Platinum electrode system

Abstract

A detection cell for a chromatography system, the detection cell comprising a cell body comprising a counter electrode in the form of a cell body or a wire; comprising a working electrode; a spacer separating the working electrode block from the cell body, the spacer defining a sample flow channel extending between the inlet and the outlet of the detection cell and being in fluid contact with the cell body, the counter electrode, and the working electrode; and a reference electrode system in contact with the outlet fluid and including a platinum auxiliary electrode operably connected to a positive electrode of a power source and a platinum reference electrode operably connected to a negative electrode of the power source.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention generally relates to flow-through detection cells for chromatographic detection, and more particularly, to solid-state reference electrodes and methods of using the same in such cells. SUMMARY OF THE INVENTION

[0002] Liquid chromatography analysis of compounds such as carbohydrates, amino acids, and related compounds occupies an important position among the tools used in the biotechnology industry, biochemical research, and clinical laboratories.

[0003] Using a liquid chromatography column in combination with pulsed electrochemical detection under alkaline conditions enables separation with unique selectivity and direct detection of analytes without derivatization with unparalleled sensitivity.

[0004] Until now, the common method for amperometric detection in highly alkaline mobile phases has been to use a gold working electrode, a platinum or titanium counter electrode, and a liquid reference electrode such as a silver-silver chloride electrode, a calomel electrode, a mercury-mercurous sulfate electrode, or a thallium amalgam-thallous chloride electrode.

[0005] However, during exposure to the alkaline eluents used in chromatographic carbohydrate and amino acid analysis, the reference potential of a silver-silver chloride reference electrode changes, usually with a positive shift. This results in an excessive potential being applied to the working electrode, leading to a gradual decrease in response and / or a narrowing of the linear range of the calibration curve. In extreme cases, the working electrode may be passivated, resulting in a decrease in detection sensitivity.

[0006] Other types of reference electrodes, such as calomel electrodes (mercury-mercurous chloride electrodes), mercury-mercurous sulfate electrodes, and thallium amalgam-thallous chloride electrodes electrodes) are affected by the alkaline eluents in a similar manner and affect the function of the working electrode in the same way.

[0007] In addition, with the increasing importance of capillary chromatography and hyphenated detection techniques, it is necessary to miniaturize the detection cell. More importantly, it is necessary to reduce the total cell dead volume of the electrochemical flow cell installed upstream of other detection cells. Otherwise, an excessive electrochemical cell dead volume results in a significant loss of peak efficiency in the downstream detection cell.

[0008] However, due to the space requirements and surface roughness of the liquid junction and the large volume of the reference electrode body, miniaturization of cells containing conventional common reference electrodes (such as silver / chloride or similar reference electrodes) is usually very difficult.

[0009] In addition, this type of reference electrode shows other problems, such as leakage of ions from the filled electrolyte solution, relatively short lifespan, and large total cell dead volume if used with such a reference electrode in a microelectrochemical detection cell.

[0010] On the other hand, solid-state reference electrodes can be more easily miniaturized for use in capillary electrochemical detection cells. The total cell dead volume can be significantly reduced so that this cell can be used before other detection cells. In addition, compared with silver / silver chloride reference electrodes, it also has some other advantages, such as longer lifespan, less maintenance, more durable and easy to use.

[0011] More importantly, solid-state reference electrodes do not leak any ions, such as potassium and chloride in silver / silver chloride reference electrodes. Therefore, multiple ED cells can be used in series, and ED can be combined with different detection techniques (such as ED-MS) to develop new applications.

[0012] The use of solid-state palladium-hydrogen reference electrodes has been described (see, for example, US 8,342,007). A constant DC power supply is connected to palladium and platinum to decompose water. Hydrogen is generated on the palladium electrode and oxygen is generated on the platinum electrode.

[0013] However, palladium has the ability to adsorb molecular hydrogen, and its volume expands after adsorbing hydrogen (Gileadi et al., Interfacial Electrochemistry: An Experimental Approach, Addison-Wesley, 1975, pp. 247–249), and is transformed into various forms of palladium hydride.

[0014] It is known that when hydrogen is adsorbed, there are three phases in palladium:

[0015] 1. The α-phase is fixed at an H:Pd atomic ratio x < 0.03 (PdHx).

[0016] 2. α / β (x: 0.03 - 0.59).

