suppressor

Abstract

An electrolytic suppressor includes an eluent plate including an eluent channel through which an eluent including an ionic species flows; a first regenerant plate including a first regenerant channel and a second regenerant plate including a second regenerant channel; a first and second charged barriers disposed between the eluent plate and the first regenerant plate or the second regenerant plate, respectively; first and second metal plates, a plurality of screws or bolts fastening the first and second metal plates and compressing the eluent plate, the first and second regenerate plates, and the first and second charged barriers to form a leak resistant assembly with a pressure rating of at least 200 PSI; a stationary flow-through ion exchange material disposed within the eluent channel; a first screen and a first electrode disposed within the first regenerant channel; and a second screen and a second electrode disposed within the second regenerant channel.

Description

SUPPRESSORBACKGROUND

[0001] This application claims the benefit of the U.S. Provisional Application S / N 63 / 673,259, filed July 19, 2024, which is incorporated by reference in its entirety.

[0002] Ion chromatography is widely used in the analysis of samples containing anions or cations. A typical process begins with introducing a sample in the solution of a conductive eluent, and then sequentially goes through a chromatographic column, separating sample ions in the eluent, suppressing the eluent to remove the electrolyte counter ions from the sample ions, and detecting the sample ions. The purpose of suppression is to reduce the background conductivity of the eluent and increase the conductivity of the analytes, thus increasing the response in the subsequent detection.

[0003] Various suppressors are known and can be used for suppressing the eluent. Examples include those disclosed in U.S. Pat. Nos. 4,999,098; 6,077,434; 6,328,885; 7,618,826; 10,048,233; 10,175,211; and 10,571,439. In these suppressors, suppression is achieved by flowing the eluent through an eluent channel and a regenerant through a regenerant channel, where the eluent channel is separated from the regenerant channel by a charged membrane.

[0004] The natures of the membranes are critical as they keep all three channels separated from one another. Their roles are mainly two folds. First, the membranes prevent the bulk liquid from crossing the channels within the suppressor, they are therefore not permeable to the eluent and regenerant solutions that may be aqueous or contain organic solvents. Second, they allow only either anion or cation transport across the channels. By playing such a critical role, it is important for the membranes to be sturdy and to withstand enough backpressure without bursting. Bursting of the membrane leads to not only internal leakage within and between the channels but also potentially external leakages.

[0005] In light of the above, it is desirable to provide improved devices that overcome at least some of the above-mentioned challenges of existing devices.BRIEF SUMMARY

[0006] In a first aspect, an electrolytic suppressor for use in detecting analytes in a liquid sample includes: an eluent plate including an eluent channel through which an eluent including an ionic species flows, the eluent channel extending through the eluent plate; a first regenerant plate disposed on a first side of the eluent plate and including a first regenerant channel and a second regenerant plate disposed on a second side of the eluent plate and including a second regenerant channel; a first charged barrier having exchangeable ions capable of passing ions of only one charge, positive or negative, and of blocking bulk liquid flow, the first charged barrier disposed between the eluent plate and the first regenerant plate for separating the eluent channel from the first regenerant channel; a second charged barrier having exchangeable ions capable of passing ions of only one charge, positive or negative, and of blocking bulk liquid flow, the second charged barrier disposed between the eluent plate and the second regenerant plate for separating the eluent channel from the second regenerant channel; a first metal plate positioned opposite of the first regenerant plate from the eluent plate and a second metal plate positioned opposite of the second regenerative plate from the eluent plate, a plurality of screws or bolts fastening the first metal plate and the second metal plate and compressing the eluent plate, the first and second regenerate plates, and the first and second charged barriers to form a leak resistant assembly with a pressure rating of at least 200 PSI, wherein the pressure rating correspond to a pressure that the suppressor can operate at without leaking or damaging the suppressor; a stationary flow-through ion exchange material disposed within the eluent channel; a first screen and a first electrode disposed within the first regenerant channel; and a second screen and a second electrode disposed within the second regenerant channel.

[0007] In various embodiments of the first aspect, the eluent plate can include a frit for retention of the stationary flow-through ion exchange material in the eluent channel.

[0008] In various embodiments of the first aspect, the electrolytic suppressor can further include a first reinforced membrane, the first reinforced membrane disposed between the first charged barrier and the first regenerant plate, the first reinforced membrane serving as a gasket between the first charged barrier and the first regenerant plate to prevent the first regenerant plate from sheering the first charged barrier when assembled, and a second reinforced membrane, the second reinforced membrane disposed between the second charged barrier and the secondregenerant plate, the second reinforced membrane serving as a gasket between the second charged barrier and the second regenerant plate to prevent the first regenerant plate from sheering the first charged barrier when assembled.

[0009] In various embodiments of the first aspect, the pressure rating can be at least 500 PSI, such as 900 PSI. The pressure rating can be not greater than 2500 PSI.

