Digitally controlled peristaltic pump for ion chromatography

Abstract

The systems and methods taught herein include a peristaltic pump positioned along the regenerator flow path to supply a regenerator fluid to an ion exchange device (such as a chemical suppressor) and other devices in a chromatography system. The peristaltic pump provides a stable and highly controllable flow rate that improves run-to-run repeatability within the system and does not require the regenerator supply to be under pressure. Several systems and methods taught herein utilize the peristaltic pump to enable the stable delivery of other fluids, such as water, to associated systems, such as ion exchange devices operating in electrolytic mode.

Description

Technical Field

[0001] (Cross - reference to related applications) This application claims the priority of U.S. Provisional Patent Application No. 63 / 468,144, filed on May 22, 2023, the entire content of which is incorporated herein by reference.

Background Art

[0002] In ion chromatography (IC) applications, the role of the ion - exchange device is to enhance the conductivity signal. Generally, the suppression reaction utilizes a regenerant source of ions supplied externally or via a recycle mode, exchanges with the eluent and sample counter - ions through an ion - exchange transport mechanism, resulting in a suppressed eluent background with an improved analyte response. Suppression can be achieved mainly through two paths: a chemically regenerated ion - exchange device and an electrolytically regenerated ion - exchange device. The regenerant source for chemical suppression can use an external regenerant delivery path, while an electrolytic ion - exchange device can operate with either an external or a recirculated regenerant delivery path.

Summary of the Invention

[0003] Disclosed herein is an ion chromatography system including a chromatographic separation device for separating analytes in a sample fluid. The ion chromatography system also includes an ion - exchange device for receiving the sample fluid from the chromatographic separation device. The ion chromatography system also includes a peristaltic pump for supplying a regenerant fluid to the ion - exchange device.

[0004] This specification provides a method for performing ion chromatography. The method includes separating analytes in a fluid sample using a chromatographic separation device. The method also includes suppressing the conductivity of non-analyte electrolytes in the separated fluid sample using an ion exchange device. The method also includes supplying a regenerating fluid to the ion exchange device using a peristaltic pump. The method also includes detecting the analytes in the separated fluid sample using a detector. [Brief explanation of the drawing]

[0005] To facilitate the identification of any particular element or action, the most significant digit(s) in the reference number refers to the figure number in which that element was first introduced. [Figure 1] This specification illustrates chromatographic systems for ion separation, including a regenerating peristaltic pump, according to various embodiments taught herein. [Figure 2] Perspective views of peristaltic pumps in an open state, according to various embodiments taught herein, are illustrated. [Figure 3] Let's illustrate this with an example of a peristaltic pump in a closed state. [Figure 4] Let's illustrate this with an exploded view of a peristaltic pump. [Figure 5] Let's illustrate the reverse angle diagram of a peristaltic pump with an example. [Figure 6] This example illustrates a cabinet-type chromatography system having a peristaltic pump mounted on the front panel of the chromatography system. [Figure 7] This specification illustrates graphical user interfaces (GUIs) for chromatography systems according to various embodiments taught herein. [Figure 8] This specification includes plots showing the results of reproducibility experiments performed using a chromatography system according to the embodiments described herein. [Figure 9A]This specification illustrates exemplary chromatography systems, including a carbonate removal device connected via a first regenerator flow path configuration, according to various embodiments taught herein. [Figure 9B] This specification illustrates a chromatography system comprising a carbonate removal device 902 having a second regenerator flow path configuration, according to several embodiments taught herein. [Figure 10] This specification illustrates a chromatography system including post-column reagent delivery, as taught in several embodiments. [Modes for carrying out the invention]

[0006] The section headings used in this specification are for structural purposes only and should not be construed as limiting the subject matter described in any way.

[0007] In this detailed description of various embodiments, many specific details are included for illustrative purposes to provide an overall understanding of the disclosed embodiments. However, those skilled in the art will understand that these various embodiments can be carried out with or without these specific details. In other instances, structures and devices are shown in the form of block diagrams. Furthermore, those skilled in the art will readily understand that the specific order in which the methods are presented and performed is illustrative, and the order can be changed and is intended to remain within the spirit and scope of the various embodiments disclosed herein.

[0008] All documents and similar materials cited in this application, including but not limited to patents, patent applications, articles, books, papers, and internet web pages, are expressly incorporated by reference in their entirety for any purpose. Unless otherwise stated, all technical and scientific terms used herein are to be understood in common by those skilled in the art in which the various embodiments described herein belong.

[0009] It will be understood that there is an implicit "approximation" before the temperature, concentration, time, pressure, flow rate, cross-sectional area, etc., considered in this instruction, so that only very small deviations fall within the scope of this instruction. In this application, the use of the singular form includes the plural form unless otherwise specifically stated. Similarly, the use of "comprise," "comprises," "comprising," "contain," "contains," "containing," "include," "includes," and "including" is not intended to be limiting. It should be understood that the above general explanation and the following detailed explanation are illustrative and descriptive only and do not limit this instruction.