[0017] 3. The β-phase (x: > 0.59).

[0018] As Figure 1 shown, the potential diagram of the palladium hydride electrode only forms a plateau in the α / β phase. Therefore, as a reference electrode in the α / β phase, palladium hydride provides the best stable potential (Goffe et al., "Internal Charge Palladium Hydride Reference Electrode - Part 1: Effect of Charging Current Density on Long-Term Stability", Med. & Biol. Eng. & Comput., 1978, 16, 670 - 676).

[0019] Therefore, solid-state palladium hydride reference electrodes have some inherent defects:

[0020] 1. It takes a long time, two hours or more, to be ready for use.

[0021] 2. If used at extremely high concentrations of hydroxide (i.e., 1M NaOH), it may cause a shortened lifespan.

[0022] 3. The size increases after absorbing a large amount of hydrogen, and then palladium hydride is formed.

[0023] Accordingly, it is desirable to provide a solid-state reference electrode that can overcome at least some of the above problems.

[0024] The listing or discussion of a patent document that is clearly prior art in this specification is not necessarily to be taken as an admission that the document is part of the prior art or common general knowledge.

[0025] Accordingly, the present invention provides a flow-through detection cell for a chromatographic system, including a cell body having an inlet, an outlet, and a counter electrode, a working electrode, a sample flow channel extending between the inlet and the outlet and being in fluid contact with the counter electrode and the working electrode, and a platinum-hydrogen (Pt / H2) reference electrode system.

[0026] The detection cell can be a three-electrode detection system.

[0027] The cell body can be made of a conductive or non-conductive material. The cell body can be made of a corrosion-resistant metal or a conductive polymer. The cell body can be made of a material selected from the group consisting of titanium, corrosion-resistant alloys, stainless steel, carbon-loaded polyether ether ketone (PEEK), polythiophene, polyindole, and polynaphthalene.

[0028] The reference electrode system is a Pt / H2 reference electrode system. The reference electrode system includes a platinum (Pt) reference electrode and a platinum (Pt) auxiliary electrode, both the reference electrode and the auxiliary electrode being in fluid contact with the fluid sample flow channel. The reference electrode can be directly or indirectly connected to the negative electrode of a power source. The auxiliary electrode can be directly or indirectly connected to the positive electrode of a power source.

[0029] The detection cell may further include a gasket disposed between the counter electrode and the working electrode and having an opening that forms a thin-layer channel between the counter electrode and the working electrode, wherein the channel can be fluidly connected to the cell body inlet and outlet, thereby forming a part of the fluid sample channel.

[0030] The cell body may include an inlet and electrode cavities fluidly connected to the inlet and the outlet, thereby forming a part of the fluid sample flow channel. At least one of the platinum reference electrode and the platinum auxiliary electrode can be a wire. For example, the platinum (Pt) reference electrode can include a wire extending into a reference electrode hole of the cell body and being isolated by a non-wire (such as a polymer tube).

[0031] Another aspect of the present invention relates to a chromatography system comprising any of the above-described detection cells. The chromatography system may include a plurality of detection cells, where the detection cells may be arranged in series.

[0032] The methods and apparatuses of the present invention have other features and advantages that will be apparent from or more fully described in the accompanying drawings and the following detailed description, which are incorporated herein by reference to explain certain principles of the present invention.

[0033] The present invention will now be described with reference to the following non-limiting drawings and examples.

[0034] Brief Description of the Drawings

[0035] Figure 1 - Potential diagram of a palladium hydride electrode

[0036] Figure 2 - Side view of a thin-layer detection cell with a solid-state intrinsic Pt / H2 reference electrode installed

[0037] Figure 3 - Side view of an ED cell with a Pt / H2 reference electrode in a working electrode block group

[0038] Figure 4 - Side view of a cell with a Pt / H2 reference electrode in a counter electrode block group

[0039] Figure 5 - Schematic diagram of an exemplary detection cell for a chromatography system according to various aspects of the present invention

[0040] Figure 6 - Overlaid chromatograms obtained using new Pt / H2 and Ag / AgCl REs in the current ED cell: six monosaccharide mixture

[0041] Figure 7A and 7B - 40 consecutive chromatogram overlays obtained using Ag / AgCl ( Figure 7A ) and Pt / H2 ( Figure 7B ) reference electrodes