[0010] In various embodiments of the first aspect, the first regenerant plate can include a first raised ridge sealing member and the second regenerant plate can include a second raised ridge sealing member.

[0011] In various embodiments of the first aspect, the first regenerant plate can include a first alignment ridge and the second regenerant plate can include a second alignment ridge.

[0012] In various embodiments of the first aspect, the eluent plate can include an alignment ridge.

[0013] In various embodiments of the first aspect, the electrolytic suppressor can further include a first plurality of alignment pegs in the first regenerant plate, extending through the first charge barrier, the eluent plate, and the second charged barrier and aligning with the second regenerant plate, and a second plurality of alignment pegs in the second regenerant plate, extending through the second charged barrier, the eluent plate, and the first charged barrier and aligning with the first regenerant plate.

[0014] In various embodiments of the first aspect, the volume of the stationary flow- through ion exchange material can be between 30% and 100% of the volume of the eluent channel defined by the eluent plate and the first and second charged barriers.

[0015] In various embodiments of the first aspect, the first and second metal plates can each have a thickness of at least 2.25 mm, such as at least 4 mm.

[0016] In various embodiments of the first aspect, the first and second metal plates and the screws or bolts provide a clamping force of at least 1500 lbs, such as at least 2000 lbs, even at least 2300 lbs. The clamping force can be not more than 3000 lbs.

[0017] In various embodiments of the first aspect, the first charged barrier can include one or more ion exchange membrane layers.

[0018] In various embodiments of the first aspect, the second charged barrier can include one or more ion exchange membrane layers.

[0019] In various embodiments, an ion chromatography system can include a pump; a chromatographic column for separation of analytes; the electrolytic suppressor of the first aspect; and a detector.

[0020] In a second aspect, a method of assembling an electrolytic suppressor includes providing a first subassembly including a first regenerant plate with a first regenerant channel, a first electrode and a first screen within a first regenerant channel of a first regenerant plate, the first charged barrier, and an eluent plate, the first subassembly including a first plurality of alignment pegs within the first regenerant plate and extending through the first charged barrier and the eluent plate; providing a second subassembly including a second regenerant plate with a second regenerant channel, a second electrode and a second screen within a second regenerant channel of a second regenerant plate, and a second charged barrier, the second subassembly including a second plurality of alignment pegs within the second regenerant plate and extending through the second charged barrier; adding a measured amount of stationary flow-through ion exchange material within an eluent channel of the eluent plate; joining the first subassembly and the second subassembly into an such that the first plurality of alignment pegs align with a first plurality of alignment holes in the second regenerant plate, the second plurality of alignment pegs alignment with a second plurality of alignment holes in the first regenerant plate, and the measured amount of stationary flow-through ion exchange material is retained within the eluent channel between the first charged barrier and the second charged barrier; and compressing the joined subassembly between first and second metal plates by tightening a plurality of screws or bolts.

[0021] These and other objects and advantages shall be made apparent from the accompanying drawings and the description thereof.BRIEF DESCRIPTION OF THE FIGURES

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments, and together with the general description given above, and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.

[0023] FIG. 1 illustrates a system for performing ion chromatography which uses an exemplary suppressor.

[0024] FIG. 2 illustrates an exploded perspective view of an exemplary suppressor.

[0025] FIGs 3, 4 A and 4B are closeup views illustrating exemplary sealing members, in accordance with various embodiments.

[0026] FIGs. 5, 6, 7, 8, and 9 are illustrations of various channel geometries, in accordance with various embodiments.

[0027] FIGs. 10A, 10B, and 10C are illustrations of alignment pegs, in accordance with various embodiments.

[0028] FIGs. 11 A and 1 IB are illustrations of a frit, in accordance with various embodiments.

[0029] FIGs. 12A, 12B, and 12C are illustrations of an alignment ridge, in accordance with various embodiments.

[0030] FIGs. 13 A and 13B are illustrations of an alignment ridge on an eluent plate, in accordance with various embodiments.DETAILED DESCRIPTION

[0031] FIG. 1 illustrates an embodiment of a chromatography system 100. Chromatography system 100 may include a pump 102, an electrolytic eluent generator 104, a continuously regenerated trap column 106, a degasser 108, a sample injector 110, a chromatographic separation column 112, an electrolytic suppressor 114, a detector 116, and a microprocessor 118. Chromatographic separation column 112 may be in the form of a capillarycolumn or an analytical column. A recycle line 120 may be used to transfer the liquid from an output of detector 116 to an inlet of the electrolytic suppressor 114, recycle line 122 may be used to transfer liquid from an outlet of electrolytic suppressor 114 to an inlet of degasser 108, and recycle line 124 may be used to transfer liquid from an outlet of degasser 108 to an inlet of continuously regenerated trap column 106.

