without inducing immediate precipitation prior to evaporation.

[0071] In an embodiment, the polymer precipitates during solvent and anti-solvent evaporation as a conformal coating. The evaporation is performed at ambient temperature or under mild heat below 50°C to control the rate of polymer deposition, allowing the sorptive polymer to precipitate as a uniform coating on internal and external surfaces of the frit.

[0072] The plasma fluorination treatment of the frit surface enhances the effectiveness of the solvent / anti -solvent system by altering surface energy to facilitate uniform coating. This surface modification enables reproducible, conformal internal coating throughout the frit geometry.

[0073] In a preferred embodiment of the invention, the solvent / anti -solvent coating system comprises specific ratios and parameters for achieving consistent coating properties. The primary solution is prepared with a polymer concentration of 0.5-5.0% w / v in the solvent phase. The anti-solvent is added in a ratio of 1 :2 to 1 :4 relative to the primary solution while maintaining a metastable single-phase system.

[0074] For elastomeric polymers like AEM copolymers, the primary solvent comprises a mixture of hydrocarbons, ethers, or esters, with the anti-solvent selected from water or shortchain alcohols. The critical polymer concentration range is maintained between 1-3% w / v to achieve proper coating viscosity and thickness control.

[0075] The process parameters for achieving the specified 3-micron coating thickness include carefully controlled deposition conditions. The coating solution is applied at room temperature (20-25°C) with controlled relative humidity below 60%. The evaporation rate is regulated through mild heating at 30-45°C while maintaining laminar airflow conditions.

[0076] Quality control measurements verify coating thickness using microscopic examination of cross-sections and gravimetric analysis. The coating weight per unit surface area is maintained within ±10% of the target specification across the internal frit geometry.

[0077] In a preferred embodiment, the solvent / anti-solvent ratios and evaporation conditions are controlled to achieve consistent coating thickness of approximately 3 microns across the internal surface area of the frit. The system enables complete coverage while maintaining the porous structure and flow characteristics of the frit.

[0078] In a preferred embodiment of the invention, the solution preparation methods comprise specific steps for creating the coating solution. The process begins by dissolving the sorptive polymer in a primary solvent selected from hydrocarbons, ethers, esters, or alcohols to achieve complete dissolution.

[0079] In an embodiment, the solution preparation includes careful control of polymer concentration and solvent ratios to achieve optimal coating properties. The anti-solvent is added in precise amounts to reduce polymer solubility while maintaining a metastable single-phase solution. This balance is critical as the anti-solvent must lower the solubility of the sorptive polymer without causing immediate precipitation.

[0080] The solution preparation process requires controlling temperature and mixing conditions to ensure uniform polymer distribution. In a preferred embodiment, the polymer solution isprepared at ambient temperature or under mild heating conditions below 50°C to maintain solution stability while enabling proper coating deposition.

[0081] For commercial pre-polymers used in solution preparation, the process includes polymer fractionation and cleaning steps. The pre-polymers typically have a large molecular weight dispersion range that must be controlled. Smaller molecular weight fractions that lack sufficient crosslinking functionality are eliminated to prevent them from becoming extractable components in the final product.

[0082] In a preferred embodiment of the invention, the polymer cleaning and fractionation process comprises specific methods for removing low molecular weight components and processing aids from commercial pre-polymers. The fractionation process begins by dissolving the pre-polymer in a suitable solvent at 1-5% concentration by weight. The solution is then subjected to selective precipitation using an anti-solvent to remove low molecular weight fractions that lack sufficient crosslinking functionality.

[0083] In an embodiment, the fractionation is conducted through controlled addition of the antisolvent while maintaining the temperature between 20-30°C. The precipitated high molecular weight fraction is collected by filtration or centrifugation, while the low molecular weight components remain in solution. This process may be repeated multiple times to achieve the desired molecular weight distribution.

[0084] The removal of processing aids in a preferred embodiment is accomplished through washing steps using appropriate solvents. For AEM copolymers, the polymer is washed sequentially with methanol and acetone to remove processing aids while maintaining the polymer's physical properties. The washing process continues until spectroscopic analysis confirms removal of processing aid components.