[0010] As used herein, “a” or “an” may also mean “at least one” or “one or more.” Furthermore, the use of “or” is inclusive, and the phrase “A or B” applies when “A” is applicable, when “B” is applicable, or when both “A” and “B” are applicable. In addition, unless otherwise required by context, singular terms shall include plurals, and plural terms shall include singulars.

[0011] A “system” refers to a set of components, whether actual or abstract, in which each component interacts with at least one other component within the whole, or constitutes a whole in which it is associated.

[0012] When used herein, the eluent is a liquid containing an acid, base, salt, or a mixture thereof, which can be used to elute an analyte through a chromatography column. In addition, the eluent may include a mixture of a liquid and a water-miscible organic solvent, and the liquid may contain an acid, base, salt, or a combination thereof.

[0013] In some embodiments taught herein, an electrolytic eluent generator can be provided for producing a generalant. As used herein, “generant” refers to a specific type of acid, base, or salt that can be added to the eluent. In some embodiments, the generalant may be a base such as a cationic hydroxide, or the generalant may be an acid such as carbonic acid, phosphoric acid, acetic acid, methanesulfonic acid, or a combination thereof.

[0014] The systems and methods taught herein include a peristaltic pump positioned along the regenerator flow path to supply a regenerator fluid to an ion exchange device and other devices within the chromatography system. The peristaltic pump provides a stable and highly controllable flow rate that improves run-to-run reproducibility within the system and does not require the regenerator supply to be under pressure. In displacement chemical regeneration (DCR), the concentration of the regenerator solution is periodically adjusted through dilution. The need for this periodic adjustment provides a potential source of error if the regenerator solution is not at the expected or anticipated concentration during the run of the experiment. Conventionally, the regenerator solution is supplied to the system from a bottle placed under pressure using a pressurized gas source. The gas source pushes the regenerator solution out of the bottle at the appropriate rate and concentration. However, using a pressurized feed, the regenerator delivery flow rate can be susceptible to downstream pressure changes and may depend on the level of regenerator remaining in the container, both of which can cause flow rate fluctuations or spikes and affect chromatography performance. The use of a peristaltic pump to supply the regenerator fluid as taught herein overcomes these problems because the flow rate is very stable and less susceptible to pressure changes in the flow path or the level of regenerator remaining in the supply container. Therefore, the chromatographic performance resulting from the system of this disclosure is highly reproducible.

[0015] In addition, the systems and methods taught herein can improve safety by eliminating the need for pressurizing the regenerator fluid container. DCR supports low to medium concentration eluents (cationic and anionic) and is most recommended for carbonate chemical applications. Since most eluents and regenerators are caustic or corrosive, conventional systems using pressurized bottles present a safety hazard, as operators may be potentially harmed by forced discharge of the fluid or explosion of the container, especially during repeated mixing and filling of these pressurized vessels, which are part of the DCR process. The systems and methods taught herein can improve safety by using a peristaltic pump to provide a stable supply of regenerator from an unpressurized regenerator supply unit, such as a vessel or container.

[0016] Several systems and methods taught herein utilize peristaltic pumps to enable the stable delivery of other fluids, such as water, to associated systems, such as ion exchange devices operating in electrolytic mode. In certain applications, the systems and methods taught herein can utilize peristaltic pumps to supply recycled regenerators to ion exchange devices. In addition, the systems and methods taught herein utilize peristaltic pumps to steadily deliver gases or fluids to carbonate removal devices that physically or chemically remove dissolved carbon dioxide gas from a fluid (such as an eluent) along a flow path.

[0017] Various methods are used to supply the regenerator fluid in a regular and stable flow, typically provided through an additional dedicated peristaltic pump. While many regenerator pumps are external to the IC instrument, this disclosure provides internal or externally mounted peristaltic pump solutions, including peristaltic pumps that enable more immediate and synchronous delivery approaches for chemical or electrolytic suppression. The technical field of regenerator peristaltic pumps is their use in analytical IC instruments during sample preparation, after sample handling, or during the operational process of analysis using the application. Some examples of devices taught herein can be used in any liquid chromatography application where it is desired to provide a stable liquid flow at low pressure.

[0018] Figure 1 illustrates a chromatography system 102 for ion separation, including a regenerant peristaltic pump 134, according to various embodiments taught herein. The chromatography system 102 includes an injection valve 110 that receives an eluent or sample fluid from a high-pressure input 126, a guard column 104, a chromatography separation device 106, an ion exchange device 130, a detector 138, a flow unit 108, a backpressure coil 112, and a waste output 132 along a sample flow path 122. The chromatography system 102 also includes a peristaltic pump 134 that supplies a regenerant fluid from a regenerant supply 136 to the ion exchange device 130 and the waste output 132 along a regenerant flow path 124. The chromatography system 102 can also include a microprocessor 128. The use of the peristaltic pump 134 is to provide a regenerant to the ion exchange device 130, which enables a faster and more synchronized delivery approach for chemical suppression than using a conventional chromatography system.

