CA1232016A - Antimony and graphite hydrogen ion electrode - Google Patents
Antimony and graphite hydrogen ion electrodeInfo
- Publication number
- CA1232016A CA1232016A CA000487702A CA487702A CA1232016A CA 1232016 A CA1232016 A CA 1232016A CA 000487702 A CA000487702 A CA 000487702A CA 487702 A CA487702 A CA 487702A CA 1232016 A CA1232016 A CA 1232016A
- Authority
- CA
- Canada
- Prior art keywords
- antimony
- graphite
- antimony oxide
- electrode
- sensor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/28—Electrolytic cell components
- G01N27/30—Electrodes, e.g. test electrodes; Half-cells
- G01N27/308—Electrodes, e.g. test electrodes; Half-cells at least partially made of carbon
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/28—Electrolytic cell components
- G01N27/30—Electrodes, e.g. test electrodes; Half-cells
- G01N27/333—Ion-selective electrodes or membranes
Abstract
ABSTRACT
A solid state electrode that includes a graphite core as both the internal reference and the electrical conductor that is preferably formed of graphite threads maintained as a bundle that in one embodiment, has an end thereof coated with a mixture of antimony and antimony oxide as a sensor element, the graphite junction forming the internal reference to that sensor element, and in another embodiment, the graphite core is wrapped tightly around a sensor formed from section or "shot" of a mixture antimony and antimony oxide, the graphite junction forming the internal reference thereto. The connected graphite core and antimony/antimony oxide sensor are then covered with an impermeable non-conductive plastic sheath, leaving a section of the antimony/antimony oxide sensor surface exposed, and the junction of that sheath to the antimony/antimony oxide sensor is preferrably sealed as with an epoxy.
A solid state electrode that includes a graphite core as both the internal reference and the electrical conductor that is preferably formed of graphite threads maintained as a bundle that in one embodiment, has an end thereof coated with a mixture of antimony and antimony oxide as a sensor element, the graphite junction forming the internal reference to that sensor element, and in another embodiment, the graphite core is wrapped tightly around a sensor formed from section or "shot" of a mixture antimony and antimony oxide, the graphite junction forming the internal reference thereto. The connected graphite core and antimony/antimony oxide sensor are then covered with an impermeable non-conductive plastic sheath, leaving a section of the antimony/antimony oxide sensor surface exposed, and the junction of that sheath to the antimony/antimony oxide sensor is preferrably sealed as with an epoxy.
Description
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Background of the Invention Field of the Invention-This invention relates to electrodes for use in measuring hydrogen ion concentration that use antimony as the electrode's sensing element, and in particular it relates to pit electrodes for measuring acidity in stomach fluids.History of The Invention:
The present invention involves a solid state electrochemically ion selective electrode system preferably for measuring the pal of solutions, especially stomach fluids, and it relates to using untreated graphite and a pal sensing material (graphite/metal) as a novel internal reference electrode system.
There is a long-felt need in the health care industry for a relatively inexpensive and yet stable electrode for accurately measuring the hydrogen ion concentration, or phi of stomach secretions. This is especially relevant in the care of acutely ill or traumatized patients who frequently die from bleeding gastric ulcers produced by stress. These ulcers are the result of an abnormally high concentration of hydrogen ions in the stomach fluid, and may be diagnosed from the presence of a low phi Such patients' stomach pi should therefore be monitored continuously over a period of several days in order that their ulcers may be controlled by effective medication. Unfortunately, such monitoring has not heretofore been practical due to the pi electrodes that have been available. An electrode to effectively meet patient needs should: be small and flexible enough to be inserted with minimal patient discomfort; give a stable pi reading over a period of three to four days; and be inexpensive to construct. A need for such an electrode is clearly demonstrated from an examination of current methods of bleeding ulcertreatment.
Ulcer treatment has generally been based on raising the pi of the stomach fluids through the use of antacids. Antacids are administered when stomach fluid samples, taken periodically, become too acidic.
There are currently three methods of measuring gastric phi 1) Electrochemically by a pi electrode placed in aspirated stomach fluid;
Background of the Invention Field of the Invention-This invention relates to electrodes for use in measuring hydrogen ion concentration that use antimony as the electrode's sensing element, and in particular it relates to pit electrodes for measuring acidity in stomach fluids.History of The Invention:
The present invention involves a solid state electrochemically ion selective electrode system preferably for measuring the pal of solutions, especially stomach fluids, and it relates to using untreated graphite and a pal sensing material (graphite/metal) as a novel internal reference electrode system.
There is a long-felt need in the health care industry for a relatively inexpensive and yet stable electrode for accurately measuring the hydrogen ion concentration, or phi of stomach secretions. This is especially relevant in the care of acutely ill or traumatized patients who frequently die from bleeding gastric ulcers produced by stress. These ulcers are the result of an abnormally high concentration of hydrogen ions in the stomach fluid, and may be diagnosed from the presence of a low phi Such patients' stomach pi should therefore be monitored continuously over a period of several days in order that their ulcers may be controlled by effective medication. Unfortunately, such monitoring has not heretofore been practical due to the pi electrodes that have been available. An electrode to effectively meet patient needs should: be small and flexible enough to be inserted with minimal patient discomfort; give a stable pi reading over a period of three to four days; and be inexpensive to construct. A need for such an electrode is clearly demonstrated from an examination of current methods of bleeding ulcertreatment.
Ulcer treatment has generally been based on raising the pi of the stomach fluids through the use of antacids. Antacids are administered when stomach fluid samples, taken periodically, become too acidic.
There are currently three methods of measuring gastric phi 1) Electrochemically by a pi electrode placed in aspirated stomach fluid;
2) Visual color matching of litmus paper, exposed to aspirated stomach fluid;
3) Electrochemically by an indwelling stomach pi electrode.
35 The first two techniques do not provide instant information or "real-time" data for the physician, as they must be taken after the stomach fluid has been removed and ~Z32(~16 are costly due to the labor involved in acquiring a fresh sample of stomach fluid for each measurement.
An fllternative to frequent stomach fluid sampling has been to administer cimetidine, a substance which prevents the histamine induced release of acid into the stomach as set out in R. Herman and DO Kaminski, "Evaluation-of Intragastric pi in Acutely Ill Patients", Arch. Sung. 114, 511-514, 1979. Currently in such treatment there is no satisfactory method of monitoring pi which will give physicians immediate data on the patient's response to the cimetidine. Cimetidine is admistered until there is an indication from periodic stomach samples that bleeding has stopped. As a result, the patient may be receiving insufficient or excess amounts of simetidine. One problem with this line of treatment is that there is insufficient experimental evidence available to describe possible side-effects from over-administration of cimetidine. Finally, the cost of administering cimetidine is currently about twice as high as conventional antacid treatment, and therefore determination of minimum effective levels through immediate response monitoring as is provided by the present invention would benefit the cost of patient care as well as preventing possibly unknown side-effects.
A third method of monitoring gastric fluid pi is direct measurement with an indwelling pew electrode that will give the physician an immediate accurate reading of pi values. With this procedure, various modes of treatments can be assessed rapidly and safe dosage levels can be established with accuracy. Two main types of indwelling pi electrodes that are currently in use are constructed of either glass or antimony. Current glass pi electrodes appropriate for gastric analysis, are fragile and expensive to produce and transport. Such electrodes exhibit a high electrical resistance resulting in a protracted time response. A general discussion of some earlier antimony electrodes for measuring the acidity of stomach secretions is set out in: Err, ARC and Senior, CLUE.: J. Am. Osteopath. Assoc. 38, go, 1938;
and Haggard, HOW., and Greenberg, LEA.: Science 93, 479, 1941.
Prior Art:
The use of an antimony electrode as a pew sensor was first reported in 1923, A. Uhl and W. Krestanek, "Die Elektrometrische Titration Vonsauren and Basin mix don Antimon-indikatorelektrode", Sitzungsberichte d. mathem.-naturw.
do., At. Jib, 132, 29, 1923. As set out therefore, electrodes were made of an antimony sensor connected directly to a copper wire, and the electrode was enclosed 35 in a glass tube except for the exposed antimony sensor. This basic design has been reviewed in JUT. Stock, WACO. Purred and LAM. Garcia, "The Antimony-Antimony 1~32~)~6 Oxide Electrode", Chum. Rev. 58, 611-62~, 1958. These electrodes remained essentially unchanged for a considerable time despite their inherent instability. A
micro electrode version thereof has been described in, G. Manic and FLY. Voyeur,"The Antimony Micro electrode in Kidney Micro puncture", Yale J. Blot. Med. go, 35~-367, 1972.