[0085] In another embodiment, the cleaned and fractionated polymer is dried under vacuum at temperatures below 50°C until constant weight is achieved. The final product is analyzed for molecular weight distribution using gel permeation chromatography to verify removal of low molecular weight fractions. The cleaned polymer should contain less than 1% of components below the critical molecular weight for entanglement.

[0086] In another embodiment, the solution preparation includes removal of processing aids and other contaminants from the pre-polymers prior to coating solution formulation. This cleaning step is essential as these components are considered contamination in the final product and must be eliminated to ensure coating quality and performance.

[0087] In a preferred embodiment of the invention, the application techniques for the sorptive polymer coating comprise specific methods for achieving uniform coverage of the frit surface.The coating is applied to the plasma-treated frit using controlled dispensing of the polymer solution, allowing even distribution throughout the porous structure.

[0088] In an embodiment, the application process involves carefully controlling the coating environment temperature and conditions. The evaporation is performed at ambient temperature or under mild heat below 50°C to control the rate of polymer deposition and achieve uniform coating formation.

[0089] The application technique in a preferred embodiment utilizes the modified surface energy from plasma fluorination to facilitate uniform coating via the solvent / anti-solvent system. This surface modification enables reproducible, conformal internal coating throughout the frit geometry while maintaining the porous structure.

[0090] In another embodiment, the coating is applied by allowing the polymer to precipitate during controlled evaporation of the solvent and anti-solvent, forming a uniform coating on both internal and external surfaces of the frit. The precipitation process is carefully managed to achieve a coating thickness of approximately 3 microns across the entirety of the internal surface area.

[0091] The application technique includes verification steps to ensure proper coating coverage and uniformity. In a preferred embodiment, the coating process is monitored to confirm complete coverage of the internal frit surfaces while maintaining the porous structure and flow characteristics. The non-porous nature of the applied coating eliminates problems often encountered with existing methods such as emulsion formation, analyte breakthrough, and clogging.

[0092] In a preferred embodiment of the invention, the evaporation and curing conditions are carefully controlled to achieve optimal coating properties. The evaporation is performed at ambient temperature or under mild heat below 50°C to control the rate of polymer deposition, allowing the sorptive polymer to precipitate as a uniform coating on internal and external surfaces of the frit.

[0093] In an embodiment, the evaporation conditions are managed to maintain a metastable single-phase solution until the coating process is complete. The anti-solvent is selected to lower the solubility of the sorptive polymer without inducing immediate precipitation prior to evaporation, enabling controlled deposition of the coating.

[0094] For elastomeric polymers like AEM copolymers, the curing conditions can be controlled through either peroxide free radical systems or primary diamine vulcanization. In a preferred embodiment using AEM terpolymers, the vulcanization requires an extensive cure and post cure to complete the reaction and convert amide cross links to imide crosslinks.

[0095] In a preferred embodiment of the invention, the vulcanization and curing processes for elastomeric polymers comprise specific conditions and parameters for achieving optimal crosslinking. For AEM copolymers, the vulcanization can be controlled through either peroxide free radical systems or primary diamine vulcanization.

[0096] In an embodiment using AEM terpolymers, the vulcanization process requires specific temperature and time parameters. The initial cure is conducted at temperatures not exceeding 110°C to remain below the melting point of the high-density polyethylene frit material (approximately 130°C). The curing process is conducted for approximately 4 hours to achieve proper crosslinking.

[0097] The vulcanization and curing conditions in accordance with an embodiment must be carefully controlled to prevent degradation of the frit substrate while ensuring proper polymer crosslinking. The temperature parameters are specifically selected to maintain the structural integrity of the polyethylene frit while achieving adequate polymer curing.

[0098] For AEM copolymers in a preferred embodiment, the free radical crosslinking system targets the most labile hydrogen on the acrylate group, though some chain formation also occurs across the ethylene segments. The process requires careful control of peroxide concentration and cure temperature to achieve optimal crosslink density while maintaining the polymer's physical properties.