[0032] Pump 102 can be configured to pump a liquid from a liquid source 124 and be fluidically connected to electrolytic eluent generator 104. In an embodiment, the liquid may be deionized water, an aqueous solution with electrolyte(s), or a mixture of an organic solvent with deionized water or with aqueous electrolyte(s) solution. A few example electrolytes are sodium acetate and acetic acid. The eluent mixture that contains an organic solvent may include a water miscible organic solvent such as, for example, methanol. Pump 102 can be configured to transport the liquid at a pressure ranging from about 20 PSI to about 15,000 PSI. Under certain circumstances, pressures greater than 15,000 PSI may also be implemented. It should be noted that the pressures denoted herein are listed relative to an ambient pressure (13.7 PSI to 15.2 PSI). Pump 102 may be in the form of a high-pressure liquid chromatography (HPLC) pump. In addition, pump 102 can also be configured so that the liquid only touches an inert portion of pump 102 so that a significant amount of impurities does not leach out. In this context, significant means an amount of impurities that would interfere with the intended measurement. For example, the inert portion can be made of polyetherether ketone (PEEK) or at least coated with a PEEK lining, which does not leach out a significant number of ions when exposed to a liquid.

[0033] An eluent is a liquid that contains an acid, base, salt, or mixture thereof and can be used to elute an analyte through a chromatography column. In addition, an eluent can include a mixture of a liquid and a water miscible organic solvent, where the liquid may include an acid, base, salt, or combination thereof. Electrolytic eluent generator 104 is configured to generate a generant. A generant refers to a particular species of acid, base, or salt that can be added to the eluent. In an embodiment, the generant may be a base such as cation hydroxide or the generant may be an acid such as carbonic acid, phosphoric acid, acetic acid, methanesulfonic acid, or a combination thereof.

[0034] Referring to FIG. 1, eluent generator 104 can be configured to receive the liquid from pump 102 and then add a generant to the liquid. The liquid containing the generant can be outputted from eluent generator 104 to an inlet of continuously regenerated trap column 106.

[0035] Continuously regenerated trap column 106 is configured to remove cationic or anionic contaminants from the eluent. Continuously regenerated trap column 106 can include an ion exchange bed with an electrode at the eluent outlet. An ion exchange membrane interface can separate the eluent from a second electrode and contaminate ions can be swept through the ion exchange membrane towards the second electrode. In various embodiments, anion removal can utilize an anion exchange bed with a cathode at the eluent outlet separated from an anode by an anion exchange membrane. Alternatively, cation removal can utilize a cation exchange bed with an anode at the eluent outlet separated from a cathode by a cation exchange membrane. The contaminate ions can be swept out of regenerated trap column 106 using a recycled liquid via a recycle line 124 that is downstream of degas assembly 108.

[0036] Degasser 108 may be used to remove residual gases in eluents. In an embodiment, a residual gas may be hydrogen and oxygen. Degasser 108 may include a tubing section that is gas permeable and liquid impermeable such as, for example, amorphous fluoropolymers or more specifically Teflon AF. The flowing liquid can be outputted from degasser 108 to sample injector 110 with a substantial portion of the gas removed. The gas can be swept out of degasser 108 using a recycled liquid via a recycle line 122 that is downstream of electrolytic suppressor 114. The recycled liquid containing the residual gas can also be outputted from degasser 108 and directed to the continuously regenerated trap column 106.

[0037] Sample Injector 110 can be used to inject a bolus of a liquid sample into an eluent stream. The liquid sample may include a plurality of chemical constituents (i.e., matrix components) and one or more analytes of interest.

[0038] Chromatographic separation column 112 can be used to separate various matrix components present in the liquid sample from the analyte(s) of interest. Typically, chromatographic separation column 112 may be in the form of a hollow cylinder that contains a packed stationary phase. As the liquid sample flows through chromatographic separation column 112, the matrix components and target analytes can have a range of retention times foreluting off of chromatographic separation column 112. Depending on the characteristics of the target analytes and matrix components, they can have different affinities to the stationary phase in chromatographic separation column 112. An output of chromatographic separation column 112 can be fluidically connected to the electrolytic suppressor 114.

[0039] Electrolytic suppressor 114 can be used to reduce eluent conductivity background and enhance analyte response through efficient exchange of eluent counterions for regenerant ions. Electrolytic suppressor 114 can include an anode chamber, a cathode chamber, and an eluent suppression bed chamber separated by ion exchange membranes. The anode chamber and / or cathode chamber can produce regenerate ions. The eluent suppression bed chamber can include a flow path for the eluent separated from the regenerant by an ion exchange barrier and eluent counterions can be exchanged with regenerate ions across the ion exchange barrier. The cathode chamber or anode chamber can be supplied a recycled liquid via a recycle line 120 that is downstream of conductivity detector 116. An output of electrolytic suppressor 114 can be fluidically connected to detector 116 to measure the presence of the separated chemical constituents of the liquid sample.