[0042] Figure 8A and 8B - 40 consecutive injection response stability plots obtained using Ag / AgCl ( Figure 8A ) and Pt / H2 ( Figure 8B ) reference electrodes

[0043] Figure 9- Overlaid chromatograms obtained using a new Pt / H2 reference electrode in a flow-through ED cell for the analysis of fluorodeoxyglucose (FDG), fluorodeoxymannose (FDM), and chlorodeoxyglucose (CDG): 0.5 ppm (solid line); 5 ppm (dotted line) and 50 ppm (dashed line)

[0044] Figure 10 - Typical chromatogram obtained using a new Pt / H2 reference electrode in a flow-through ED cell for streptomycin analysis: 1. System suitability peak (streptomycin thermal decomposition peak); 2. Streptomycin

[0045] Figure 11 - Typical chromatogram obtained using a new Pt / H2 reference electrode in a flow-through ED cell for the analysis of a monosaccharide and disaccharide mixture: 1. Glucose; 2. Fructose; and 3. Sucrose

[0046] Figure 12 - Typical chromatogram obtained using a new Pt / H2 reference electrode in a flow-through ED cell for the analysis of a seven-alcohol mixture: 1. Arginine; 2. Lysine; 3. Alanine; 4. Threonine; 5. Glycine; 6. Valine; 7. Serine; 8. Proline; 9. Isoleucine; 10. Leucine; 11. Methionine; 12. Histidine; 13. Phenylalanine; 14. Glutamic acid; 15. Aspartic acid; 16. Cystine; 17. Tyrosine; *: System peak

[0047] Figure 13 - Typical chromatogram obtained using a new Pt / H2 reference electrode in a flow-through ED cell for the analysis of a seven-alcohol mixture: 1. Sorbitol; 2. Glycerol; 3. Ethylene glycol; 4. Methanol; 5. Ethanol; 6. 1-Propanol; and 7. 1-Butanol (except 50 ppm, 100 pm for 1-butanol); *: Excluded volume

[0048] Detailed Description of the Invention

[0049] Reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. Although the present invention will be described in conjunction with exemplary embodiments, it should be understood that this description is not intended to limit the present invention to those exemplary embodiments. On the contrary, the present invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents, and other embodiments, which may be included within the scope of the present invention as defined by the appended claims.

[0050] Figure 2 An exemplary aspect of the present invention is shown, in which the Pt / H2 reference electrode is part of a three-electrode thin-layer detection cell.

[0051] The detection cell typically includes three electrodes. However, depending on various embodiments, configurations, and design considerations, the detection cell can have two or more electrodes. Older two - electrode designs used the same two electrodes (working electrode and reference electrode) to adjust voltage and measure current, while in a three - electrode cell, only the voltage between the reference electrode and the working electrode is adjusted. Current measurement is made between the working electrode and the counter electrode.

[0052] Some people refer to the counter electrode as the auxiliary electrode. However, in this article, the term "auxiliary electrode" specifically refers to the second, anode electrode of a two - electrode system of a Pt / H2 electrode. There are reports describing chromatographic detection cells with more than three electrodes, for example, cases where multiple working electrodes (referencing the same reference electrode) are included (LUNTE et al., "Differential - mode detection using thin - layer dual - electrode liquid chromatography / electrochemistry," Anal. Chem., 1985, Vol. 57, pp. 1541 - 1546). The Pt / H2 electrodes described herein can be used with all of the above - mentioned types of low - dead - volume chromatographic detection cells.

[0053] The detection cell of the present invention eliminates the need for a large reference electrode chamber required when using silver / silver chloride electrodes, and as Figure 2 shown, the relatively large silver / silver chloride reference electrode is replaced by a platinum wire (3) that is connected to the negative electrode (5) of a secondary power supply. The reference electrode system (Pt / Pt charged using a secondary DC power supply) requires a positively charged electrode preferably made of a platinum wire (2). The two platinum wires are insulated from each other and from the counter - electrode block (10) by a polymer sleeve. The new solid - state reference electrode is located in the same thin - layer flow path as the working electrode (6) and the counter electrode (10). The flow path (11) is defined by openings in the thin - film gaskets (9) and (9b).

[0054] Although the platinum reference electrode (3) and / or the auxiliary platinum electrode (2) are preferably in the form of platinum wires, the platinum reference electrode (3) and / or the auxiliary platinum electrode (2) can also be in the form of foils or tubular structures.