[0099] The shelf stability of the cured polymers in a preferred embodiment is excellent, being measured in years. The cured polymers maintain their rubber-like qualities for extended periods, with useful life varying based on exposure temperature. At 121°C, the approximate useful life is two years, decreasing to 5 days at 204°C.

[0100] In another embodiment, the evaporation and curing conditions are optimized to achieve a coating thickness of approximately 3 microns while maintaining complete coverage of the internal frit surfaces. The process parameters ensure the non-porous nature of the immobilized liquid coating, which eliminates problems often encountered with existing methods such as emulsion formation and analyte breakthrough.

[0101] In a preferred embodiment of the invention, the pipette tip implementation comprises specific requirements for integrating the coated frit into standard pipette tips. The frit is inserted into the conus of a 1ml pipette tip and pressed into the area just prior to the tip transition point.

[0102] The insertion specifications in an embodiment require precise positioning of the cylindrical porous frit with dimensions of 4.5mm*6.5mm. The frit is stuffed into a pipette tip, creating an extraction device that maintains proper flow characteristics while enabling effective sample preparation.

[0103] In a preferred embodiment, the positioning requirements ensure the frit is securely placed at the tip transition point. This specific positioning is critical for maintaining proper flow paths and enabling consistent extraction performance. The frit must be pressed firmly into position to prevent any bypass flow around the edges.

[0104] The flow path considerations in an embodiment focus on optimizing the three-dimensional geometry to enable both convective and diffusive transport of analytes into the sorptive coating under dynamic and static conditions. The positioning and dimensions of the frit are designed to maintain low dead volume while providing sufficient surface area for extraction.

[0105] In another embodiment, the flow path design enables a simplified three-step workflow: extraction, rinse, and elution. The extraction is accomplished by aspirating and dispensing a sample three times over 50 seconds, followed by rinsing with a wash solution for 20 seconds, and eluting with solvent using three aspiration / dispense cycles over 50 seconds.

[0106] The implementation in a preferred embodiment allows for integration with both manual and automated liquid handling systems. The device maintains consistent performance across multiple aspiration and dispense cycles while preventing issues like clogging or emulsion formation that are common with traditional extraction methods.

[0107] In a preferred embodiment of the invention, the frit insertion process comprises specific methods and parameters for achieving proper positioning and sealing. The cylindrical porous frit with dimensions of 4.5mm*6.5mm is inserted into the conus of a 1ml pipette tip using controlled force to achieve precise positioning at the tip transition point.

[0108] The positioning requirements in a preferred embodiment specify that the frit must be pressed firmly into the area just prior to the tip transition point. The insertion depth is controlled to ensure the frit creates a compression seal against the internal walls of the pipette tip conus while maintaining proper flow path geometry. This specific positioning prevents any bypass flow around the edges while enabling both convective and diffusive transport of analytes.

[0109] In another embodiment, the sealing parameters are verified through flow resistance testing. The properly sealed frit demonstrates consistent flow resistance within ±15% of specification when tested with standard solutions. The compression fit creates a fluid-tight seal between the frit's outer diameter and the pipette tip's inner wall, preventing any sample from bypassing the sorptive coating.

[0110] Quality control measures in a preferred embodiment include visual inspection of frit positioning using calibrated measurement tools to verify proper insertion depth. Flow path testing confirms uniform sample distribution across the frit cross-section without channeling or bypass. Each assembled device undergoes leak testing using pressurized air or liquid to verify seal integrity.

[0111] The assembly process in another embodiment includes verification of proper frit orientation to maintain optimal flow characteristics. The frit's cylindrical geometry must be properly aligned with the pipette tip axis to ensure uniform sample contact with the sorptive coating. Quality control testing confirms consistent extraction performance across multiple aspiration and dispense cycles, demonstrating proper frit positioning and sealing.

[0112] In a preferred embodiment of the invention, the coated frit can be integrated into various device implementations beyond pipette tips. For cartridge systems, the frit may be incorporated into standard SPE cartridges along with flow through well plates. The cartridge implementations include luer tip or luer lock fittings for secure connections.