[0040] As illustrated in FIG. 1, the fluidic output of the eluent from detector 116 is recycled to electrolytic suppressor 114 via recycle line 120, the fluidic output of the electrolytic suppressor 114 is recycled to degasser 108 via recycle line 122, the fluidic output from degasser 108 is recycled to continuously regenerated trap column 106 via recycle line 124, and the fluidic output of the continuously regenerated trap column 106 flows to waste.

[0041] Detector 116 may be in the form of ultraviolet- visible spectrometer, a fluorescence spectrometer, an electrochemical detector, a conductometric detector, a charge detector, or a combination thereof. Details regarding the charge detector that is based on a charged barrier and two electrodes can be found in US Pre-Grant Publication No. 20090218238, which is hereby fully incorporated by reference herein. For the situation where recycle line 120 is not needed, detector 116 may also be in the form of a mass spectrometer or a charged aerosol detector. The charged aerosol detector nebulizes the effluent flow and creates charged particles that can be measured as a current proportional to the analyte concentration. Details regarding the charged aerosol detector can be found in US Patent No.’s 6,544,484; and 6,568,245, which are hereby fully incorporated by reference herein.

[0042] An electronic circuit may include microprocessor 118, a timer, and a memory portion. In addition, the electronic circuit may include a power supply that are configured to apply a controlling signal, respectively. Microprocessor 118 can be used to control the operation of chromatography system 100. Microprocessor 118 may either be integrated into chromatography system 100 or be part of a personal computer that communicates with chromatography system 100. Microprocessor 118 may be configured to communicate with and control one or more components of chromatography system such as pump 102, eluent generator 104, sample injector 110, and detector 116. The memory portion may be used to store instructions to set the magnitude and timing of the current waveform with respect to the switching of sample injector 110 that injects the sample.

[0043] FIG. 2 is an exploded view of exemplary suppressor 200 including an eluent plate 202, charged barriers 204, reinforced membranes 206, screens 208, electrodes 210A and 210B, regenerant plates 212, and metal plates 214.

[0044] The eluent plate 202 includes an eluent channel 216 extending through the eluent plate 202. The eluent channel 216 is further bounded by the charged barriers 204. In various embodiments, the charged barriers 204 can each include one or more ion exchange membrane layers. The eluent member 202 can have an inlet port 220 and an outlet port 222. The eluent member 202 is configured for the eluent to flow from the inlet port 220, through the primary channel 216, and then to the outlet port 222.

[0045] The regenerant plates 212 each include a first surface 224 that faces the eluent channel 216. The first surface at least partially defines a regenerant channel 218. The regenerant channel 218 includes a regenerant inlet port 226 and a regenerant outlet port 228 and is configured for the regenerant to from the regenerant inlet port 226 to the regenerant outlet port 228. As shown, this results in the regenerant flow being the opposite direction of the eluent flow. In alternate embodiments, the regenerant flow can be arranged to flow in the same direction as the eluent flow.

[0046] Screens 208 can include a polyolefin substrate in the form of a mesh or grid having a functional polymer layer disposed thereon. In various embodiments, the functional polymer layer can have a thickness ranging from about 1 micron to about 20 microns, and a layerpore structure having a pore size ranging from about 1 nm to about 100 nm. The functional polymer layer can include an ion exchange layer. Alternatively, a ion exchange particle-based resin can be used in place of screens 208.

[0047] A stationary flow-through ion exchange material 230 is disposed in the eluent channel 216. The stationary flow-through ion exchange material 230 can be a particle-based resin. In various embodiments, the flow-through ion exchange material 230 can be retained within the eluent channel 216 with frits, such as the frits described in more detail in Figs 11A and 1 IB. The stationary flow-through ion exchange material 230 can include a polyolefin substrate having a functional polymer layer disposed thereon. The polyolefin substrate can have a pore structure with a pore size ranging from about 5 microns to about 250 microns. The functional polymer layer can have a thickness ranging from about 0.001 micron to about 20 microns, and a layer pore structure having a pore size ranging from about 1 nm to about 1000 nm. The functional polymer layer can include an ion exchange layer. In alternate embodiments, the stationary flow-through ion exchange material 230 can be a screen similar to screens 208 or can be a porous monolithic structure. In various embodiments, the volume of the stationary flow-through ion exchange material 230 can be between 30% and 100% of the volume of the eluent channel 216 defined by the eluent plate 202 and the charged barriers 204.