[0019] A sample fluid (which can include a sample such as an analyte and an eluent) is supplied to the chromatography system 102 at a high-pressure input 126 along a sample flow path 122. The sample fluid passes through an injection valve 110 that can be activated to allow the sample fluid to pass through or deactivated to prevent the sample fluid from flowing along the sample flow path 122. The fluid can enter the high-pressure input 126 from a high-pressure pump and can include, for example, an eluent generated by an eluent generator.

[0020] The sample fluid flows through the guard column 104 along the sample flow path 122. The guard column 104 is a short column or cartridge installed before a chromatography separation device 106 such as an analytical column or a capillary column. The guard column 104 can act as a filter to prevent particles from entering the chromatography separation device 106 and can capture any chemical contaminants having a high affinity for the stationary phase. As a result, the guard column 104 ensures the integrity of the high-pressure or ultra-high pressure liquid chromatography (U)HPLC results and helps increase data reproducibility by removing chemical impurities that may prevent the chromatography separation device 106 from effectively retaining the target analyte from the sample. By retaining physical contaminants, the guard column 104 can increase the lifespan of the chromatography separation device 106 by reducing the chance of column blockage. In some embodiments, the guard column 104 is optional and can be omitted from the sample flow path 122.

[0021] The sample fluid flows through the chromatography separation device 106 (which may also be referred to as an analytical column). The chromatography separation device 106 can separate various matrix components present in the liquid sample from the target analyte. Typically, the chromatography separation device 106 can be in the form of a hollow cylinder containing a packed stationary phase. When the liquid sample flows through the chromatography separation device 106, the matrix components and the target analyte can have a range of retention times to elute from the chromatography separation device 106. Depending on the characteristics of the target analyte and the matrix components, they can have different affinities for the stationary phase of the chromatography separation device 106. The output of the chromatography separation device 106 can be fluidly connected to the ion exchange device 130.

[0022] The ion exchange device 130 can be used to reduce the conductivity background of the eluent and enhance the analyte response through efficient exchange of eluent counterions for regenerated ions. In some embodiments, the ion exchange device 130 can be a chemically regenerated suppressor. The ion exchange device 130 receives the sample fluid at the sample inlet 116 and outputs the sample fluid at the sample outlet 118. The ion exchange device 130 also receives the regenerator at the regenerator inlet 114 and outputs the regenerator at the regenerator outlet 120. In ion chromatography (IC) applications, the ion exchange device 130 enhances the conductivity signal of the analyte. Generally, the suppression reaction utilizes a regenerator source of ions supplied either externally or via a recycling mode, exchanging them with the eluent and sample counterions through an ion exchange transport mechanism, resulting in a suppressed eluent background with an improved analyte response. In various embodiments, the ion exchange device 130 can operate continuously when an external regenerator liquid source is supplied.

[0023] In some embodiments, the ion exchange device 130 suppresses the conductivity of the electrolyte in the eluent from the chromatography separation device 106, but does not suppress the conductivity of the separated ions (i.e., the sample). The conductivity of the separated ions is typically enhanced in the suppression process. For example, the exemplary anion Cl - This can be enhanced by converting it to an acid in the form of HCl. After passing through the ion exchange device 130, the eluent is neutralized to produce its weakly ionized form. For example, exemplary eluent OH -It can be neutralized by reacting it with hydronium ions to form water. Typically, the ion exchange device 130 includes a main channel connecting a sample inlet 116 and a sample outlet 118 through which ion species flow, and a regenerator channel connecting a regenerator inlet 114 and a regenerator outlet 120 through which a regenerator flows. The ion exchange device can be used for IC suppression, as well as sample pretreatment and other applications. It will therefore be understood that the main channel can direct the eluent by the flow of ion species, or alternatively, simply direct the liquid containing the ion species. An example of a suppressor suitable for use as an ion exchange device 130 in a chromatography system 102 of this disclosure is described in U.S. Patent Application No. 18 / 055,064, filed November 14, 2022, the entirety of which application is incorporated herein by reference.

[0024] One type of ion exchange device 130 is an electrolytic suppressor (sometimes referred to as a salt converter) comprising an anode chamber, a cathode chamber, and an eluent suppression bed chamber separated by an ion exchange membrane. The anode chamber and / or cathode chamber can generate or transport supplied regenerating ions. The eluent suppression bed chamber may include a channel for the eluent separated from the regenerator by an ion exchange barrier, and eluent counterions can exchange with regenerator ions across the ion exchange barrier. The electrolytic suppressor is recharged by supplying water to the regenerator inlet. Thus, the electrolytic suppressor is a class of ion exchange devices 130 that benefits from the use of a peristaltic pump 134, as the peristaltic pump 134 provides a regular and stable water source.