[0113] In an embodiment utilizing spin columns, the sorptive frit is placed at the bottom exit of the device. The spin column configuration enables centrifugation-based sample processing while maintaining the extraction capabilities of the coated frit.

[0114] For microfluidic device implementations, the invention can be integrated into lab-on-chip or other microfluidic systems. The three-dimensional geometry and flow characteristics of the coated frit enable effective integration into microfluidic channels while maintaining extraction performance.

[0115] In a preferred embodiment, the flow-through configurations include filter funnels and other continuous flow devices. These implementations maintain the porous and flow-through operation capabilities of the frit while enabling convective mass transport during analyte extraction.

[0116] The device implementations in another embodiment include cartridge, syringe, or analytical flow cell configurations. The frit is manufactured as a modular plug-in compatible with standard fluidic connections, enabling integration into disposable or automated sampling systems.

[0117] For filter well plate implementations, various filtration components may be incorporated into the device according to different embodiments of the invention. In one exemplary embodiment, prefilter and membrane components are replaced by the sorptive filter frit. More broadly, the invention contemplates the use of any suitable filtration element or combination of elements that can be integrated into filter well plates, including but not limited to frits, membranes, filters, or combinations thereof. Regardless of the specific filtration components employed, the configuration maintains proper flow characteristics while enabling effective sample preparation through the three-step extraction, rinse, and elution process.

[0118] In a preferred embodiment of the invention, the sample preparation parameters are optimized for effective analyte extraction. The sample preparation may involve combining an extraction mix with a biological sample in proportions that facilitate optimal extractionefficiency. In an exemplary embodiment, the total sample volume is approximately 200pl, which may comprise approximately 150pl of extraction mix combined with approximately 50pl of serum or other biological sample. However, the invention contemplates a range of sample volumes and ratios that may be optimized based on the specific analyte, matrix, and analytical requirements of a particular application.

[0119] In another embodiment, the sample preparation includes combining a modifier buffer with a sample in a ratio that optimizes extraction conditions. The ratio between modifier buffer and sample may vary depending on analyte properties, matrix complexity, and desired analytical performance. As an example, one implementation may utilize approximately lOOpl of modifier buffer combined with approximately lOOpl of sample. The modifier buffer typically contains internal standards and pH modifiers to optimize extraction conditions, with the specific composition tailored to the requirements of the target analytes and sample matrices.

[0120] Matrix compatibility in a preferred embodiment extends to various biological fluids including blood, plasma, serum, urine, sputum and other liquid matrices. The extracting elastomer is completely immiscible in these aqueous sample matrices, which ensures clean back-extraction when appropriate rinsing steps are performed.

[0121] The invention demonstrates matrix compatibility through successful extraction of testosterone from human serum with a lower limit of quantitation of 0.04 ng / ml, THC metabolites from urine with excellent reproducibility achieving a coefficient of variation of 5.6%, and Vitamin D metabolites from serum with high accuracy of ±10% and precision with coefficient of variation less than 9%.

[0122] The analyte requirements in a preferred embodiment specify compounds with LogP greater than 1, indicating sufficient hydrophobicity for effective extraction. The extraction process is particularly effective for small organic molecules from complex aqueous matrices. The partition ratio of an analyte for the extraction phase compared to water can be predicted based on the compound's LogP value, allowing for estimation of extraction efficiency.

[0123] The invention demonstrates successful extraction across a range of LogP values, including testosterone with LogP 3.365, THC-COOH with LogP 5.14, and 25-OH- Vitamin D2 with LogP 7.051, showing broad applicability across different analyte types.

[0124] In a preferred embodiment of the invention, the operating procedures comprise specific extraction, rinse and elution steps. The extraction step involves aspirating and dispensing the sample mixture three times over 50 seconds. This extraction timing allows analytes to partition into the sorptive coating to reach equilibrium.

[0125] In another embodiment, the extraction process involves aspirating and dispensing a sample three times over a period of 20 seconds to achieve optimal extraction efficiency. Thetiming and number of cycles are critical for allowing sufficient contact between the sample and the sorptive coating while maintaining practical throughput.