[0055] Typically, the detection cell will also include a yoke - knob assembly (not shown) for assembling the detection cell.

[0056] The materials for the cell body (10) suitable for use as a counter electrode include, but are not limited to, titanium, high-quality stainless steel, or durable highly conductive polymers. On the other hand, suitable materials for the cell body not used as a counter electrode include, but are not limited to, polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), polychlorotrifluoroethylene (Kel-F), and polycarbonate. The cell body is preferably machined or otherwise formed to include an inlet (7) and an outlet (1), the inlet (7) and the outlet (1) being fluidly connected to a thin-layer channel (11) to form a fluid sample flow line. Preferably, the inlet, channel, and outlet are configured to minimize the dead volume within the detection cell. In the illustrated configuration, the thin-layer path of the cell is formed by the channels of the gasket; however, it will be understood that the thin-layer path of the cell can be formed by microgrooves machined within the body of the conductive counter electrode.

[0057] For the purposes of the present invention, a thin-layer channel is a channel having a volume in the range of about 1 pL to about 100 μL, such as about 1 pL to 1 μL. The following ranges of flow path dimensions (either within the gasket or as precision-machined microgrooves) can be used to form a low-volume, thin-layer flow path. The overall dimensions of the flow path can include a width of about 0.01 mm to about 6 mm, such as about 0.1 mm to about 3 mm, a length of about 3 mm to about 24 mm, such as about 6 mm to about 12 mm, and a thickness of about 0.001 mm to about 1.0 mm, such as about 0.0125 to about 0.5 mm. Preferably, its width is about 0.5 - 2 mm, its length is about 6 - 10 mm, and its thickness is about 0.0125 - 0.25 mm. Most preferably, its width is about 0.5 - 1.5 mm, its length is about 6 - 9 mm, and its thickness is about 0.0125 - 0.05 mm.

[0058] The yoke-knob assembly allows for the rapid assembly and disassembly of the detection cell in other known ways. Specifically, the yoke-knob assembly includes a yoke for aligning the working electrode (6) with the gasket (9) and thus with the cell body (10), such that the working electrode, gasket, and cell body are sealingly engaged with each other. It will be understood that the yoke-knob assembly can be configured to provide a consistent sealing force to the working electrode, such as a pressure of about 1 to 15 lb / in2, to properly and reliably maintain the sealing effect of the gasket on the working electrode and the cell body.

[0059] As previously mentioned, compared to prior detectors including relatively large silver / silver chloride reference electrodes, the detection cell of the present invention includes a platinum / platinum (Pt / Pt) reference electrode system.

[0060] In Figure 2 the platinum (Pt) hydrogen reference electrode system (2, 3) extends into the reference electrode bore of the conductive cell body (10, counter electrode) isolated by a polymer tube (14). The reference electrode (3) is directly or indirectly connected to the negative electrode (5) of a suitable power source.

[0061] As described in detail above, the reference electrode system includes an auxiliary platinum electrode (2) to complete the reference electrode system (2, 3). The auxiliary electrode is positively charged and is directly or indirectly connected to the positive electrode (4) of a suitable power source.

[0062] In operation and use, the detection cell is used in a manner similar to that of known detectors having a conventional silver / silver chloride reference electrode. For example, the platinum reference electrode (3) and the platinum auxiliary electrode (2) are connected to a power source having the Figure 2 polarity shown. In addition, the platinum reference electrode (3) is connected to the electronic circuitry of the three-electrode detection system in other conventional ways as a reference electrode. In a preferred configuration, the auxiliary electrode (2) is located downstream of the working electrode (6) and the platinum reference electrode (3), and the platinum reference electrode (3) is located downstream of the working electrode (6).

[0063] A Pt / H2 reference electrode is generated by applying a power source potential connected to the platinum reference electrode (3) and the platinum auxiliary electrode (2). Preferably, the potential is less than about 10 V, more preferably about 1.25 - 2 V, and most preferably about 1.5 - 1.7 V. In addition, the potential is substantially constant, that is, it undergoes oscillations and / or other voltage variations of less than about 10 mV, more preferably less than about 0.1 mV, and most preferably less than about 0.001 mV.

[0064] Relative to an Ag / AgCI reference electrode and a Pt / H2 reference electrode immersed in the same solution, the platinum reference electrode provides a hydrogen electrode that provides a stable reference potential.