[0048] The charged barriers 204 and the reinforced membranes 206 are disposed between the eluent plate and the regenerant plate. As illustrated, the reinforced membranes 206 are positioned closer to the regenerant plate 212 with the charged barriers 204 positioned closer to the eluent plate 202. In alternate embodiments, the charged barriers 204 can be closer to the regenerant plate 212 and the reinforced charged barriers 204 can be closer to the eluent plate 202. The charged barriers 204 and reinforced membranes 206 are configured to pass ions of only one charge, positive or negative, and to block bulk liquid flow. The charged barriers 204 and the reinforced membranes 206 have the same charge polarity. This allows ions to move between the eluent channel 216 and the regenerant channels 218 but prevents the exchange of the bulk liquid between the eluent channel 216 and the regenerant channels 218.

[0049] The electrode 210A can be an anode and electrode 210B can be a cathode. Electrodes 210A and a210B can be disposed in the regenerant channels 218. A current can be applied to the electrodes 210A and 210B such that negative ions are driven towards the anodeand positive ions are driven towards the cathode. Depending on the analyte of interest, the charged barriers 204 and reinforced membranes 206 can allow either the positive ions to pass or the negative ions to pass. In the case that the charged barriers 204 and reinforced membranes 206 allow negative ions to pass, negative ions in the eluent channel migrate to the regenerant channel with the anode while hydroxide ions produced at the cathode migrate into the eluent channel, while positively charged analyte ions remain in the eluent channel. Alternatively, when the charged barriers 204 and reinforced membranes 206 allow positive ions to pass, positive ions in the eluent channel migrate to the regenerant channel with the cathode while hydrogen ions and hydronium ions produced at the anode migrate into the eluent channel, while negatively charged analyte ions remain in the eluent channel.

[0050] In various embodiments, the electrode can be a mesh. In various embodiments, the electrode mesh can include titanium, platinum, or other metals. Generally, it is beneficial for the electrode mesh to have good electrical and corrosion resistance properties. In particular embodiments, the electrode mesh can include a titanium mesh coated with platinum.

[0051] The suppressor 200 is in a symmetric arrangement with regenerant channels 218 on both sides of the eluent plate 202. In alternate embodiments, the suppressor can have only one regenerant channel containing one electrode and positioned on one side of the eluent plate, and the other electrode is positioned in the eluent channel .

[0052] In various embodiments, the regenerant channels can be arranged such that the regenerant flow through the two regenerant channels 218 is in parallel or in series. For example, in parallel arrangement, a regenerant flow can be split upstream of the regenerant channels 218 such that a first portion of the regenerant flow proceeds through a first regenerant channel 218 while a second portion of the regenerant flow proceeds through the second regenerant channel 218. The regenerant flow can be recombined after exiting the regenerant channels 218. In a series arrangement, the regenerant flow can flow through a first regenerant channel 218 and then flow through the second regenerant channel 218.

[0053] It is necessary to form a good seal to prevent leakage between the regenerant plate and the reinforced membrane and between the eluent plate and the charged barrier. The seal can be a face seal formed by sandwiching the reinforced membrane and the charged barrier betweenthe regenerant plate and the eluent plate. In various embodiments, a sealing member can be incorporate to focus the pressure at the perimeter of the regenerant channel and the eluent channel. In various embodiments, the sealing member can be raised ridge formed in the regenerant plate (see FIG. 3), the eluent plate, or both. Alternatively, the sealing member can be a separate piece, such as an O-ring or an insert (see FIG 4A and 4B). Applicant observed that the charged barrier can be sheered by a raised ridge sealing member when applying high compression to the suppressor and that the use of a reinforced membrane acts as a gasket and prevents the raised ridge from sheering the charged barrier.

[0054] In various embodiments, screws or bolts can be used to secure the assembly, as shown in more detail in FIG. 10B. The screws or bolts can apply a force to the metal plates 214 to compress the assembly. In various embodiments, the metal plates 214 can have a thickness of at least 2.25 mm, such as at least 4 mm. With the screws or bolts in place, the metal plates can apply a clamping force of at least 1500 lbs, such as at least 2000 lbs, even 2300 lbs. In some embodiments, the clamping force may not exceed 3000 lbs.

[0055] In various embodiments, the suppressor 200 can have a pressure rating of at least 200 PSI, such as 500 PSI, even 900 PSI. Generally, the pressure rating may not exceed 2500 PSI, although higher pressure ratings are possible. The pressure rating can be a pressure that the suppressor can operate without leaking. Leaks can be external leaks resulting in liquid exiting the suppressor 200, such as from the sides. Additionally, leaks can be internal leaks resulting in fluid transfer between the eluent channel 216 and the regenerant channel 218 but still contained within the suppressor 200. Leaks can be caused, for example, by rupturing the charged barrier or by forcing liquid passed the seal. The pressure rating can be determined by operating the suppressor for a period of time, such as at least 10 minutes, at least 30 minutes, even at least 60 minutes, and then determining if leaks have occurred. In some embodiments, visible leaks may be observed. In other embodiments, a pressure drop test can be performed. The pressure drop test can pressurize the suppressor 200 and monitor the pressure over a period of time. For example, after operating the suppressor 200 for a period of time, fluid flow through the suppressor 200 can be stopped and the pressure over time can be observed. Decreasing pressure over time can indicate a leak whereas the pressure holding steady can indicate no leaks. Thepressure rating of the suppressor 200 can be a pressure at which the suppressor can be operated without failing the leak test.