[0126] The rinse protocol in a preferred embodiment comprises aspirating and dispensing a wash solution once over 20 seconds. The wash solution typically contains appropriate modifiers to remove residual matrix components while maintaining analyte retention. For example, when extracting testosterone from serum, the wash solution contains 0.2% formic acid in water.

[0127] In an embodiment for vitamin D metabolite extraction, the rinse step uses water / methanol (90:10 v / v) as the wash solution. This composition enables effective removal of matrix interference components without significant analyte loss.

[0128] The elution methods in a preferred embodiment involve aspirating and dispensing an elution solvent three times over 50 seconds. The elution solvent composition is optimized based on analyte properties. For THC metabolites, the elution uses water / acetonitrile (15 / 85 v / v) with 0.2% formic acid.

[0129] In another embodiment demonstrating the elution process, the eluted sample is transferred directly to an autosampler vial or plate fitted with a pierceable cover to minimize solvent evaporation. The eluate is then placed in a cooled autosampler (10°C) for immediate analysis by LC-MSMS.

[0130] In a preferred embodiment of the invention, the performance characteristics demonstrate exceptional extraction efficiency and analytical performance. The extraction efficiency for testosterone and 13 C3 -testosterone using the IFX Extraction Tip method achieves 53 and 55% recovery respectively.

[0131] The IFX Extraction Tip is a pipette tip containing a porous frit that has been plasma fluorinated and coated with a sorptive polymer for extracting small molecules from biological samples. The device consists of a frit with dimensions of approximately 4.5mm*6.5mm that is inserted into the conus of a 1ml pipette tip and pressed into the area just prior to the tip transition point. The frit is internally coated with a sorptive phase that functions like an immobilized liquid, allowing analytes to partition into the polymer coating rather than simply adsorbing to the surface. The extraction process using the IFX Extraction Tip follows a simple three-step workflow: aspirating and dispensing the sample three times over 50 seconds for extraction, performing a single rinse step over 20 seconds, and eluting with solvent through three aspiration / dispense cycles over 50 seconds. This device enables efficient sample preparation while eliminating common problems like clogging, emulsion formation, and analyte breakthrough that are typically encountered with traditional extraction methods.

[0132] In an embodiment demonstrating reproducibility, the extraction and analysis of testosterone from serum calibrators shows excellent consistency with coefficient of variationranging from 1.0 to 8.3% for peak areas. The internal standard areas demonstrate high reproducibility with CV values between 1.0 and 7.5%.

[0133] Matrix effects in a preferred embodiment are effectively minimized, with testosterone extraction from serum samples showing only negligible ionization enhancement of 103%. This demonstrates the effectiveness of the rinse step in removing matrix interference components.

[0134] The analytical parameters in another embodiment show exceptional sensitivity and precision. For testosterone analysis, the lower limit of quantitation (LLOQ) is established at 0.04 ng / ml, with signal-to-noise ratio greater than 10. For THC-COOH analysis, the LLOQ is achieved at 2.5 ng / ml with excellent reproducibility.

[0135] In a preferred embodiment, the linear range demonstrates outstanding performance across multiple applications. Testosterone analysis shows linearity from 0.04 to 10 ng / ml with correlation coefficient (r2) greater than 0.998. THC-COOH analysis demonstrates linearity between 2.5 and 100 ng / ml with correlation coefficient (r) greater than 0.998.

[0136] The precision specifications in another embodiment show high reproducibility across different applications. For vitamin D metabolite analysis, high accuracy of ±10% and precision with CV less than 9% are achieved across calibration levels. Batch-to-batch variation analysis of antidepressants in plasma demonstrates average CV of approximately 5% across ten batches of 100 inserts each.

[0137] In a preferred embodiment of the invention, the manufacturing considerations include specific quality control parameters and production specifications. The batch consistency requirements demonstrate high reproducibility, with batch-to-batch variation analysis showing average coefficient of variation of approximately 5% across ten batches of 100 extraction devices.