More recently, several improvements in antimony electrodes have been reported that yield more stable results. One such electrode involves an antimony micro electrode that utilizes a silver/silver chloride internal reference system that was described in I Bicker and S. Okay, "Intracellular pi Electrode Experiments on the Giant Squid Axon", Become. Buffs. Act 255, 900-904, 1972.
This electrode consists of a glass tube containing an exposed antimony sensor electrochemically connected to a silver/silver chloride wire by a solution of potassium chloride.
I. Klein berg in, "Antimony Electrodes and Methods of Manufacturing Same," US. Patent No. 3,742,594, 1973, sets out the importance of using epoxy instead of glass to electrically insulate an antimony sensor from an electrical lead.
The patent recognizes the antimony contains micro crevices, and these crevices are thought to produce channels for water and electrolytes and thereby short-circuit the electrical potential changes that are due to a change in phi Therein, the use of a silver wire between the antimony and a copper electrical lead was stressed, but its importance as a standard internal reference system was not described. Whereas, the present invention utilizes untreated graphite both as the conductor and as the internal reference at the junction of that graphite to an antimony sensor. In addition, production of the Klein burg electrode requires precision soldering of the antimony micro-rods to a silver wire.
Recently it was determined that the design of Klein berg could be further improved by using elaborately prepared single crystals of antimony or monocrystalline antimony, NAGOYA. Ed wall and GAS. Eklund, "Monocrystalline Metal Electrode and Method of Use", US. Patent No. 4,119,498; 1978. Production of thisEd wall electrode, however, requires extremely precise measurements and manipulations of monocrystalline antimony, and minor flaws in the antimony crystal structure will cause the electrode to inaccurately sense changes in phi Such electrode is therefore very labor intensive and is extremely expensive to produce.
The accuracy and stability of antimony electrodes generally has been attributed to the stability of a defined internal reference system that involves a reversible electrochemical system based on well established reduction-oxidation 3.Z32(~6 principles. Such has been detailed in, J. Risque and COG. Lam, "Electrode for Potentiometric Measurements", US. Patent No. 3,926,765; 1975. This patent teaches an electroc}lemically active redo system that is sensitive to ions in solutioll, and a humid, solid, water soluble compound which acts as a carrier for this redo system. The importance of this internal reference system was demonstrated in Klein berg by a substitution of a silver for a copper wire, which substitution resulted in an extremely stable electrode.
Antimony pi electrodes that utilize a standard internal reference system are commercially available. One such antimony pi electrode is marketed byDiamond Electro-Tech Inc., (Ann Arbor, MI) and is available in either a miniature tip size (1 mm diameter) or a micro tip size (80 em diameter). Unlike the present invention, each of these electrodes use a silver wire as the standard internal reference electrode system. Another antimony pi electrode is commercially available from Marco Electronic, Ltd. (Winnipeg, Manitoba, Canada). This electrode also utilizes silver as the internal reference system and includes epoxy to seal the micro crevices between a plastic sheath and the antimony that is similar to the electrode taught in, I. Klein berg, "Antimony Electrodes and Methods of Manufacturing Same", US. Patent No. 3,742,594; 1973.
Where other pi electrodes have used materials other than antimony for the pi sensor, such have consistently taught the use of silver as the material of a standard internal reference junction therewith. For example, the metal palladium (Pod) will respond to pit changes and has been used as an electrode sensor element.
Such palladium electrodes have used an internal reference junction made of silver.
This is set out in, ISLE. Coon, N.C.J. Let and JO Company, "Evaluation of a Dual-Function pi and PCO2 ln-Vivo Sensor", J. Apply Fishily. 40: 625-629, 1976.
Another type of pi sensor that includes a non-metal embedded in plastic and usessilver as the internal reference system is set out in, OH. LeBlanc, Jr., JO Brown, Jr., JO Club, LOW. Niedrach, G.M.J. Sluxarczuk and WOW. Stoddard, Jr., "Polymer Membrane Sensors for Continuous Intravascular Monitoring of Blood pi", J. Apply Fishily. 40, 644-647, 1976. A more recent reference that teaches a use of silver in conjunction with one of its salts or the reduced metal salt (e.g. silver black) to produce a stable electrode system is set out in, JURY. Kiter, "Ion-Selective Electrodes", US. Patent No. 4,34D,457; 1982. This patent teaches adding silver black and platinum black to a standard internal reference system, like that set out in Risque, and is employed in order to enhance electrode stability.
123Z(~
An exception to the above wherein is taught a use of a well-defined standard internal reference electrode system is shown in Fig. 5. of a patent by, I.
Binder and HA. Teats, Jr., "An All Solid State Electrode System", US. Patent No.~,338,1~5; 19~2. It is, however, not possible to evaluate the preferred internal5 reference system from the description given in this patent. Unlike the presentinvention however, the electrode system of this patent is configured for use in mining and mineral processing and the electrode system itself is contracted of two electrodes; one made of a noble metal that functions as the reference electrode,with the other made of ultra-pure antimony that is sensitive to fluctuations in ion I levels in a solution whose pi is to be measured. This electrode is very expensive to construct as the antimony must be ultra-pure (99.999~6 antimony, as a less pure grade will not give stable and reproducible pi readings. Application of this arrangement as an indwelling pi electrode is therefore not practical due to its complexity and its use of expensive metals.
The present inventors have used graphite in an ion-sensitive electrode as an internal reference system when that graphite is appropriately chemically treated with a coating of a silencing agent, HUM. Brown, Jr. and JO Owen, "idea State Graphite Electrode", US. Patent No. 4,431,508;1984. This patent, however, does not teach, as does the present invention that graphite which has not been 20 chemically or physically altered will form a stable internal reference system when coupled with a metal pi sensor, that is preferably an antimony/antimony oxide section.
The present invention differs from the above-cited references and patents, as set out above, in a number of significant ways. It does not require a 25 labor-intensive mono-crystalline antimony manipulation. Instead its practice can involve a number of different forms of polycrystalline antimony that are easily mixed together and are preferably joined either during or after that mixing process to a body formed of untreated graphite fibers that are joined in a bundle, the graphite at the junction functioning as an internal reference system. The electrode 30 of the present invention, therefore, does not require a use of silver for either connection between an antimony sensor and an electrical lead, as do a number of the earlier electrodes. The electrode of the present invention can be used convenien$1y in conjunction with a standard potentiometer and a standard electrocardiogram ERG lead which forms the external reference electrode. The electrodes can be 35 designed for minimal patient discomfort, are inexpensive to construct, and are disposable. also, the electrode of the present invention requires no recalibration ~232(~
thereby reducing labor costs associated with measuring stomach fluid phi making it far less expensive to produce and to use than earlier antimony electrodes.
Summary of the Invention It is, therefore, a general objective of the present invention to provide 5 a solid state electrode that is suitable for use for measuring a patient's stomach fluid phi It is another objective of the invention to provide an indwelling antimony pi stomach fluid electrode which uses a graphite/metal junction as an internal reference system.
It is another objective of the invention is to provide an electrode which is extremely flexible to minimize discomfort when it is inserted into the patient's stomach.
It is another objective of the invention to provide a stable solid state electrode that will accurately monitor the pi of stomach fluids over a test period of 15 a number of days of an average hospital stay.
It is still another objective of the invention to provide a solid-state electrode which does not require calibration prior to use.
It is still another objective of the invention to provide an electrode which can be easily and inexpensively constructed.
In accordance with the above objectives, the present invention is in an indwelling electrode for measuring stomach fluid pi that consists of an antimonysensor that is connected directly to a bundle of graphite fibers. The graphite/metal junction providing the electrode internal reference. The assembly is then electrically insulated except for an exposed end surface of the antimony sensor, as 25 by a plastic sheath or tube shrunk fit there over and may include an epoxy seal there between.