[0056] FIG. 3 is a close-up view of a regenerant plate 300 showing a raised ridge 302 integral to the regenerant plate 300. The raised ridge 302 surrounds the region of the regenerant channel 304. In various embodiments, the integral raised ridge 302 can be formed during machining or injection molding of the regenerant plate 300.

[0057] FIG. 4A and 4B show close-up views of a regenerant plate 400 having an insert 402 positioned within a groove 404 surrounding the regenerant channel 406. Generally, the insert 402 is molded or machined separately and can be inserted into the groove 404 machined or molded in the regenerant plate 400. In some embodiments, the insert 402 can be fixed in place such as by press fitting, gluing, or laser welding the insert 402 into the groove 404. In some embodiments, the regenerant plate 400 can be molded around the insert, such as by placing the machined or molded insert 402 into the mold for the regenerant plate 400. In particular instances, insert 402 and the regenerant plate 400 can be formed by two-shot injection molding where the insert 402 is injection molded in place and then the regenerant plate 400 is injection molded over the insert 402.

[0058] Various shapes can be utilized for the eluent channel and regenerant channel. Typically, the regenerant channel shape should be similar to the eluent channel shape and aligned with the eluent channel. Various parameters can be considered when selecting a channel shape. In general, increasing the channel cross section of the eluent channel for a given flow rate can increase peak broadening. Conversely, increasing the membrane contact surface area can improve suppressor performance. Thus, it can be generally advantageous to increase the width of the channel to maximize membrane contact surface area while decreasing the depth of the channel to minimize channel cross section. Additionally, dwell time within the suppressor can affect the performance of the suppressor, with a longer dwell time resulting in better suppression. The dwell time is a measure of how long it takes for eluent to pass through the eluent channel and can be a function of channel cross section and channel length, as well as flow rate. Significantly, all of the channel designs presented are co-planer so that regenerant channels can be positioned on either side of the eluent channel to maximize current efficiency for suppression.

[0059] FIG 5 illustrates a straight run channel design 500. The eluent enters the channel 502 at an entrance end 504, spreads out to the width of the channel body 506, and continues to an exit end 508.

[0060] FIG 6 illustrates a serpentine channel design 600. The eluent enters the channel 602 at an entrance end 604. Rather than spreading out like in the straight run channel design 500, the eluent follows a serpentine path 606 to the exit end 604. The serpentine path 606 increases the length of the channel while maintaining a consistent channel width.

[0061] FIG 7 illustrates a U-shaped path design 700. The eluent enters the channel 702 at an entrance end 704, flows down a first leg 706, turns around at a curve 708, then flows down the second leg 710 to an exit end 712. The channel 702 narrows at the curve 708 narrows providing a flow restriction to reduce channeling. Another feature of the U-shaped path design 700 is that the entrance end 704 of the channel 702 and the exit end 712 of the channel 702 are on the same side of the suppressor.

[0062] Channeling of the eluent can occur when a portion of the flow through the channel is faster than the remainder of the flow. This can occur when there are inconsistencies in the stationary flow-through ion exchange material allowing a freer path in one portion of the channel than in another. This may typically occur at the edges of the channel. Channel reduces the resolution of the chromatography by mixing some earlier eluent (moving along a slower path) with some later eluent (moving along a faster path) and can result in peak broadening and reduced separation. The flow restriction in the middle of the path can cause the eluent to remix, thereby reducing the effect of the channeling.

[0063] FIG 8 illustrates a flow restricted path design 800. The eluent enters the channel 802 at an entrance end 804 and expands into a first region 806. The eluent then passes through a flow restriction 808 before expanding into a second region 810 and then to the exit end 812.

[0064] FIG 9 illustrates a restricted flow path design 900 with multiple flow restrictions. The eluent enters the channel 902 at an entrance end 904 and expands into a first region 906. The eluent then passes through a first flow restriction 908 before expanding into a second region 910. The eluent then passes through a second flow restriction 912 before expanding into a third region 914 and then to the exit end 916.