[0065] The actual difference in reference values can be measured using any of a variety of suitable methods. For example, for any new detection experiment, the correct adjustment values for direct current amperometry and pulsed electrochemical potential can be identified by achieving a baseline signal level and similar peak areas that are approximately the same as those of the silver / silver chloride reference electrode. Alternatively, the reference potential of the Pt / H2 reference electrode can be evaluated by comparison with a conventional silver / silver chloride electrode in a second detection cell located downstream of the first detection cell.

[0066] Alternatively, the Pt / H2 reference electrode can also be located within the working electrode block (8), which is different from the Figure 2 design shown (see Figure 3 ). One advantage of this design is that the Pt / H2 reference electrode can be regenerated by polishing it together with the working electrode, thereby extending the life of the reference electrode.

[0067] Finally, the Pt / H2 reference electrode can be implemented as a reference electrode module that includes two platinum wires that are very close to each other

[0068] (see Figure 4)。Two platinum wires are inserted into the same polymer tube (12), such as a double lumen tube with two holes, while being isolated from each other. Such a reference electrode module can be made to fit the counter electrode and be flush with the counter electrode body in a flow-through electrochemical cell. The reference electrode is well isolated from the counter electrode (10). The Pt / H2 reference electrode configuration is compact, which can shorten the length of the thin layer flow path (11). Therefore, the total cell dead volume of the flow cell is further minimized, making it more likely to prevent the deterioration of the chromatographic performance of the downstream detector.

[0069] Advantageously, the present invention provides a Pt / H2 reference electrode that can be easily miniaturized for use in a chromatographic detection cell. The present invention also contemplates a Pt / H2 reference electrode suitable for a capillary system with the extreme requirement of minimizing dead volume.

[0070] The reference electrode system of the present invention generates a stable reference potential that does not change when exposed to the eluent or mobile phase used in the chromatographic separation process. In addition, the reference electrode assembly of the present invention does not exude any ions that interfere with the normal operation of other detectors connected downstream.

[0071] The construction of the reference electrode assembly of the present invention allows for a stable reference potential to be obtained during long-term exposure to an alkaline column eluent. Advantageously, an excessive detection potential is not accidentally applied to the working electrode, resulting in a downward trend in the detection response over time or a narrowing of the linear range of the calibration curve.

[0072] Since the Pt / H2 reference electrode does not include the same liquid junction as a typical liquid reference electrode, no electrolyte flows out of the reference electrode (e.g., chloride ions flowing out of a silver / silver chloride electrode). Generally, compared with conventional silver / silver chloride reference electrodes and other liquid type reference electrodes, the reference electrode assembly of the present invention provides a longer effective life.

[0073] The Pt / H2 reference electrode can be implemented as a reference electrode assembly comprising a platinum reference electrode (3) and a platinum auxiliary electrode (2), each electrode in the form of a wire and very close to each other. Such a reference electrode system can be installed in an existing reference electrode chamber designed for a conventional silver / silver chloride reference electrode.

[0074] For example, the reference electrode system a can be configured to replace the large reference electrode cartridge of an existing detection cell, such as the reference electrode cartridge of ED provided by Thermo Fisher Scientific in Waltham, Massachusetts, as shown in the operator's manuals of ICS-6000 and other ICS series ion chromatography systems (Dionex ICS-6000 ion chromatography system operator's manual, document number 22181-97002, revision 01, February 2018). The entire content of the ICS-6000 system manual is incorporated herein by reference.

[0075] In Figure 5 Another exemplary embodiment of the present invention as shown, the detection cell includes a cell body (10) having a threaded reference electrode cavity (14), a working electrode block ( Figure 4 8 in Figure 4 and a gasket ( 9 in

[0076] disposed between the cell body and the working electrode block. The inlet (7) is in fluid communication with the bottom of the threaded reference electrode cavity. The detection cell may be equipped with a reference electrode housing that is fixed within the threaded reference electrode cavity to position the electrode end in electrical contact with the fluid sample line.

[0077] The reference electrode housing may be fixed within the cavity (14) by a locking nut (11), which allows the reference electrode housing to be releasably fixed within the cell body (10). It should be understood that the electrode housing may be releasably or permanently fixed within the cavity by other suitable means, including but not limited to a retaining gasket, a press-fit, a bayonet fit or cap, welding, etc.