[0025] The sample outlet 118 can be fluidly connected to a detector 138 to measure the presence of separated chemical components in a liquid sample. Any ion exchange device 130 (e.g., a suppressor) known to those skilled in the art is suitable for this application, having multiple channels such as those configured.

[0026] In some embodiments, the chromatography system 102 may include a supply of check criteria that can reduce errors in measurements from the chromatography system 102 and / or calibrate measurements in the chromatography system 102. The supply of check criteria may be included in the sample flow path 122, for example, between the guard column 104 and the chromatography separation device 106. Some chromatography systems 102 according to this disclosure may include a recycling system for check criteria. Check criteria supplies and recycling systems compatible with the chromatography system 102 according to this disclosure are described in U.S. Patent Application Publication No. 2023 / 0075933, published on March 9, 2023, the entirety of which publication is incorporated herein by reference.

[0027] The detector 138 may include an ultraviolet-visible spectrometer, a fluorescence spectrometer, a refractive index detector, a radioflow detector, a chiral detector, an electrochemical detector, a conductivity detector, or any combination thereof. Preferably, the detector 138 is a non-destructive detector that substantially preserves the eluent flow received from the sample outlet 118 of the ion exchange device 130.

[0028] The sample fluid can flow from the detector 138 to one or more flow units 108. The flow units 108 can be separated by a back pressure coil 112. In some embodiments, after flowing through the flow units 108 and the back pressure coil 112, the sample fluid is delivered to a waste output 132. For example, the waste output may be a waste container or a drain (containing a neutralizing agent to control the acidity / alkalinity of the fluid before disposal).

[0029] The ion exchange device 130 receives the regenerator delivered by the peristaltic pump 134 along the regenerator channel 124. After the used regenerator leaves the regenerator outlet 120 of the ion exchange device 130, the used regenerator can proceed to a waste output 132 such as a drain or waste container.

[0030] The peristaltic pump 134 provides a stable supply of regenerator at low pressure to the ion exchange device 130. In some embodiments, the peristaltic pump 134 is quieter than other fluid delivery devices (e.g., provides less acoustic vibration), which allows for lower levels of fluid disturbance. The peristaltic pump 134 can distribute pulse-free or pulse-attenuated fluid from a regenerator supply unit 136, such as an external regenerator reservoir or bottle, to the ion exchange device 130 (e.g., a suppressor that is electrolytically or chemically regenerated). Since the peristaltic pump 134 draws fluid from the regenerator supply unit 136 at a constant, controllable rate, the fluid in the regenerator supply unit 136 can be brought to atmospheric pressure. By avoiding pressurizing the regenerator fluid, which may be caustic or corrosive, the use of the peristaltic pump 134 improves user safety by avoiding the possibility of user exposure to chemicals that may occur in a pressurized environment (i.e., unexpected bursting or explosion of liquid under pressure). In some embodiments, the peristaltic pump 134 provides the regenerator at low pressure. In some embodiments, the peristaltic pump 134 can deliver fluid at a fluid flow rate in the range of 0.1 to 10 mL / min.

[0031] In some embodiments, the peristaltic pump 134 is connected to a microprocessor 128 to enable direct control of the operation of the peristaltic pump 134 by the microprocessor 128. For example, the microprocessor 128 can operate the peristaltic pump 134 as a digitally interfaced variable flow controller having a wide linear dynamic flow rate delivery range, using a single set of pump tubing on a regenerator channel 124 having a constant bore diameter. In conventional systems, it has been difficult to dynamically change the flow rate of the regenerator because the tubing along the regenerator channel 124 must be removed and replaced with tubing having a larger or smaller bore diameter. In embodiments of this disclosure, the microprocessor 128 can control the fluid delivery rate of the peristaltic pump 134 by controlling the speed of the peristaltic pump 134. In some embodiments, the microprocessor 128 can control the flow rate of the regenerator with a single static operating value.

[0032] In some embodiments, the microprocessor 128 can automatically adjust the flow rate of the regenerator from the peristaltic pump 134 to optimize chemical results based on smart real-time analytical chemistry feedback data. For example, if the ion exchange device 130 is a chemical suppressor, suppression of the eluent conductivity can be performed dynamically by changing the concentration, flow rate, or both of the regenerator fluid. The microprocessor 128 can receive signals from the detector 138 or flow unit 108 indicating the conductivity of the eluent, and thus real-time analytical chemistry results. The microprocessor 128 can then control the peristaltic pump 134 to adjust the flow rate of the regenerator fluid, increasing or decreasing the conductivity until the conductivity measured by the detector 138 matches the desired conductivity. The microprocessor 128 can also address eluent gradient conditions according to specific usage methods of the instrument (e.g., operating methods stored in memory associated with the microprocessor 128). In some experiments, the eluent concentration may be changed by the user during a single run (e.g., from low to high, high to low). The microprocessor 128 can automatically adjust the flow rate of the peristaltic pump 134 based on measured or planned changes in eluent concentration to provide optimal suppression.