[0065] FIGs. 10A, 10B, and IOC show are illustrations of alignment pegs. The first regenerant plate 212A includes a first plurality of alignment pegs 1002 and the second regenerant plate 212B includes a second plurality of alignment pegs 1004. Additionally, second regenerant plate 212B includes a first plurality of alignment holes 1006 and first regenerate plate 212A includes a second plurality of alignment holes 1008. During assembly, the alignment pegs 1002 and 1004 can be used to align the charged barriers 204, the reinforced membranes 206, and the eluent plate 202. Specifically, a first subassembly 1010 can include the first regenerant plate 212A, the reinforced membrane 206, the charged barrier 204, and the eluent plate 202. The second subassembly 1012 can include the second regenerant plate 212A, the reinforced membrane 206, and the charged barrier 204. As seen in FIG. 10C, the alignment pegs can include a flared portion to aid in the retention of the components of the subassembly, as well as ensuring the components of the subassembly remain aligned. Additionally, when the two subassemblies are brought together, the first plurality of alignment pegs 1002 can align with the first plurality of alignment holes 1006 and the second plurality of alignment pegs 1004 can align with the second plurality of alignment holes 1008 to ensure the alignment of each component of the assembly, including the regenerant plates 212, the charged barriers 204, the reinforced membranes 206 and the eluent plate 202.

[0066] FIGs. 11 A and 1 IB are illustrations of a portion of the eluent plate in proximity to the outlet port 222. The eluent channel 216 can include a notch 1102 for retaining a frit 1104. In various embodiments, the frit 1104 can be press fit into the notch 1102. In various embodiments, the frit 1104 can be a porous disk, such as a polyethylene disk, with a porosity that allows passage of eluent, but retains the stationary flow-through ion exchange material 230. The eluent plate 202 also include an outlet passageway 1106 running from the frit 1104 to the outlet port 222. In various embodiments, a connector (not shown) can form a face seal with the outlet passageway 1106 within the outlet port 222. In various embodiments, similar features can be included on the inlet side of the eluent plate 202.

[0067] FIGs. 12A and 12B are embodiment of a regenerant plate 212 with an alignment ridge 1202. The alignment ridge 1202 is separate from the raised ridge sealing member 302 and may not be involved with forming a seal. As seen in FIG. 12C, there can be a gap between the corresponding alignment ridges 1202 on the two regenerant plates 212 when assembled (seedetail 1204 of FIG. 12C). Additionally, the screws or bolts 1206 are illustrated extending through the full assembly.

[0068] FIGs. 13A and 13B are illustrations of an alignment ridge 1302 on an eluent plate 202. Detail 1304 of FIG. 13B shows a gap between the alignment ridge 1302 on the eluent plate 202 and the regenerant plates 212 such that the alignment ridge is not involved with forming a seal.

[0069] In the present disclosure the singular forms "a", "an" and "the" include the plural reference, and reference to a particular numerical value includes at least that particular value, unless the context clearly indicates otherwise. Thus, for example, a reference to "a material" is a reference to at least one of such materials and equivalents thereof known to those skilled in the art, and so forth.

[0070] The modifier "about" should be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression "from about 2 to about 4" also discloses the range "from 2 to 4." When used to modify a single number, the term "about" may refer to plus or minus 10% of the indicated number and includes the indicated number. For example, "about 10%" may indicate a range of 9% to 11%, and "about 1 " means from 0.9 to 1.1.

[0071] When a list is presented, unless stated otherwise, it is to be understood that each individual element of that list and every combination of that list is to be interpreted as a separate embodiment. For example, a list of embodiments presented as "A, B, or C" is to be interpreted as including the embodiments, "A," "B," "C," "A or B," "A or C," "B or C," or "A, B, or C."

[0072] It is to be appreciated that certain features of the invention which are, for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. That is, unless obviously incompatible or excluded, each individual embodiment is deemed to be combinable with any other embodiment s) and such a combination is considered to be another embodiment. Conversely, various features of the invention that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any sub-combination. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as "solely," "only" and the like in connection with the recitation of claim elements,or use of a "negative" limitation. Finally, while an embodiment may be described as part of a series of steps or part of a more general structure, each said step may also be considered an independent embodiment in itself.

[0073] While the present disclosure has illustrated by description several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications may readily appear to those skilled in the art. Furthermore, features from separate lists can be combined; and features from the examples can be generalized to the whole disclosure.

Claims

WHAT IS CLAIMED IS:

1. An electrolytic suppressor for use in detecting analytes in a liquid sample, the apparatus comprising: an eluent plate including an eluent channel through which an eluent including an ionic species flows, the eluent channel extending through the eluent plate; a first regenerant plate disposed on a first side of the eluent plate and including a first regenerant channel and a second regenerant plate disposed on a second side of the eluent plate and including a second regenerant channel; a first charged barrier having exchangeable ions capable of passing ions of only one charge, positive or negative, and of blocking bulk liquid flow, the first charged barrier disposed between the eluent plate and the first regenerant plate for separating the eluent channel from the first regenerant channel; a second charged barrier having exchangeable ions capable of passing ions of only one charge, positive or negative, and of blocking bulk liquid flow, the second charged barrier disposed between the eluent plate and the second regenerant plate for separating the eluent channel from the second regenerant channel; a first metal plate positioned opposite of the first regenerant plate from the eluent plate and a second metal plate positioned opposite of the second regenerative plate from the eluent plate, a plurality of screws or bolts fastening the first metal plate and the second metal plate and compressing the eluent plate, the first and second regenerate plates, and the first and second charged barriers to form a leak resistant assembly with a pressure rating of at least 200 PSI, wherein the pressure rating correspond to a pressure that the suppressor can operate at without leaking or damaging the suppressor; a stationary flow-through ion exchange material disposed within the eluent channel; a first screen and a first electrode disposed within the first regenerant channel; and a second screen and a second electrode disposed within the second regenerant channel.