[0078] A reference electrode gasket (13) may be provided to define a thin layer channel extending between the platinum reference electrode (3) and the platinum auxiliary electrode (2). Similar to the above gasket ( Figure 4 9 in

[0079] The foregoing description of specific exemplary embodiments of the invention has been presented for purposes of illustration and description. The foregoing description is not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application, thereby enabling those skilled in the art to make and utilize various exemplary embodiments of the invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the appended claims and their equivalents.

[0080] For the avoidance of doubt, in this specification, when the term "comprising" is used, it means that the detection cell or system must include the listed components, but may optionally include additional components. Comprising shall be considered to include the term "consisting of", where the detection cell or system must include only the listed components.

[0081] For the avoidance of doubt, unless the context otherwise indicates, the preferences, options, specific features, etc. indicated for a given aspect, feature, or parameter of the present invention shall be considered to have been disclosed in combination with: any and all other preferences, options, and specific features, etc. indicated for the same or other aspects, features, and parameters of the present invention.

[0082] As used herein, the term "about", when referring to a measurable value (such as a quantity or parameter), means a variation of ±20%, ±10%, ±5%, ±1%, ±0.5%, or specifically ±0.1% of the specified amount.

[0083] Example

[0084] As shown in the table, the equipment used in the following experiments was purchased from Thermo Fisher Scientific, and the detailed information can be found in the relevant product catalogs.

[0085] Examples obtained using a prototype reference electrode on the current ED cell

[0086] Example 1: Analysis of a six-monosaccharide mixture

[0087] Using the conditions and cell implementation of Table 1, all chromatograms were generated using an ICS-5000 + system ( Figure 5 ). Data exemplifying the performance of a new Pt / H2 reference electrode installed in the reference chamber of a current-flow-through electrochemical cell for chromatographic detection are shown in Figure 6 , 7A , 7B, 8A, and 8B and Table 2.

[0088] Table 1: Experimental conditions for the analysis of a six-monosaccharide mixture

[0089]

[0090] 'System control and data processing: Thermo Scientific Dionex 7.2 software

[0091] Table 2. Comparison of the performance of Ag / AgCl and Pt / H2 reference electrodes

[0092]

[0093] *: Ratio = Prototype RE Response / Ag / AgCI RE Response **: n = 3

[0094] Example 2: Analysis of Fluorodeoxyglucose (FDG), Fluorodeoxymannose (FDM), and Chlorodeoxyglucose (CDG)

[0095] Using the conditions and cell implementation of Table 3, chromatograms were generated with the ICS-6000 system ( Figure 5 ). Chromatograms demonstrating the performance of the new PT / H2 reference electrode installed in the reference chamber of a flow-through electrochemical cell for chromatographic detection are shown as Figure 9 follows.

[0096] Figure 3 : Experimental conditions for the analysis of fluorodeoxyglucose (FDG), fluorodeoxymannose (FDM), and chlorodeoxyglucose (CDG)

[0097]

[0098] * System control and data processing: Thermo Scientific Dionex 7.2 software

[0099] Example 3: Analysis of Streptomycin

[0100] Using the conditions and cell implementation of Table 4, chromatograms were generated with the ICS-6000 system ( Figure 2 ). Chromatograms demonstrating the performance of the new PT / H2 reference electrode installed in the reference chamber of a flow-through electrochemical cell for chromatographic detection are shown as Figure 10 follows.

[0101] Table 4: Experimental conditions for the analysis of streptomycin

[0102]

[0103]

[0104] * System control and data processing: Thermo Scientific Dionex 7.2 software

[0105] Example 4: Analysis of a mixture of monosaccharides and disaccharides

[0106] Using the conditions and cell implementation of Table 5, chromatograms were generated with the ICS-6000 system ( Figure 2 ). Chromatograms demonstrating the performance of the new PT / H2 reference electrode installed in the reference chamber of a flow-through electrochemical cell for chromatographic detection are shown as Figure 11 follows.

[0107] Table 5: Experimental Conditions for Monosaccharide and Disaccharide Analysis

[0108]

[0109]

[0110] * System Control and Data Processing: Thermo Scientific Dionex 7.2 Software

[0111] Example 5: Analysis of 17 Amino Acids

[0112] Using the conditions and cell implementation of Table 6, chromatograms were generated using the ICS-6000 system ( Figure 5 ). Chromatograms demonstrating the performance of the new PT / H2 reference electrode installed in the reference chamber of a flow-through electrochemical cell for chromatographic detection are shown as Figure 12 shown.