[0033] In some embodiments, the peristaltic pump 134 provides a regenerating fluid to the ion exchange device 130 during its active operation to exchange ions along the sample channel 122. In some conventional devices, the ion exchange device 130 is regenerated offline while disconnected from active use in chromatographic operation. The chromatography system 102 taught herein allows the ion exchange device 130 to be regenerated during active chromatographic operation without removing it from the sample channel 122.

[0034] In some embodiments, the sample channel 122 or regenerator channel 124 can be formed from a series of connected flow elements, including fluid tubes (e.g., polymer, metal, ceramic, or glass tubes). The fluid tubes can pass through the bodies of several components, such as the ion exchange device 130. The portion of the channel can include flexible tubes or chemical-resistant tubes. In some embodiments, the sample channel or regenerator channel can include a portion formed of polyvinyl chloride, such as Tygon® tubes. In some embodiments, the inner diameter of the regenerator channel can be constant along the entire length of the channel. In some embodiments, the inner diameter of the portion of the channel outside the apparatus can be constant, and / or the inner diameter can be selected independently of the desired flow rate. In some embodiments, the inner diameter of the flexible tube along the regenerator channel is selected to provide ripple-free performance and support a wide linear range of flow rates. In some conventional apparatuses, different flexible tubes can be placed in the channel to select the desired flow rate, with tubes of smaller inner diameters reducing the flow rate. As taught herein, a single set of flexible tubing can be used while adjustments are made to the peristaltic pump to vary the flow rate and provide ripple-free performance.

[0035] The back pressure coil 112 can provide a low-pressure limited outlet passage along the sample flow path 122 after the ion exchange device 130 or detector 138. The back pressure coil 112 can function to maintain a more stable flow through the preceding device and, in some cases, can reduce the size of bubbles along the route in the fluid flow. The flow unit 108 may include an additional detector (i.e., in addition to, and possibly complementary to, detector 138), or a coupler connecting the back pressure coils to each other, to detector 138, and to the waste output 132.

[0036] Figure 2 illustrates a perspective view of the peristaltic pump 134 in an open state according to various embodiments taught herein, allowing for the insertion, removal, or replacement of fluid tubing (e.g., a portion of the regenerator flow path 124). The peristaltic pump 134 includes the peristaltic pump 134, a mounting plate 210, and a motor casing 206. The peristaltic pump 134 may include an upper section 218 and a lower section 214. The fluid tubing passes through a guide 212 located between the upper section 218 and the lower section 214. The peristaltic mechanism 202 within the peristaltic pump 134 engages with a motor in the motor casing 206. When the motor drives the peristaltic mechanism 202 (e.g., a series of wheels or rollers orbiting a central point), the peristaltic mechanism 202 presses against the fluid tubing, causing the fluid to flow through the tubing. In particular, the fluid pipes can engage with the peristaltic mechanism 202 of the peristaltic pump 134 without the need to disconnect the ends of the fluid pipes (i.e., the pipes can be installed in or removed from the pump without disconnecting the regenerator flow path 124).

[0037] The peristaltic mechanism 202 can include several rollers appropriate to the needs of a particular application. In various configurations, the peristaltic mechanism 202 can include 3, 6, 8, or 12 rollers. In applications with a dual-head configuration (as described with respect to Figure 10 below), each pump head can use the same or a different number of rollers. The use of additional rollers can reduce noise in some examples. Due to the high sensitivity of the detector 138, some applications using very low flow rates (e.g., less than approximately 1.0 mL / min or less than approximately 0.5 mL / min) experience pressure ripple due to peristaltic pump pulsation. These ripples can generate high levels of noise (e.g., suppressed conductivity baseline noise) and degrade signal-to-noise performance. In one example, the electrical conductance noise and signal-to-noise ratio were compared between a pump head 204 with 3 rollers and a pump head 204 with 6 rollers. The results are shown in the table below. The six-roller configuration reduced the level of electrical conductance noise and increased the signal-to-noise ratio, especially at low flow rates.

[0038] [Table 1]

[0039] In some embodiments, the upper portion 218 may include a handle 216 to facilitate separation of the upper portion 218 from the lower portion 214. For example, the handle 216 can facilitate lifting the movable upper portion 218 relative to the stationary lower portion 214 (e.g., on a rail or hinge). Those skilled in the art will understand that other embodiments may include a handle 216 attached to the lower portion 214 rather than the upper portion 218 so that the lower portion 214 moves relative to the upper portion 218. In other embodiments, the handle 216 may be fixed to both portions, and / or the portions may move relative to each other.