The electrode is preferably formed to have a small diameter facilitating its insertion with minimal patient discomfort into a patient's stomach.
Without conditioning, the electrode will measure as an internal reference electrode 30 a change in hydrogen ion concentration reflective of a pi change as an electrical potential which potential is sensed across the antimony and graphite junction and registers at a monitoring device. The electrode is connected between a patient'sbody that functions as an external reference for the electrode, and a voltage measuring device. So arranged the electrode will faithfully sense and transmit to 35 the voltage measuring device a voltage presence over a test period of a number of days that is the average patient hospital stay. In practice, when maintained in a ~32(~1~
solution of known pi simulating a patient's stomach fluid, an embodiment of the invention continued to give a stable pi reading even after several days.
The invention provides an electrode for use in measuring hydrogen ion concentration comprising a graphite core; an antimony/antimony oxide sensor secured in electrical contact with the graphite core and having an exposed surface for immersion in a test solution; and means for electrically isolating the graphite core and antimony/
antimony oxide sensor junction from the test solution when the antimony/antimony oxide exposed surface is immersed therein.
The invention further provides a process for manufacturing an antimony and graphite hydrogen ion electrode comprising the steps of, connecting a section of graphite to an antimony/antimony oxide sensor so as to provide an internal reference junction; connecting that section of graphite to an electrical conductor; encasing the graphite and antimony/antimony oxide sensor junction and the electrical conductor in a liquid impervious sheath so as to leave a portion of the sensor exposed; and connecting the electrical conductor to an electrically conductive lead.
Brief Description of the Drawings These and other objects will appear in the following detailed description in which preferred embodiments have been described in detail in conjunction with the accompanying drawings.
Fig. 1 is a side elevation sectional view of a first embodiment of an antimony and graphite electrode of the present invention;
Fig. 2 is a side elevation sectional view of a second embodiment of an antimony and graphite electrode of the present invention;
Fig. 3 is a graph comparing pi readings of the 1232(~1L6 antimony electrode of the present invention with those of a conventional glass electrode in the same solutions, demonstrating the ability of the present invention to accurately measure pi over a broad range;
Fig. 4 is a graph comparing pi readings of antimony electrodes of the present invention maintained in the same solutions with a conventional glass electrode demonstrating the reliability of the antimony electrode over a period of several days; and Fig. 5 is a graph comparing the antimony electrode of the present invention with a copper/antimony electrode in the same solution over time.
Detailed Description Referring now to the drawings:
Earlier electrodes appropriate for sensing hydrogen ion concentration have generally involved a solid electron chemically active redo system to produce a stable electrode potential. Such a redo system has typically been a mercury and mercury chloride (calmly), or silver and silver chloride.
The electrode of the present invention does not require such internal redo system, and in fact, employs only a section of an untreated graphite that is in contact and forms an electrically conductive junction with a sensor of antimony Sub functioning as an internal reference for the electrode.
The basic electrode of the present invention is illustrated in Figs. 1 and 2 as consisting of a bundle of untreated graphite threads that are wrapped around or otherwise connected to a cylindrical section of piece of antimony/antimony oxide. The antimony/graphite junction that forms the internal reference for the electrode is then covered by shrink fitting a plastic sheath thereto that can then be sealed as with an epoxy arranged between the antimony end edge -pa-~23~
and sheath wall to seal out moisture while leaving the antimony face exposed. Soarranged, the antimony/antimonv oxide section will function as the sensing element, the graphite at the graphite/antimony junction acting as the internal reference system with the untreated graphite above this junction functioning as a flexibleelectrical conductor.
The preferred untreated graphite and antimony/antimony oxide used in the construction of the electrode are inexpensive. The antimony used to manufacture the antimony/antimony oxide sensor need only be technical grade, which costs about a penny per electrode, and the preferred graphite will cost about two cents per foot. In practice a graphite manufactured by Hercules Corporation's known as Magnamite h&s be found to work satisfactorily and consists of a thin flexible bundle of graphite fibers, the bundle containing approximately one thousand individual thin graphite fibers maintained together. The small diameter of the bundle facilitates its insertion, with minimal discomfort or harm, through a patient's throat and into their stomach. The graphite fibers in each bundle are small; (approximately seven microns 7 x 10 6 meters) in diameter and when wrapped together form as the bundle a small thread of graphite that has a tensile strength of about 400,000 pounds per square inch. This is approximately twenty times the tensile strength of a copper wire of the same diameter. The electrode has a longstorage life and can be taken off the shelf and used immediately without conditioning, special treatment or preparation. In addition, calibration of the electrode is generally unnecessary as all electrodes that are of similar construction, will provide a measure of pi accurate to within + 0.5 pi units which is more than sufficient accuracy for intragastric measurements.
A preferred method of electrode construction involves drawing molten antimony/antirmony oxide into a thin glass capillary tube of a diameter of approximately 1.7 x lo mm., and allowing it to slowly cool until solid. The glass capillary is then broken away from the brittle antimony oxide rod, which itself can then be easily broken into smaller pieces to make individual electrodes. Such slow cooling of the molten antimony will promote large crystal growth which enhances the stability of the pi electrode, as set out in G. Ed wall, "Influence of Crystallographic Properties on Antimony Electrode Potential I. Polycrystalline Material," Electrochim. Act 24, 595-603,1979.
Fig. l shows a side elevation sectional view of a first embodiment of an antimony and graphite hydrogen ion electrode lo of the present invention hereinafter referred to as electrode lo Electrode lo is preferably constructed by 1232(~16 tightly wrapping a "bundle" of untreated graphite threads 11 around a section, "shot"
or rod of antimony/antimony oxide 12 that is untreated and is covered with impermeable plastic sheath 13 such as one formed from a polyvinyl chloride (PVC)plastic that can be heat shrunk thereto, so as to leave exposed an 5 antimony/antimony oxide tip end 14.
In Fig. 2 is shown a side elevation sectional view of an alternate or second embodiment of the antimony undo graphite hydrogen ion electrode 20 of thepresent invention, hereinafter referred to as electrode 20. Electrode 20 also incorporates untreated graphite threads 21 but involves dipping or otherwise coating 10 an end thereof with a molten mixture of antimony/antimony oxide 22, which coating and the threads above the coating are then covered with an impermeable plastic sheath 23 that is also preferably polyvinyl chloride (PVC) so as to leave exposed an antimony/antimony oxide tip end 24. The electrodes 10 and 20 are each capable ofaccurately measuring hydrogen ion concentrations or pi of aqueous solutions. In 15 each electrode the graphite at the junction with the antimony/antimony oxide sensor functions as an internal reference, with the graphite there above functioning as a conductor. Therefore, it should be understood that that portion of the graphite that functions as a conductor could be replaced with another electrically conductive material such as a copper wire, or the like, within the scope of this disclosure.
20 Either electrode 10 or 20, when connected between a patient's body, that functions as an external reference electrode, and a potentiometer or like voltage measuring device, will continue to provide an accurate measurement of solution pi over a period of a number of days as will be discussed hereinafter with respect to Figs. 3 through 5, allowing the electrode to remain within a patient's stomach over the 25 period of an average patient hospital stay, which period, in practice, is three to four days.
Both the electrode 10 and 20 of Figs. 1 and 2 preferably include encasing the electrode in a sheath of an impermeable plastic tubing 13 and 23 tocover the graphite/antimony junction so as to leave the antimony/antimony oxide tip 30 end 14 or 24 exposed, and each electrode preferably includes an epoxy seal, shown at 15 in Fig. 1 and 25 in Fig. 2, that is coated around the junction of the sheath with the antimony tip edge to provide a moisture tight barrier or seal between the plastic sheath and that antimony/antimony oxide electrode tip. So arranged, each antimony/antimony oxide tip end 14 or 24 will be exposed to allow it to directly35 contact a solution whose pi is to be measured. The electrodes 10 and 20 are preferably encased by plastic sheath 13 and 23 over their length, with ends 16 and 26 1232(~16 thereof, respectively, of each connected to a conductive wire 17 of 27, or the like, that is, in turn, connected to a potentiometer, or like voltage potential measuring device, not shown.