[0113] Table 6: Experimental Conditions for 17 Amino Acid Analysis

[0114]

[0115] * System Control and Data Processing: Thermo Scientific Dionex 7.2 Software

[0116] Example ⑥: Analysis of Six Alcohol Mixtures

[0117] Using the conditions and cell implementation of Table 7, chromatograms were generated using the ICS-6000 system ( Figure 5 ). Chromatograms demonstrating the performance of the new PT / H2 reference electrode installed in the reference chamber of a flow-through electrochemical cell for chromatographic detection are shown as Figure 13 shown.

[0118] Table 7: Experimental Conditions for Seven Alcohol Mixture Analysis

[0119]

[0120] * System Control and Data Processing: Thermo Scientific Dionex 7.2 Software.

Claims

1. A detection cell for a chromatography system, the detection cell comprising: A cell body including a counter electrode in the form of a cell body or a wire; A working electrode block including a working electrode; A gasket that separates the working electrode block from the cell body, the gasket defining a sample flow channel extending between an inlet and an outlet of the detection cell and being in fluid contact with the cell body, the counter electrode, and the working electrode; And A reference electrode system that is in fluid contact with the outlet and includes a platinum auxiliary electrode operably connected to the positive electrode of a power source and a platinum reference electrode operably connected to the negative electrode of the power source.

2. The detection cell according to claim 1, wherein the detection cell is a three-electrode detection system.

3. The detection cell according to claim 1, wherein the cell body is formed of a conductive material or a non-conductive material.

4. The detection cell according to claim 1, wherein the cell body is formed of a corrosion-resistant metal or a conductive polymer and a non-conductive polymer.

5. The detection cell according to claim 4, wherein the cell body is formed of a conductive material selected from the group consisting of titanium, corrosion-resistant alloys, stainless steel, carbon-loaded polyether ether ketone (PEEK), polythiophene, polyindole, and polynaphthalene, and is formed of a non-conductive material selected from the group consisting of polytetrafluoroethylene (PTFE), polyether ether ketone (PEEK), chlorotrifluoroethylene polymer (Kel-F), and polycarbonate.

6. The detection cell according to claim 1, wherein the reference electrode system includes a solid-state reference electrode.

7. The detection cell according to claim 1, wherein the platinum reference electrode and the platinum auxiliary electrode are in electrical contact with the fluid sample channel.

8. The detection cell according to claim 7, wherein the reference electrode includes a wire extending into a reference electrode hole in the cell body.

9. The detection cell according to claim 1, wherein the cell body includes an electrode cavity in fluid communication with the inlet and the outlet, thereby forming a part of the fluid sample channel.

10. The detection cell according to claim 9, wherein at least one of the Pt / H2 reference electrode and the platinum auxiliary electrode is a wire.

11. A chromatography system including the detection cell according to claim 1.

12. A chromatography system including the detection cell according to claim 9.

13. A chromatography system including a plurality of detection cells according to claim 1, wherein the detection cells are arranged in series.

14. A detection cell for a chromatography system, the detection cell comprising: A cell body; A working electrode block including a working electrode; A sample channel extending between an inlet and an outlet of the detection cell and being in fluid contact with the cell body and the working electrode; A counter electrode in fluid contact with the sample channel; And A reference electrode system that is in fluid contact with the outlet and includes an auxiliary electrode operably connected to the positive electrode of a power source and a Pt / H2 reference electrode operably connected to the negative electrode of the power source.

15. The detection cell according to claim 14, wherein the cell body is formed of a conductive material.

16. The detection cell according to claim 14, wherein the Pt / H2 reference electrode and the auxiliary electrode are in electrical contact with the sample channel, and the auxiliary electrode includes a platinum electrode.

17. The detection cell according to claim 14, wherein the Pt / H2 reference electrode comprises a wire extending into a reference electrode hole of the cell body.

18. The detection cell according to claim 14, wherein the reference electrode system operates at a potential below about 10 V and the voltage variation is less than about 10 mV.

19. The detection cell according to claim 14, wherein the channel has a volume of about 1 pL to 100 μL.

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