[0040] The electrical connection section 208 extends from the motor casing 206 and connects the peristaltic pump 134 to a power supply, a microprocessor 128, or both. The motor casing 206 includes the motor itself (e.g., a brushless motor) which is connected to the peristaltic mechanism in the peristaltic pump 134 that applies pressure to fluid pipes to allow fluid to flow.

[0041] Figure 2 illustrates an open peristaltic pump 134 in which fluid tubes can be inserted, removed, or replaced, while Figure 3 illustrates the same peristaltic pump 134 in a closed, clamped state in which the peristaltic mechanism can engage with the fluid tubes.

[0042] Figure 4 illustrates an exploded view of the peristaltic pump 134. The fasteners 402 pass through the pump head 204 and attach to each of the mounting holes 412 of the mounting plate 210. For example, the fasteners 402 may include screws or bolts that connect to the threaded mounting holes 412 or pass through the mounting holes 412 and are secured by nuts on the back of the mounting plate 210.

[0043] The motor 406 extends from the motor casing 206 and engages with the peristaltic mechanism 202. In some embodiments, the peristaltic mechanism 202 may include one or more impellers or wheels that apply pressure to flexible fluid tubing while translating or rotating to push fluid through the tubing. During assembly of the peristaltic pump 134, the peristaltic mechanism 202 can extend through the through-hole 408 of the mounting plate 210 and enter the pump head 204. In some embodiments, the motor casing 206 may be secured to the mounting plate 210 through one or more spacers 410. The spacers 410 can provide an appropriate standoff distance (depending on the size of the motor 406 and / or peristaltic mechanism 202) to ensure that the peristaltic mechanism 202 seats properly within the pump head 204. The fasteners 404 can pass through the spacer holes 416 of the mounting plate 210 with each fastener 402 fixed to the end of each spacer 410.

[0044] In some embodiments, the mounting plate 210 can be fixed to the cabinet or case of the chromatography system 102 using mounting holes 414. In some embodiments, the pump head 204 is located outside the cabinet or case and is accessible to the user during normal operation, while the motor casing 206 is hidden inside the cabinet or case and is not accessible to the user during normal operation.

[0045] Figure 5 illustrates an inverted angle view of the peristaltic pump 134. The spacer 410 creates a standoff distance between the motor casing 206 and the mounting plate 210.

[0046] Figure 6 illustrates a cabinet-type chromatography system 102 having a peristaltic pump 134 mounted on the front panel of the chromatography system 102. In various embodiments, the peristaltic pump 134 can be mounted internally or externally (i.e., independently) to the chromatography system 102.

[0047] Figure 7 illustrates a graphical user interface (GUI 702) for a chromatography system 102 according to various embodiments taught herein. The GUI 702 may include various windows having graphical control and readout elements to enable control and display of system parameters or variables. In one embodiment, the results window 704 of the GUI 702 may include a flow chart or table that provides volumetric flow rate as a function of pump speed. The pump speed can be varied within the range of 0 to 100%. The use of the peristaltic pump 134 according to various embodiments taught herein can result in a linear relationship between pump speed and flow rate. This linear relationship increases predictability during incremental ramping. The incremental percentage setting of the pump motor can be programmed to align linearly with the amount of liquid flow being delivered and does not depend on the uniformity of the voltage level delivered to the pump motor. This represents an improvement over conventional pumps where the level of voltage supplied to the motor cannot be directly matched to the desired consistency of the flow. In some cases, the relationship between pump speed (e.g., controlled by the voltage applied to the pump) and flow rate may change over time due to softening of tubing or other structural changes after prolonged use, or due to environmental factors. To account for these changes, GUI702 can provide the user with control to achieve a target flow rate by modifying the slope of the curve defining the relationship between pump speed and flow rate. In some cases, GUI702 can provide the user with control to define a nonlinear relationship between pump speed and flow rate. In some cases, GUI702 can provide user control of flow rate, for example, by direct specification of the flow rate in mL / min. For example, the user can set the flow rate within the range of 0 mL / min to 10 mL / min.

[0048] Figure 8 includes plot 802 showing the results of a reproducibility experiment performed using the chromatography system 102 according to the embodiments described herein. In this experiment, seven analytes (fluoride, chloride, nitrite, bromide, nitrate, sulfate, and phosphate) are eluted through the chromatography system 102. Elution intensity peaks are measured as a function of time. The experiment is repeated 30 times, and the traces are superimposed to form plot 802. As illustrated in plot 802, there is a large overlap between chromatograms measured in different runs, and therefore little deviation between runs is observed. Since the peristaltic pump 134 provides a repeatable and controllable pump speed, variability between runs is strongly reduced, leading to reliable quantification of the data.