A preferred method of constructing the electrode lo of Fig. l, involves drawing molten antimony/antimony oxide heated to a molten state into a thin glass capillary tube, a preferred tube measuring approximately 1.7 x l00 mm., and allowing that mixture to slowly cool until solid. Antimony segments or rods are then obtained by breaking the glass tubes from there around. The metal rods are then themselves broken into individual cyc1indrical sections or "shots" and are in turn, connected to the graphite fibers by wrapping the fibers tightly around the rod section so as to form the graphite-antimony/antimony oxide interface. The preferred graphite is the Hercules Magnamite~ identified above, that is formed as a thread or bundle from approximately one thousand (1,000) graphite fibers, each fiber being approximately seven microns (7 x lo 6 meters) in diameter. Preferably, a bundle of 1000 of these graphite fibers is used for each electrode. After the antimony/antimony oxide tip is secured thereto, the bundle is covered with a tubular section of polyvinyl chloride (PVC) heat-shrink plastic tubing that is heated to shrink to the bundle, forming an electrical insulator there over, while leaving an antimony/antimony oxide tip end surface uncovered. Thereafter, an epoxy is preferably applied between the exposed antimony/antimony oxide tip end edges junction with the tubing inner circumference forming a moisture proof seal. The opposite end of the electrode is then ready for connection to a conductive lead that, in turn, is connected to a potentiometer, or like electrical potential measuringdevice. The potentiometer is, also connected by a separate line, such as a standard electrocardiogram ERG lead, to the patient's skin, the patient functioning in the loop as an external reference electrode. Such ERG Reads are specially designed for minimal patient discomfort, are relatively inexpensive and are disposable. The electrode so formed has been found in practice to work without preconditioning, to provide an accurate measure of the presence of hydrogen ions in solution.
Another preferred construction procedure used to produce the electrode 20, includes a utilization of elemental powdered antimony that is obtained in bulk. This powdered antimony, as in the fabrication of the electrode lo of Fig. l, is heated to melting in a ceramic beaker to approximately 700 Celsius, and that temperature is maintained, (the melting temperature of antimony is 630.7~ Celsius) thus forming a mixture of antimony (Sub) and antimony oxide (SbO3).
The presence of antimony oxide (SbO3) is necessary to provide an effective sensor ~Z32(~
tip for accurately sensing hydrogen ion concentration and passing that sensed concentration, as a voltage potential, across the internal reference junction of the sensor tip into the contacting graphite. After melting, the antimony/antimony oxide mixture is used to construct the electrode of Fig. 2, by dipping the untreated graphite bundle end directly into the molten antimony/antimony oxide, removing that end therefrom, and allowing the antimony/antimony oxide that remains thereon to cool and harden. Usually one dipping of the bundle of fibers in the molten antimony/antimony oxide mixture will provide a sufficient coating that, when it is allowed to cool and solidify, will produce a very thin layer of antimony/antimony oxide bonded to the graphite fibers. Thereafter the bundle is encased within theplastic tubing 23, leaving an antimony/antimony oxide end 24 surface exposed, and any space between the edge of that end and the plastic tubing inner circumference is sealed at 25 by application of an epoxy, or the like, thereto.
The graphite/antimony interface of electrode 20 like that of electrode 10, will function as an internal reference, passing an electrode potential to a voltage measuring device that remains consistent over a significant time period. The antimony electrode potential can be referred to as a corrosion potential, and, although it is not thoroughly understood, it is believed to be mainly governed by the following two equations as set out in, M. Markdahl~Bjarme and G. Ed wall, "Modified Conventional Type of pCO2-Electrode With Monocrystalline Antimony as the pH-sensing Element", Med. Blot. Erg. Compute 19, 447-456,1981.
2Sb + 3H20~Sb203 + OH + ye and 0 + OH+ + 4 - ` OH 0 That the graphite/antimony electrode will perform as a pi electrode is demonstrated in Fig. 3. Therein, the open circles (o) show the change in potential (my) of a graphite/antimony electrode as compared with a change irk potential 30 measured by a conventional glass pi electrode in the same solution identified as closed circles (o).
In it 4 the long-term stability of two separate graphite/antimony electrodes is compared with that of a standard gloss pi electrode. The graph shows that, over a period of two and one-half days, the apparent pi of the graphite-35 antimony electrodes was identical and only a difference of 0.2 pi unit was seen -lo-~23Z(~ 6 after four and one half days, with the glass pi electrode shown to have drifted about 0.1 pi unit over that four and one-half day period.
Fig. 5 Chavez vertical lines bisecting open (o) and closed (~) circles that indicate, respectively, copper/antimony and graphite/antimony electrodes, the 5 length of the vertical lines indicating the variance in pi values obtained from three individual antimony/graphite electrodes as compared to equivalent data from electrodes with antimony/copper junctions, utilizing a ply 2 solution. The data was obtained over 150 hours of recording. The bars represent the standard deviation,with a range of acceptable error for gastric analysis, of + 0.5 pi unit. From an10 inspection of Fig. 5, the antimony/graphite electrodes showed a small drift of about -0.25 pi unit for the initial 10 hours, with an apparent change of only .05 pi unit during the period from 25-150 hours, that is well within the range of acceptableerror. Whereas, the copper/antimony electrodes are shown to have drifted appreciably at the 10 hour point and continued to drift badly thereafter. It i 15 obvious from Fig. 5 that the standard deviation of readings from the antimony/graphite electrode of any single data point is very "tight" compared to the readings from the copper/antimony electrodes. In practice, and as has been set out in the earlier cited patent by NAGOYA. Ed wall, and US Eklund, "Monocrystalline little Electrode and Method of Use", US. Patent No. 4,119,498; 1978, the 20 characteristics of low drift and small standard deviation can be further enhanced by a slower cooling of the antimony in a practice of fabricating the electrode of the present invention.
While hereinabove have been detailed preferred embodiments of antimony/antimony electrodes and a process for their manufacture, it should be 25 understood that the electrode of the invention can be formed by processes different from those described and that other configurations or arrangements of untreated graphite and even different types of untreated graphite can be used from those set out herein within the scope of this disclosure so long as the graphite/antimony junction is "tight" to produce the required internal reference junction. It should, 30 therefore, be understood that the present disclosure is made by way of example only and that changes in the electrode construction from the preferred embodiments and in the outlined processes of manufacture, can be made without departing from thesubject matter conning within the scope of the following claims, which claims weregard as our invention.
35 The first two techniques do not provide instant information or "real-time" data for the physician, as they must be taken after the stomach fluid has been removed and ~Z32(~16 are costly due to the labor involved in acquiring a fresh sample of stomach fluid for each measurement.
An fllternative to frequent stomach fluid sampling has been to administer cimetidine, a substance which prevents the histamine induced release of acid into the stomach as set out in R. Herman and DO Kaminski, "Evaluation-of Intragastric pi in Acutely Ill Patients", Arch. Sung. 114, 511-514, 1979. Currently in such treatment there is no satisfactory method of monitoring pi which will give physicians immediate data on the patient's response to the cimetidine. Cimetidine is admistered until there is an indication from periodic stomach samples that bleeding has stopped. As a result, the patient may be receiving insufficient or excess amounts of simetidine. One problem with this line of treatment is that there is insufficient experimental evidence available to describe possible side-effects from over-administration of cimetidine. Finally, the cost of administering cimetidine is currently about twice as high as conventional antacid treatment, and therefore determination of minimum effective levels through immediate response monitoring as is provided by the present invention would benefit the cost of patient care as well as preventing possibly unknown side-effects.
A third method of monitoring gastric fluid pi is direct measurement with an indwelling pew electrode that will give the physician an immediate accurate reading of pi values. With this procedure, various modes of treatments can be assessed rapidly and safe dosage levels can be established with accuracy. Two main types of indwelling pi electrodes that are currently in use are constructed of either glass or antimony. Current glass pi electrodes appropriate for gastric analysis, are fragile and expensive to produce and transport. Such electrodes exhibit a high electrical resistance resulting in a protracted time response. A general discussion of some earlier antimony electrodes for measuring the acidity of stomach secretions is set out in: Err, ARC and Senior, CLUE.: J. Am. Osteopath. Assoc. 38, go, 1938;
and Haggard, HOW., and Greenberg, LEA.: Science 93, 479, 1941.