[0138] In a preferred embodiment of the invention, the quality control testing methods comprise specific procedures for verifying coating properties and consistency. The coating uniformity testing includes microscopic examination of cross-sections and gravimetric analysis to verify the coating weight per unit surface area is maintained within ±10% of target specifications across the internal frit geometry. Surface coverage is confirmed through scanning electron microscopy to ensure complete coating of internal surfaces while maintaining the porous structure.

[0139] In another embodiment, batch consistency requirements specify acceptance criteria for manufacturing validation. Each production batch undergoes extraction efficiency testing using standard analytes, with acceptance requiring recovery rates within ±10% of established specifications. Reproducibility testing demonstrates coefficient of variation less than 10% for internal standard peak areas across multiple extractions. Batch-to-batch variation analysisrequires average coefficient of variation of approximately 5% across ten batches of 100 extraction devices.

[0140] The quality control process in a preferred embodiment includes verification of coating thickness using multiple measurement techniques. Cross-sectional analysis confirms the 3-micron target thickness is maintained within ±0.5 microns. Flow resistance measurements verify consistent pore structure and coating uniformity, with acceptance criteria requiring less than 15% variation in flow rates across the batch. Each production batch undergoes matrix effect testing using standard biological samples, with acceptance requiring ionization enhancement or suppression within ±5% of established specifications.

[0141] The coating uniformity testing in an embodiment includes verification of complete coverage across internal frit surfaces while maintaining porous structure. The coating thickness is verified to be approximately 3 microns across the entirety of the internal surface area. Quality control testing confirms proper coating adhesion to the plasma-treated frit surface.

[0142] In a preferred embodiment, the frit dimensional tolerances specify a cylindrical porous frit with dimensions of 4.5mm*6.5mm. These dimensions are critical for proper insertion into the pipette tip conus and maintaining appropriate flow characteristics.

[0143] The coating process controls in another embodiment include careful management of the solvent / anti -solvent system. The evaporation is performed at ambient temperature or under mild heat below 50°C to control polymer deposition rate. The anti-solvent concentration is controlled to reduce polymer solubility while maintaining a metastable single-phase solution.

[0144] Assembly requirements in a preferred embodiment specify insertion of the coated frit into the conus of a 1ml pipette tip, with precise positioning at the tip transition point. The frit must be pressed firmly into position to prevent bypass flow while maintaining proper flow path characteristics. The assembly process ensures the device is compatible with both manual and automated liquid handling systems.

[0145] The present invention in various embodiments thus provides a revolutionary approach to sample preparation and analyte extraction through its innovative combination of plasma-fluorinated porous frits and sorptive polymer coatings. The invention's unique integration of surface treatment and coating technology enables reproducible, conformal coating throughout the frit geometry while minimizing non-specific binding.

[0146] The device demonstrates exceptional performance across multiple applications, achieving lower limits of quantitation of 0.04 ng / ml for testosterone, 2.5 ng / ml for THC-COOH, and consistent detection of vitamin D metabolites down to 4.2 ng / ml. This high sensitivity is complemented by excellent reproducibility, with coefficient of variation typically around 5% across multiple batches.

[0147] The invention's key advantages include immunity to clogging from complex biological samples, elimination of emulsion formation, and prevention of analyte breakthrough due to its equilibrium-based extraction mechanism. The device requires no preconditioning or pre-wetting steps, enables effective matrix rinsing for clean extracts, and significantly reduces solvent usage compared to traditional methods.

[0148] The modular design allows integration into various analytical platforms, from simple pipette tips to complex automated systems. The three-step workflow - extraction, rinse, and elution - can be completed in under two minutes, representing a significant improvement over traditional 20-30 minute protocols.

[0149] The invention's plasma fluorination treatment serves the dual purpose of reducing nonspecific analyte binding while enhancing coating adhesion. This surface modification, combined with the sorptive polymer coating above its glass transition temperature, enables efficient extraction of small molecules while excluding larger interfering compounds.

[0150] The technology demonstrates broad applicability across different analyte types and matrices, successfully extracting compounds with LogP values ranging from 3.365 to 7.051. This versatility, combined with high reproducibility and simple automation potential, positions the invention as a significant advancement in sample preparation technology.