[0049] Figure 9A illustrates an exemplary chromatography system 102 including a carbonate removal device 902. In Figure 9A, the sample channel 122 is illustrated with a solid line, and the regenerator channel 124 is illustrated with a dashed line. The carbonate removal device 902 receives the sample fluid from the ion exchange device 130 (such as a suppressor) and sends the sample fluid to the detector 138. The peristaltic pump 134 supplies the regenerator fluid from the regenerator supply unit 136 to the ion exchange device 130 along the regenerator channel 124. The regenerator fluid then flows out of the ion exchange device 130 under pressure from the peristaltic pump and into the carbonate removal device 902. Finally, the regenerator fluid can exit the carbonate removal device 902 and flow to the waste output 132.

[0050] In some embodiments, the peristaltic pump 134 can supply a basic solution to a carbonate removal device 902 (CRD) or draw a vacuum across a gas-permeable membrane within the carbonate removal device 902. The gas-permeable membrane is designed to remove carbon dioxide gas from the sample fluid flow (analyte and eluent). The carbonate removal device 902 helps to provide low background conductivity and improved baseline noise, which can result in maximizing the signal-to-noise ratio of the target analyte. In some embodiments, the peristaltic pump 134 can draw a vacuum across the gas-permeable membrane to physically extract dissolved carbon dioxide gas from the eluent. In other embodiments, the peristaltic pump 134 can circulate a basic regenerator solution from the eluent through the compartment on the opposite side of the gas-permeable membrane to chemically extract dissolved carbon dioxide gas from the eluent and convert it to aqueous sodium carbonate.

[0051] Figure 9B illustrates a chromatography system 102 in which a peristaltic pump 134 is connected to an ion exchange device 130 along a first channel 904 and to a carbonate removal device 902 along a second channel 906. In some embodiments, the peristaltic pump 134 may have a dual-channel configuration that allows two sets of fluid tubing to be operated by a single peristaltic mechanism 202. Thus, the first channel 904 and the second channel 906 can be fluidically isolated from each other, while each simultaneously supplies fluid to components in the chromatography system 102. In various embodiments, the first channel 904 exiting the ion exchange device 130 and the second channel 906 exiting the carbonate removal device 902 can collect waste at the same or different waste outputs 132.

[0052] Figure 10 illustrates a chromatography system 102 including post-column reagent delivery according to several embodiments taught herein. In this embodiment, the regenerator channel 124 is similar to that described above with respect to Figure 1. However, the peristaltic pump 134 is a dual-head or dual-channel pump that operates the regenerator channel 124 and the reagent channel 1010. Post-column reagent delivery can enable additional forms of sensing or detection, such as detection based on ultraviolet light irradiation. The peristaltic pump 134 draws fluid containing the post-column reagent from the reagent supply unit 1006 along the reagent channel 1010. The reagent channel 1010 and the sample channel 122 merge together at the fluid junction 1008 to form the post-column channel 1012. The post-column channel 1012 flows through the reaction coil 1004. The reaction coil 1004 facilitates the reaction between any remaining analytes that could not be detected by the detector 138 and the post-column reagent. For example, the post-column reagent and the analyte can be chemically bonded together. The post-column channel 1012 then flows through an ultraviolet photodetector 1002, which irradiates the post-column channel 1012 with ultraviolet light and measures the response using a photodetector. The photoresponse can be proportional to the amount of analyte in the post-column channel 1012. The peristaltic pump 134 can supply a stable, ripple-free flow of the post-column reagent, while also providing a stable flow of the regenerator to an ion exchange device and / or a carbonate removal device (not shown).

[0053] For clarity, it should also be understood that certain features of the Disclosure described herein in the context of separate embodiments may be combined to provide a single embodiment. That is, unless obviously incompatible or excluded, each individual embodiment is considered combinable with any other embodiment, and such combination is considered a separate embodiment. Conversely, for brevity, various features of the Disclosure described in the context of a single embodiment may be provided separately or in any partial combination. It should be further noted that the claims may be drafted to exclude any optional element. Therefore, this statement is intended to serve as an antecedent for the use of exclusive terms such as "alone" or "only" in relation to the description of the claimed elements or the use of "negative" limitations. Finally, embodiments may be described as part of a series of steps or as part of a more general structure, but each such step may also be considered an independent embodiment in itself.

[0054] Where a list is given, unless otherwise specified, each individual element of that list and every combination of that list shall be understood to be construed as a separate embodiment. For example, a list of embodiments given as "A, B, or C" shall be construed as including embodiments "A", "B", "C", "A or B", "A or C", "B or C", or "A, B, or C".

[0055] While this disclosure illustrates several embodiments by description and describes these embodiments in considerable detail, the applicant does not intend to limit or restrict in any way the scope of the appended claims in this manner. Additional advantages and modifications may be readily apparent to those skilled in the art. Furthermore, features from separate lists can be combined, and features from the examples can be generalized throughout this disclosure.

Claims

1. It is an ion chromatography system, A chromatographic separation device for separating analytes in a sample fluid, An ion exchange device for receiving the sample fluid from the chromatography separation device, An ion chromatography system comprising a peristaltic pump for supplying a regenerating fluid to the ion exchange device.