Prior Art:
The use of an antimony electrode as a pew sensor was first reported in 1923, A. Uhl and W. Krestanek, "Die Elektrometrische Titration Vonsauren and Basin mix don Antimon-indikatorelektrode", Sitzungsberichte d. mathem.-naturw.
do., At. Jib, 132, 29, 1923. As set out therefore, electrodes were made of an antimony sensor connected directly to a copper wire, and the electrode was enclosed 35 in a glass tube except for the exposed antimony sensor. This basic design has been reviewed in JUT. Stock, WACO. Purred and LAM. Garcia, "The Antimony-Antimony 1~32~)~6 Oxide Electrode", Chum. Rev. 58, 611-62~, 1958. These electrodes remained essentially unchanged for a considerable time despite their inherent instability. A
micro electrode version thereof has been described in, G. Manic and FLY. Voyeur,"The Antimony Micro electrode in Kidney Micro puncture", Yale J. Blot. Med. go, 35~-367, 1972.
More recently, several improvements in antimony electrodes have been reported that yield more stable results. One such electrode involves an antimony micro electrode that utilizes a silver/silver chloride internal reference system that was described in I Bicker and S. Okay, "Intracellular pi Electrode Experiments on the Giant Squid Axon", Become. Buffs. Act 255, 900-904, 1972.
This electrode consists of a glass tube containing an exposed antimony sensor electrochemically connected to a silver/silver chloride wire by a solution of potassium chloride.
I. Klein berg in, "Antimony Electrodes and Methods of Manufacturing Same," US. Patent No. 3,742,594, 1973, sets out the importance of using epoxy instead of glass to electrically insulate an antimony sensor from an electrical lead.
The patent recognizes the antimony contains micro crevices, and these crevices are thought to produce channels for water and electrolytes and thereby short-circuit the electrical potential changes that are due to a change in phi Therein, the use of a silver wire between the antimony and a copper electrical lead was stressed, but its importance as a standard internal reference system was not described. Whereas, the present invention utilizes untreated graphite both as the conductor and as the internal reference at the junction of that graphite to an antimony sensor. In addition, production of the Klein burg electrode requires precision soldering of the antimony micro-rods to a silver wire.
Recently it was determined that the design of Klein berg could be further improved by using elaborately prepared single crystals of antimony or monocrystalline antimony, NAGOYA. Ed wall and GAS. Eklund, "Monocrystalline Metal Electrode and Method of Use", US. Patent No. 4,119,498; 1978. Production of thisEd wall electrode, however, requires extremely precise measurements and manipulations of monocrystalline antimony, and minor flaws in the antimony crystal structure will cause the electrode to inaccurately sense changes in phi Such electrode is therefore very labor intensive and is extremely expensive to produce.
The accuracy and stability of antimony electrodes generally has been attributed to the stability of a defined internal reference system that involves a reversible electrochemical system based on well established reduction-oxidation 3.Z32(~6 principles. Such has been detailed in, J. Risque and COG. Lam, "Electrode for Potentiometric Measurements", US. Patent No. 3,926,765; 1975. This patent teaches an electroc}lemically active redo system that is sensitive to ions in solutioll, and a humid, solid, water soluble compound which acts as a carrier for this redo system. The importance of this internal reference system was demonstrated in Klein berg by a substitution of a silver for a copper wire, which substitution resulted in an extremely stable electrode.
Antimony pi electrodes that utilize a standard internal reference system are commercially available. One such antimony pi electrode is marketed byDiamond Electro-Tech Inc., (Ann Arbor, MI) and is available in either a miniature tip size (1 mm diameter) or a micro tip size (80 em diameter). Unlike the present invention, each of these electrodes use a silver wire as the standard internal reference electrode system. Another antimony pi electrode is commercially available from Marco Electronic, Ltd. (Winnipeg, Manitoba, Canada). This electrode also utilizes silver as the internal reference system and includes epoxy to seal the micro crevices between a plastic sheath and the antimony that is similar to the electrode taught in, I. Klein berg, "Antimony Electrodes and Methods of Manufacturing Same", US. Patent No. 3,742,594; 1973.
Where other pi electrodes have used materials other than antimony for the pi sensor, such have consistently taught the use of silver as the material of a standard internal reference junction therewith. For example, the metal palladium (Pod) will respond to pit changes and has been used as an electrode sensor element.
Such palladium electrodes have used an internal reference junction made of silver.
This is set out in, ISLE. Coon, N.C.J. Let and JO Company, "Evaluation of a Dual-Function pi and PCO2 ln-Vivo Sensor", J. Apply Fishily. 40: 625-629, 1976.
Another type of pi sensor that includes a non-metal embedded in plastic and usessilver as the internal reference system is set out in, OH. LeBlanc, Jr., JO Brown, Jr., JO Club, LOW. Niedrach, G.M.J. Sluxarczuk and WOW. Stoddard, Jr., "Polymer Membrane Sensors for Continuous Intravascular Monitoring of Blood pi", J. Apply Fishily. 40, 644-647, 1976. A more recent reference that teaches a use of silver in conjunction with one of its salts or the reduced metal salt (e.g. silver black) to produce a stable electrode system is set out in, JURY. Kiter, "Ion-Selective Electrodes", US. Patent No. 4,34D,457; 1982. This patent teaches adding silver black and platinum black to a standard internal reference system, like that set out in Risque, and is employed in order to enhance electrode stability.
123Z(~
An exception to the above wherein is taught a use of a well-defined standard internal reference electrode system is shown in Fig. 5. of a patent by, I.
Binder and HA. Teats, Jr., "An All Solid State Electrode System", US. Patent No.~,338,1~5; 19~2. It is, however, not possible to evaluate the preferred internal5 reference system from the description given in this patent. Unlike the presentinvention however, the electrode system of this patent is configured for use in mining and mineral processing and the electrode system itself is contracted of two electrodes; one made of a noble metal that functions as the reference electrode,with the other made of ultra-pure antimony that is sensitive to fluctuations in ion I levels in a solution whose pi is to be measured. This electrode is very expensive to construct as the antimony must be ultra-pure (99.999~6 antimony, as a less pure grade will not give stable and reproducible pi readings. Application of this arrangement as an indwelling pi electrode is therefore not practical due to its complexity and its use of expensive metals.
The present inventors have used graphite in an ion-sensitive electrode as an internal reference system when that graphite is appropriately chemically treated with a coating of a silencing agent, HUM. Brown, Jr. and JO Owen, "idea State Graphite Electrode", US. Patent No. 4,431,508;1984. This patent, however, does not teach, as does the present invention that graphite which has not been 20 chemically or physically altered will form a stable internal reference system when coupled with a metal pi sensor, that is preferably an antimony/antimony oxide section.
The present invention differs from the above-cited references and patents, as set out above, in a number of significant ways. It does not require a 25 labor-intensive mono-crystalline antimony manipulation. Instead its practice can involve a number of different forms of polycrystalline antimony that are easily mixed together and are preferably joined either during or after that mixing process to a body formed of untreated graphite fibers that are joined in a bundle, the graphite at the junction functioning as an internal reference system. The electrode 30 of the present invention, therefore, does not require a use of silver for either connection between an antimony sensor and an electrical lead, as do a number of the earlier electrodes. The electrode of the present invention can be used convenien$1y in conjunction with a standard potentiometer and a standard electrocardiogram ERG lead which forms the external reference electrode. The electrodes can be 35 designed for minimal patient discomfort, are inexpensive to construct, and are disposable. also, the electrode of the present invention requires no recalibration ~232(~
thereby reducing labor costs associated with measuring stomach fluid phi making it far less expensive to produce and to use than earlier antimony electrodes.
Summary of the Invention It is, therefore, a general objective of the present invention to provide 5 a solid state electrode that is suitable for use for measuring a patient's stomach fluid phi It is another objective of the invention to provide an indwelling antimony pi stomach fluid electrode which uses a graphite/metal junction as an internal reference system.
It is another objective of the invention is to provide an electrode which is extremely flexible to minimize discomfort when it is inserted into the patient's stomach.
It is another objective of the invention to provide a stable solid state electrode that will accurately monitor the pi of stomach fluids over a test period of 15 a number of days of an average hospital stay.
It is still another objective of the invention to provide a solid-state electrode which does not require calibration prior to use.