2. The electrolytic suppressor of claim 1, wherein the eluent plate includes a frit for retention of the stationary flow-through ion exchange material in the eluent channel.

3. The electrolytic suppressor of claim 1, further comprising a first reinforced membrane, the first reinforced membrane disposed between the first charged barrier and the first regenerant plate, the first reinforced membrane serving as a gasket between the first charged barrier and the first regenerant plate to prevent the first regenerant plate from sheering the first charged barrier when assembled, and a second reinforced membrane, the second reinforced membrane disposed between the second charged barrier and the second regenerant plate, the second reinforced membrane serving as a gasket between the second charged barrier and the second regenerant plate to prevent the first regenerant plate from sheering the first charged barrier when assembled.

4. The electrolytic suppressor of claim 1, wherein the pressure rating is at least 500 PSI.

5. The electrolytic suppressor of claim 4, wherein the pressure rating is at least 900 PSI.

6. The electrolytic suppressor of claim 1, wherein the pressure rating is not greater than 2500 PSI.

7. The electrolytic suppressor of claim 1, wherein the first regenerant plate includes a first raised ridge sealing member and the second regenerant plate includes a second raised ridge sealing member.

8. The electrolytic suppressor of claim 1, wherein the first regenerant plate includes a first alignment ridge and the second regenerant plate includes a second alignment ridge.

9. The electrolytic suppressor of claim 1, wherein the eluent plate includes an alignment ridge.

10. The electrolytic suppressor of claim 1, further comprising a first plurality of alignment pegs in the first regenerant plate, extending through the first charge barrier, the eluent plate, and the second charged barrier and aligning with the second regenerant plate,and a second plurality of alignment pegs in the second regenerant plate, extending through the second charged barrier, the eluent plate, and the first charged barrier and aligning with the first regenerant plate.

11. The electrolytic suppressor of claim 1, wherein the volume of the stationary flow- through ion exchange material is between 30% and 100% of the volume of the eluent channel defined by the eluent plate and the first and second charged barriers.

12. The electrolytic suppressor of claim 1, wherein the first and second metal plates each have a thickness of at least 2.25 mm.

13. The electrolytic suppressor of claim 12, wherein the first and second metal plates each have a thickness of at least 4 mm.

14. The electrolytic suppressor of claim 1, wherein the first and second metal plates and the screws or bolts provide a clamping force of at least 1500 lbs.

15. The electrolytic suppressor of claim 14, wherein the clamping force is at least 2000 lbs.

16. The electrolytic suppressor of claim 15, wherein the clamping force is at least 2300 lbs.

17. The electrolytic suppressor of claim 14, wherein the clamping force is not more than 3000 lbs.

18. The electrolytic suppressor of claim 1, wherein the first charged barrier includes one or more ion exchange membrane layers.

19. The electrolytic suppressor of claim 1, wherein the second charged barrier includes one or more ion exchange membrane layers.

20. An ion chromatography system comprising: a pump; a chromatographic column for separation of analytes;the electrolytic suppressor of claim 1; and a detector.

21. A method of assembling an electrolytic suppressor comprising, providing a first subassembly including a first regenerant plate with a first regenerant channel, a first electrode and a first screen within a first regenerant channel of a first regenerant plate, the first charged barrier, and an eluent plate, the first subassembly including a first plurality of alignment pegs within the first regenerant plate and extending through the first charged barrier and the eluent plate; providing a second subassembly including a second regenerant plate with a second regenerant channel, a second electrode and a second screen within a second regenerant channel of a second regenerant plate, and a second charged barrier, the second subassembly including a second plurality of alignment pegs within the second regenerant plate and extending through the second charged barrier; adding a measured amount of stationary flow-through ion exchange material within an eluent channel of the eluent plate; joining the first subassembly and the second subassembly into an such that the first plurality of alignment pegs align with a first plurality of alignment holes in the second regenerant plate, the second plurality of alignment pegs alignment with a second plurality of alignment holes in the first regenerant plate, and the measured amount of stationary flow-through ion exchange material is retained within the eluent channel between the first charged barrier and the second charged barrier; and compressing the joined subassembly between first and second metal plates by tightening a plurality of screws or bolts.

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