2. The ion chromatography system according to claim 1, further comprising a non-pressurized regenerating agent supply unit.

3. The ion chromatography system according to claim 2, further comprising fluid tubes for transporting the regenerating fluid from the regenerating fluid supply unit to the ion exchange device, wherein the peristaltic pump can engage and disengage the flexible tubes while the flexible tubes are connected to the regenerating fluid supply unit and the ion exchange device.

4. The ion chromatography system according to claim 1, wherein the peristaltic pump supplies the regenerating fluid at a flow rate in the range of 0.1 to 10 mL / min.

5. The system further comprises a microprocessor that communicates with the peristaltic pump, and the microprocessor The ion chromatography system according to claim 1, configured to execute commands for controlling the flow rate of the regenerating fluid.

6. The ion chromatography system according to claim 5, wherein the command for controlling the flow rate includes controlling the speed of the peristaltic pump.

7. The aforementioned microprocessor The conductivity of the regenerating fluid is determined based on the signal received from the detector or flow unit. Dynamically controlling the flow rate to increase or decrease the conductivity, The ion chromatography system according to claim 5, further configured to execute commands to repeatedly perform the steps of determining the conductivity and dynamically controlling the flow rate until the conductivity matches a desired conductivity.

8. The ion chromatography system according to claim 5, wherein the microprocessor controls the flow rate of the regenerating fluid based on a measured or planned change in eluent concentration.

9. The aforementioned microprocessor The ion chromatography system according to claim 5, configured to execute further commands using a graphical user interface (GUI) to display a flow chart showing volumetric flow rate as a function of pump speed.

10. The ion chromatography system according to claim 1, further comprising a carbonate removal device.

11. The ion chromatography system according to claim 10, wherein the carbonate removal device receives a regenerating fluid from the ion exchange device under pressure from the peristaltic pump.

12. The ion chromatography system according to claim 10, wherein the peristaltic pump applies a vacuum to the gas permeable membrane of the carbonate removal device.

13. The ion chromatography system according to any one of claims 1 to 12, wherein the peristaltic pump is a dual-head or dual-channel peristaltic pump.

14. The peristaltic pump delivers the regenerating fluid along the first flow path, The ion chromatography system according to claim 13, wherein the peristaltic pump delivers the post-column reagent from the reagent supply unit along the second flow path to the fluid junction downstream of the ion exchange device.

15. A method for performing ion chromatography, In a chromatography separation device, the separation of analytes in a fluid sample, Using an ion exchange device, the conductivity of non-analyte electrolytes in the separated fluid sample is suppressed, Using a peristaltic pump, the regenerating fluid is supplied to the ion exchange device. A method comprising detecting the analyte in the separated fluid sample using a detector.

16. The method according to claim 15, wherein supplying a regenerating agent fluid includes obtaining the regenerating agent fluid from a regenerating agent supply unit maintained at atmospheric pressure.

17. The supply of the regenerating agent fluid further includes transporting the regenerating agent fluid in fluid tubes from the regenerating agent supply unit to the ion exchange device, and the method is The method according to claim 16, further comprising disengaging the peristaltic pump from the flexible tubes while the flexible tubes remain connected to the regenerating agent supply unit and the ion exchange device.

18. The method according to claim 15, wherein supplying the regenerating fluid includes moving the regenerating fluid at a flow rate in the range of 0.1 to 10 mL / min.

19. The method according to claim 15, further comprising using a microprocessor that communicates with the peristaltic pump to control the flow rate of the regenerating fluid.

20. The method according to claim 19, wherein controlling the flow rate includes using the microprocessor to control the speed of the peristaltic pump.

21. The conductivity of the regenerating fluid is determined based on the signal received from the detector or flow unit. Dynamically controlling the flow rate to increase or decrease the conductivity, The method according to claim 19, further comprising iteratively repeating the steps of determining the conductivity and dynamically controlling the flow rate until the conductivity matches a desired conductivity.

22. The method according to claim 19, wherein controlling the flow rate includes changing the flow rate in response to a measured or planned change in eluent concentration.

23. The method according to claim 19, further comprising using a graphical user interface (GUI) to display a flow chart showing volumetric flow rate as a function of pump speed.

24. The method according to claim 15, further comprising removing carbon dioxide gas from the separated fluid sample using a carbonate removal device.

25. The method according to claim 24, further comprising supplying a regenerating fluid from the ion exchange device to the carbonate removal device under pressure from the peristaltic pump.

26. The method according to claim 24, further comprising using the peristaltic pump to apply a vacuum to the gas permeable membrane of the carbonate removal device.

27. The peristaltic pump is a dual-head or dual-channel peristaltic pump. The supply of the regenerating fluid is performed along the first flow path, and the method is The method according to any one of claims 15 to 26, further comprising delivering a post-column reagent from a reagent supply unit along a second flow path to a fluid junction downstream of the ion exchange device.

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