It is still another objective of the invention to provide an electrode which can be easily and inexpensively constructed.
In accordance with the above objectives, the present invention is in an indwelling electrode for measuring stomach fluid pi that consists of an antimonysensor that is connected directly to a bundle of graphite fibers. The graphite/metal junction providing the electrode internal reference. The assembly is then electrically insulated except for an exposed end surface of the antimony sensor, as 25 by a plastic sheath or tube shrunk fit there over and may include an epoxy seal there between.
The electrode is preferably formed to have a small diameter facilitating its insertion with minimal patient discomfort into a patient's stomach.
Without conditioning, the electrode will measure as an internal reference electrode 30 a change in hydrogen ion concentration reflective of a pi change as an electrical potential which potential is sensed across the antimony and graphite junction and registers at a monitoring device. The electrode is connected between a patient'sbody that functions as an external reference for the electrode, and a voltage measuring device. So arranged the electrode will faithfully sense and transmit to 35 the voltage measuring device a voltage presence over a test period of a number of days that is the average patient hospital stay. In practice, when maintained in a ~32(~1~
solution of known pi simulating a patient's stomach fluid, an embodiment of the invention continued to give a stable pi reading even after several days.
The invention provides an electrode for use in measuring hydrogen ion concentration comprising a graphite core; an antimony/antimony oxide sensor secured in electrical contact with the graphite core and having an exposed surface for immersion in a test solution; and means for electrically isolating the graphite core and antimony/
antimony oxide sensor junction from the test solution when the antimony/antimony oxide exposed surface is immersed therein.
The invention further provides a process for manufacturing an antimony and graphite hydrogen ion electrode comprising the steps of, connecting a section of graphite to an antimony/antimony oxide sensor so as to provide an internal reference junction; connecting that section of graphite to an electrical conductor; encasing the graphite and antimony/antimony oxide sensor junction and the electrical conductor in a liquid impervious sheath so as to leave a portion of the sensor exposed; and connecting the electrical conductor to an electrically conductive lead.
Brief Description of the Drawings These and other objects will appear in the following detailed description in which preferred embodiments have been described in detail in conjunction with the accompanying drawings.
Fig. 1 is a side elevation sectional view of a first embodiment of an antimony and graphite electrode of the present invention;
Fig. 2 is a side elevation sectional view of a second embodiment of an antimony and graphite electrode of the present invention;
Fig. 3 is a graph comparing pi readings of the 1232(~1L6 antimony electrode of the present invention with those of a conventional glass electrode in the same solutions, demonstrating the ability of the present invention to accurately measure pi over a broad range;
Fig. 4 is a graph comparing pi readings of antimony electrodes of the present invention maintained in the same solutions with a conventional glass electrode demonstrating the reliability of the antimony electrode over a period of several days; and Fig. 5 is a graph comparing the antimony electrode of the present invention with a copper/antimony electrode in the same solution over time.
Detailed Description Referring now to the drawings:
Earlier electrodes appropriate for sensing hydrogen ion concentration have generally involved a solid electron chemically active redo system to produce a stable electrode potential. Such a redo system has typically been a mercury and mercury chloride (calmly), or silver and silver chloride.
The electrode of the present invention does not require such internal redo system, and in fact, employs only a section of an untreated graphite that is in contact and forms an electrically conductive junction with a sensor of antimony Sub functioning as an internal reference for the electrode.
The basic electrode of the present invention is illustrated in Figs. 1 and 2 as consisting of a bundle of untreated graphite threads that are wrapped around or otherwise connected to a cylindrical section of piece of antimony/antimony oxide. The antimony/graphite junction that forms the internal reference for the electrode is then covered by shrink fitting a plastic sheath thereto that can then be sealed as with an epoxy arranged between the antimony end edge -pa-~23~
and sheath wall to seal out moisture while leaving the antimony face exposed. Soarranged, the antimony/antimonv oxide section will function as the sensing element, the graphite at the graphite/antimony junction acting as the internal reference system with the untreated graphite above this junction functioning as a flexibleelectrical conductor.
The preferred untreated graphite and antimony/antimony oxide used in the construction of the electrode are inexpensive. The antimony used to manufacture the antimony/antimony oxide sensor need only be technical grade, which costs about a penny per electrode, and the preferred graphite will cost about two cents per foot. In practice a graphite manufactured by Hercules Corporation's known as Magnamite h&s be found to work satisfactorily and consists of a thin flexible bundle of graphite fibers, the bundle containing approximately one thousand individual thin graphite fibers maintained together. The small diameter of the bundle facilitates its insertion, with minimal discomfort or harm, through a patient's throat and into their stomach. The graphite fibers in each bundle are small; (approximately seven microns 7 x 10 6 meters) in diameter and when wrapped together form as the bundle a small thread of graphite that has a tensile strength of about 400,000 pounds per square inch. This is approximately twenty times the tensile strength of a copper wire of the same diameter. The electrode has a longstorage life and can be taken off the shelf and used immediately without conditioning, special treatment or preparation. In addition, calibration of the electrode is generally unnecessary as all electrodes that are of similar construction, will provide a measure of pi accurate to within + 0.5 pi units which is more than sufficient accuracy for intragastric measurements.
A preferred method of electrode construction involves drawing molten antimony/antirmony oxide into a thin glass capillary tube of a diameter of approximately 1.7 x lo mm., and allowing it to slowly cool until solid. The glass capillary is then broken away from the brittle antimony oxide rod, which itself can then be easily broken into smaller pieces to make individual electrodes. Such slow cooling of the molten antimony will promote large crystal growth which enhances the stability of the pi electrode, as set out in G. Ed wall, "Influence of Crystallographic Properties on Antimony Electrode Potential I. Polycrystalline Material," Electrochim. Act 24, 595-603,1979.
Fig. l shows a side elevation sectional view of a first embodiment of an antimony and graphite hydrogen ion electrode lo of the present invention hereinafter referred to as electrode lo Electrode lo is preferably constructed by 1232(~16 tightly wrapping a "bundle" of untreated graphite threads 11 around a section, "shot"
or rod of antimony/antimony oxide 12 that is untreated and is covered with impermeable plastic sheath 13 such as one formed from a polyvinyl chloride (PVC)plastic that can be heat shrunk thereto, so as to leave exposed an 5 antimony/antimony oxide tip end 14.
In Fig. 2 is shown a side elevation sectional view of an alternate or second embodiment of the antimony undo graphite hydrogen ion electrode 20 of thepresent invention, hereinafter referred to as electrode 20. Electrode 20 also incorporates untreated graphite threads 21 but involves dipping or otherwise coating 10 an end thereof with a molten mixture of antimony/antimony oxide 22, which coating and the threads above the coating are then covered with an impermeable plastic sheath 23 that is also preferably polyvinyl chloride (PVC) so as to leave exposed an antimony/antimony oxide tip end 24. The electrodes 10 and 20 are each capable ofaccurately measuring hydrogen ion concentrations or pi of aqueous solutions. In 15 each electrode the graphite at the junction with the antimony/antimony oxide sensor functions as an internal reference, with the graphite there above functioning as a conductor. Therefore, it should be understood that that portion of the graphite that functions as a conductor could be replaced with another electrically conductive material such as a copper wire, or the like, within the scope of this disclosure.
20 Either electrode 10 or 20, when connected between a patient's body, that functions as an external reference electrode, and a potentiometer or like voltage measuring device, will continue to provide an accurate measurement of solution pi over a period of a number of days as will be discussed hereinafter with respect to Figs. 3 through 5, allowing the electrode to remain within a patient's stomach over the 25 period of an average patient hospital stay, which period, in practice, is three to four days.
Both the electrode 10 and 20 of Figs. 1 and 2 preferably include encasing the electrode in a sheath of an impermeable plastic tubing 13 and 23 tocover the graphite/antimony junction so as to leave the antimony/antimony oxide tip 30 end 14 or 24 exposed, and each electrode preferably includes an epoxy seal, shown at 15 in Fig. 1 and 25 in Fig. 2, that is coated around the junction of the sheath with the antimony tip edge to provide a moisture tight barrier or seal between the plastic sheath and that antimony/antimony oxide electrode tip. So arranged, each antimony/antimony oxide tip end 14 or 24 will be exposed to allow it to directly35 contact a solution whose pi is to be measured. The electrodes 10 and 20 are preferably encased by plastic sheath 13 and 23 over their length, with ends 16 and 26 1232(~16 thereof, respectively, of each connected to a conductive wire 17 of 27, or the like, that is, in turn, connected to a potentiometer, or like voltage potential measuring device, not shown.