[0151] While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. It is not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the embodiments herein are not meant to be construed in a limiting sense. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is therefore contemplated that the invention shall also cover any such alternatives, modifications, variations or equivalents. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

Claims

CLAIMSI claim:

1. A device for extracting analytes from a fluid sample, comprising:a porous frit composed of sintered plastic polymer particles with a three-dimensional porous structure;a sorptive polymer coating applied to surfaces of said porous structure;wherein said porous frit has undergone plasma fluorination treatment prior to application of said sorptive polymer coating;wherein said sorptive polymer remains above its glass transition temperature at room temperature; andwherein said device is configured for insertion into a fluid flow path.

2. The device of claim 1, wherein said sintered plastic polymer particles are selected from the group consisting of polyethylene and polypropylene.

3. The device of claim 1, wherein said porous frit has a pore size range of 10 to 200 microns.

4. The device of claim 1, wherein said porous frit has an internal surface area of 0.1 to 1.0 square meters per gram.

5. The device of claim 1, wherein said sorptive polymer is selected from the group consisting of polydimethylsiloxane (PDMS), polybutadiene, siloxane copolymers, polydivinylbenzene (PDVB), polyurethane elastomers, polyacrylates, polymethacrylates, polyacrylonitrile-based copolymers, cyano-functionalized polymers, flexible phenol- functionalized copolymers, polymeric ionic liquids (PILs), polycaprolactone (PCL), fluorinated polymer copolymers, polyethylene-co-polypropylene copolymers, polystyrene-butadiene copolymers (SBS), ethylene-propylene-diene monomer (EPDM) rubbers, and any polymer that remains above its glass transition temperature at room temperature.

6. The device of claim 1, wherein said sorptive polymer coating has a thickness of 1 to 10 microns.

7. The device of claim 1, wherein said plasma fluorination treatment utilizes a fluorine- containing gas selected from the group consisting of tetrafluoromethane (CF4), sulfur hexafluoride (SFe), hexafluoroethane (C2F6), perfluoropropane (CsFs), hexafluoropropylene (CsFe), octafluorocyclobutane (C4Fs), and other fluorine-containing compounds capable of generating reactive fluorine species under plasma conditions and having sufficiently low boiling points to vaporize under low vacuum conditions, optionally in combination with oxygen or other reactive gases.

8. The device of claim 7, wherein said plasma fluorination treatment further includes oxygen or another reactive gas.

9. The device of claim 1, wherein said plasma fluorination treatment reduces non-specific analyte binding to the porous frit while enhancing adhesion of the sorptive polymer coating.

10. The device of claim 1, wherein said device is configured for insertion into a pipette tip.

11. The device of claim 1, wherein said device is configured for insertion into a fluid path selected from the group consisting of cartridge systems, spin columns, microfluidic devices, and flow-through configurations.

12. A method of manufacturing an analyte extraction device, comprising:providing a porous frit composed of sintered plastic polymer particles;subjecting said porous frit to plasma fluorination using a fluorine-containing gas; applying a sorptive polymer to the plasma-fluorinated porous frit using a solvent / anti- solvent system; andallowing evaporation of said solvent and anti-solvent to form a sorptive polymer coating on surfaces of said porous frit.

13. The method of claim 12, wherein said solvent / anti- solvent system comprises a solvent selected from hydrocarbons, ethers, esters, or alcohols, and an anti-solvent selected from water, alkanes, or short-chain alcohols.

14. The method of claim 12, further comprising conducting said plasma fluorination at a chamber pressure between 0.1-1.0 Torr and RF power settings of 50-500 watts for an exposure time of 30-300 seconds.

15. A method of extracting analytes from a fluid sample, comprising:providing a plasma-fluorinated porous frit with a sorptive polymer coating above its glass transition temperature;positioning said porous frit in a fluid flow path;flowing said fluid sample through said porous frit to allow analytes to partition into said sorptive polymer coating;flowing a rinse solution through said porous frit to remove unwanted matrix components; andflowing an elution solvent through said porous frit to desorb said analytes.

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