A preferred method of constructing the electrode lo of Fig. l, involves drawing molten antimony/antimony oxide heated to a molten state into a thin glass capillary tube, a preferred tube measuring approximately 1.7 x l00 mm., and allowing that mixture to slowly cool until solid. Antimony segments or rods are then obtained by breaking the glass tubes from there around. The metal rods are then themselves broken into individual cyc1indrical sections or "shots" and are in turn, connected to the graphite fibers by wrapping the fibers tightly around the rod section so as to form the graphite-antimony/antimony oxide interface. The preferred graphite is the Hercules Magnamite~ identified above, that is formed as a thread or bundle from approximately one thousand (1,000) graphite fibers, each fiber being approximately seven microns (7 x lo 6 meters) in diameter. Preferably, a bundle of 1000 of these graphite fibers is used for each electrode. After the antimony/antimony oxide tip is secured thereto, the bundle is covered with a tubular section of polyvinyl chloride (PVC) heat-shrink plastic tubing that is heated to shrink to the bundle, forming an electrical insulator there over, while leaving an antimony/antimony oxide tip end surface uncovered. Thereafter, an epoxy is preferably applied between the exposed antimony/antimony oxide tip end edges junction with the tubing inner circumference forming a moisture proof seal. The opposite end of the electrode is then ready for connection to a conductive lead that, in turn, is connected to a potentiometer, or like electrical potential measuringdevice. The potentiometer is, also connected by a separate line, such as a standard electrocardiogram ERG lead, to the patient's skin, the patient functioning in the loop as an external reference electrode. Such ERG Reads are specially designed for minimal patient discomfort, are relatively inexpensive and are disposable. The electrode so formed has been found in practice to work without preconditioning, to provide an accurate measure of the presence of hydrogen ions in solution.
Another preferred construction procedure used to produce the electrode 20, includes a utilization of elemental powdered antimony that is obtained in bulk. This powdered antimony, as in the fabrication of the electrode lo of Fig. l, is heated to melting in a ceramic beaker to approximately 700 Celsius, and that temperature is maintained, (the melting temperature of antimony is 630.7~ Celsius) thus forming a mixture of antimony (Sub) and antimony oxide (SbO3).
The presence of antimony oxide (SbO3) is necessary to provide an effective sensor ~Z32(~
tip for accurately sensing hydrogen ion concentration and passing that sensed concentration, as a voltage potential, across the internal reference junction of the sensor tip into the contacting graphite. After melting, the antimony/antimony oxide mixture is used to construct the electrode of Fig. 2, by dipping the untreated graphite bundle end directly into the molten antimony/antimony oxide, removing that end therefrom, and allowing the antimony/antimony oxide that remains thereon to cool and harden. Usually one dipping of the bundle of fibers in the molten antimony/antimony oxide mixture will provide a sufficient coating that, when it is allowed to cool and solidify, will produce a very thin layer of antimony/antimony oxide bonded to the graphite fibers. Thereafter the bundle is encased within theplastic tubing 23, leaving an antimony/antimony oxide end 24 surface exposed, and any space between the edge of that end and the plastic tubing inner circumference is sealed at 25 by application of an epoxy, or the like, thereto.
The graphite/antimony interface of electrode 20 like that of electrode 10, will function as an internal reference, passing an electrode potential to a voltage measuring device that remains consistent over a significant time period. The antimony electrode potential can be referred to as a corrosion potential, and, although it is not thoroughly understood, it is believed to be mainly governed by the following two equations as set out in, M. Markdahl~Bjarme and G. Ed wall, "Modified Conventional Type of pCO2-Electrode With Monocrystalline Antimony as the pH-sensing Element", Med. Blot. Erg. Compute 19, 447-456,1981.
2Sb + 3H20~Sb203 + OH + ye and 0 + OH+ + 4 - ` OH 0 That the graphite/antimony electrode will perform as a pi electrode is demonstrated in Fig. 3. Therein, the open circles (o) show the change in potential (my) of a graphite/antimony electrode as compared with a change irk potential 30 measured by a conventional glass pi electrode in the same solution identified as closed circles (o).
In it 4 the long-term stability of two separate graphite/antimony electrodes is compared with that of a standard gloss pi electrode. The graph shows that, over a period of two and one-half days, the apparent pi of the graphite-35 antimony electrodes was identical and only a difference of 0.2 pi unit was seen -lo-~23Z(~ 6 after four and one half days, with the glass pi electrode shown to have drifted about 0.1 pi unit over that four and one-half day period.
Fig. 5 Chavez vertical lines bisecting open (o) and closed (~) circles that indicate, respectively, copper/antimony and graphite/antimony electrodes, the 5 length of the vertical lines indicating the variance in pi values obtained from three individual antimony/graphite electrodes as compared to equivalent data from electrodes with antimony/copper junctions, utilizing a ply 2 solution. The data was obtained over 150 hours of recording. The bars represent the standard deviation,with a range of acceptable error for gastric analysis, of + 0.5 pi unit. From an10 inspection of Fig. 5, the antimony/graphite electrodes showed a small drift of about -0.25 pi unit for the initial 10 hours, with an apparent change of only .05 pi unit during the period from 25-150 hours, that is well within the range of acceptableerror. Whereas, the copper/antimony electrodes are shown to have drifted appreciably at the 10 hour point and continued to drift badly thereafter. It i 15 obvious from Fig. 5 that the standard deviation of readings from the antimony/graphite electrode of any single data point is very "tight" compared to the readings from the copper/antimony electrodes. In practice, and as has been set out in the earlier cited patent by NAGOYA. Ed wall, and US Eklund, "Monocrystalline little Electrode and Method of Use", US. Patent No. 4,119,498; 1978, the 20 characteristics of low drift and small standard deviation can be further enhanced by a slower cooling of the antimony in a practice of fabricating the electrode of the present invention.
While hereinabove have been detailed preferred embodiments of antimony/antimony electrodes and a process for their manufacture, it should be 25 understood that the electrode of the invention can be formed by processes different from those described and that other configurations or arrangements of untreated graphite and even different types of untreated graphite can be used from those set out herein within the scope of this disclosure so long as the graphite/antimony junction is "tight" to produce the required internal reference junction. It should, 30 therefore, be understood that the present disclosure is made by way of example only and that changes in the electrode construction from the preferred embodiments and in the outlined processes of manufacture, can be made without departing from thesubject matter conning within the scope of the following claims, which claims weregard as our invention.
Claims
THE CLAIMS
1. An electrode for use in measuring hydrogen ion concentration comprising a graphite core; an antimony/antimony oxide sensor secured in electrical contact with said graphite core and having an exposed surface for immersion in atest solution; and means for electrically isolating said graphite core and antimony/antimony oxide sensor junction from said test solution when said antimony/antimony oxide exposed surface is immersed therein.
2. An electrode according to Claim 1, wherein the means for electrically isolating said graphite core consists of an impermeable plastic coating arranged over said graphite core and over said antimony/antimony oxide sensor junction to said graphite core, so as to leave a surface of said sensor exposed.3. An electrode according to Claim 2, wherein the impermeable plastic coating is a tubular plastic sheath that is fitted over and shrunk to closely fit against the graphite core and graphite and antimony/antimony oxide sensor junction.
4. An electrode according to Claim 3, wherein the impermeable plastic sheath is heat-shrink polyvinylchoride (PVC) plastic.
5. An electrode according to Claim 2 further including an epoxy seal arranged as a moisture proof seal between the tubular plastic sheath inner circumference and the edge of the antimony/antimony oxide exposed surface.
6. An electrode according to Claim 1, wherein the untreated graphite core is a bundle of flexible graphite fibers maintained together.
7. An electrode according to Claim 6, wherein the antimony/antimony oxide sensor surface is formed by dipping the end of the bundle of graphite fibers into molten antimony/antimony oxide to coat tile fibers with that antimony/antimony oxide and allowing that coating to dry thereto.
8. An electrode according to Claim 1, wherein the antimony/antimony sensor consists of, a solid section of antimony/antimony oxide that receives thegraphite core wrapped therearound forming an electrical junction where said section of antimony/antimony oxide is contacted by said graphite core.
9. An electrode according to Claim 1, wherein the mix of antimony and antimony oxide is obtained by heating elemental powdered antimony to approximately 700° Celsius.
10. An electrode for use in measuring hydrogen ion concentration comprising an antimony/antimony oxide sensor; a section of graphite maintained in electrical contact to said antimony/antimony oxide sensor functioning as an internal reference; electrically conductive means connected to said section of graphite for passing an electrical potential therefrom; and means for electrically isolating said section of graphite and connected electrically conductive means from a test solution to leave exposed a portion of said antimony/antimony oxide sensor to said test solution.
11. An electrode according to Claim 10, wherein the means for electrically isolating said section of graphite and electrically conductive means consists of an impermeable plastic coating arranged over said section of graphite, the electrically conductive means and over said antimony/antimony oxide sensor junction to said section of graphite, so as to leave a surface of said sensor exposed.
12. An electrode according to Claim 11, wherein the impermeable plastic coating is a tubular plastic sheath that is fitted over and shrunk to closely fit there against.
13. An electrode according to Claim 12, wherein the impermeable plastic sheath is heat-shrink polyvinylchloride (PVC) plastic.
14. An electrode according to Claim 11, further including an epoxy seal arranged as a moisture proof seal between the tubular plastic sheath inner circumference and the edge of the antimony/antimony oxide exposed surface.
15. An electrode according to Claim 10, wherein the section of graphite and the electrically conductive means is a bundle of flexible graphite fibers maintained together.
16. An electrode according to Claim 15, wherein the section of graphite junction with the antimony/antimony oxide sensor surface is formed by dipping the end of the bundle of graphite fibers into molten antimony/antimony oxide to coat the fibers with that antimony/antimony oxide and allowing that coating to dry thereto.
17. An electrode according to Claim 15, wherein the section of graphite junction with the antimony/antimony oxide sensor is formed by wrapping the bundle of graphite fibers around a solid section of antimony/antimony oxide so as to form an electrical junction, while leaving an antimony/antimony oxide surface exposed.
18. An electrode according to Claim 10, wherein the mix of antimony and antimony oxide is obtained by heating elemental powdered antimony to approximately 700° Celsius.
19. A proccess for manufacturing an antimony and graphite hydrogen ion electrode comprising the steps of, connecting a section of graphite to an antimony/antimony oxide sensor so as to provide an internal reference junction;
connecting that section of graphite to an electrical conductor; encasing said graphite and antimony/antimony oxide sensor junction and the electrical conductor in a liquid impervious sheath so as to leave a portion of said sensor exposed; and connecting said electrical conductor to an electrically conductive lead.
20. A process of manufacture as recited in Claim 19, wherein the section of graphite and the electrical conductor is a bundle of graphite fibers consisting of approximately one thousand fibers each of an average diameter of seven (7) microns.
21. A process of manufacture as recited in Claim 19, further including the step of applying an epoxy as a liquid tight seal between the sheath and the adjacent antimony/antimony oxide sensor edge providing a liquid tight seal around the junction of the antimony/antimony oxide and section of graphite.
22. A process of manufacture as recited in Claim 19, wherein the antimony/antimony oxide sensor is formed by drawing a column of a molten mix of antimony/antimony oxide into a breakable tube; allowing said mix to cool; breaking said tube away therefrom and breaking the solidified column into sections or "shots";
and wrapping the graphite bundle there around to form the internal reference junction therebetween.
23. A process of manufacture as recited in Claim 22, wherein the molten antimony/antimony oxide mix is allowed to cool in atmosphere.
24. A process of manufacture as recited in Claim 19, wherein the antimony/antimony oxide sensor is formed by dipping an end of the untreated graphite bundle into a molten mix of antimony/antimony oxide; withdrawing that dipped end; and allowing the antimony/antimony oxide mix to dry and solidify thereon.
25. A process of manufacture as recited in Claim 19, further including the step of connecting an electrically conductive lead to the graphite above the graphite-antimony/antimony oxide junction.
1. An electrode for use in measuring hydrogen ion concentration comprising a graphite core; an antimony/antimony oxide sensor secured in electrical contact with said graphite core and having an exposed surface for immersion in atest solution; and means for electrically isolating said graphite core and antimony/antimony oxide sensor junction from said test solution when said antimony/antimony oxide exposed surface is immersed therein.
2. An electrode according to Claim 1, wherein the means for electrically isolating said graphite core consists of an impermeable plastic coating arranged over said graphite core and over said antimony/antimony oxide sensor junction to said graphite core, so as to leave a surface of said sensor exposed.3. An electrode according to Claim 2, wherein the impermeable plastic coating is a tubular plastic sheath that is fitted over and shrunk to closely fit against the graphite core and graphite and antimony/antimony oxide sensor junction.
4. An electrode according to Claim 3, wherein the impermeable plastic sheath is heat-shrink polyvinylchoride (PVC) plastic.
5. An electrode according to Claim 2 further including an epoxy seal arranged as a moisture proof seal between the tubular plastic sheath inner circumference and the edge of the antimony/antimony oxide exposed surface.
6. An electrode according to Claim 1, wherein the untreated graphite core is a bundle of flexible graphite fibers maintained together.
7. An electrode according to Claim 6, wherein the antimony/antimony oxide sensor surface is formed by dipping the end of the bundle of graphite fibers into molten antimony/antimony oxide to coat tile fibers with that antimony/antimony oxide and allowing that coating to dry thereto.
8. An electrode according to Claim 1, wherein the antimony/antimony sensor consists of, a solid section of antimony/antimony oxide that receives thegraphite core wrapped therearound forming an electrical junction where said section of antimony/antimony oxide is contacted by said graphite core.
9. An electrode according to Claim 1, wherein the mix of antimony and antimony oxide is obtained by heating elemental powdered antimony to approximately 700° Celsius.
10. An electrode for use in measuring hydrogen ion concentration comprising an antimony/antimony oxide sensor; a section of graphite maintained in electrical contact to said antimony/antimony oxide sensor functioning as an internal reference; electrically conductive means connected to said section of graphite for passing an electrical potential therefrom; and means for electrically isolating said section of graphite and connected electrically conductive means from a test solution to leave exposed a portion of said antimony/antimony oxide sensor to said test solution.
11. An electrode according to Claim 10, wherein the means for electrically isolating said section of graphite and electrically conductive means consists of an impermeable plastic coating arranged over said section of graphite, the electrically conductive means and over said antimony/antimony oxide sensor junction to said section of graphite, so as to leave a surface of said sensor exposed.
12. An electrode according to Claim 11, wherein the impermeable plastic coating is a tubular plastic sheath that is fitted over and shrunk to closely fit there against.
13. An electrode according to Claim 12, wherein the impermeable plastic sheath is heat-shrink polyvinylchloride (PVC) plastic.
14. An electrode according to Claim 11, further including an epoxy seal arranged as a moisture proof seal between the tubular plastic sheath inner circumference and the edge of the antimony/antimony oxide exposed surface.
15. An electrode according to Claim 10, wherein the section of graphite and the electrically conductive means is a bundle of flexible graphite fibers maintained together.
16. An electrode according to Claim 15, wherein the section of graphite junction with the antimony/antimony oxide sensor surface is formed by dipping the end of the bundle of graphite fibers into molten antimony/antimony oxide to coat the fibers with that antimony/antimony oxide and allowing that coating to dry thereto.
17. An electrode according to Claim 15, wherein the section of graphite junction with the antimony/antimony oxide sensor is formed by wrapping the bundle of graphite fibers around a solid section of antimony/antimony oxide so as to form an electrical junction, while leaving an antimony/antimony oxide surface exposed.
18. An electrode according to Claim 10, wherein the mix of antimony and antimony oxide is obtained by heating elemental powdered antimony to approximately 700° Celsius.
19. A proccess for manufacturing an antimony and graphite hydrogen ion electrode comprising the steps of, connecting a section of graphite to an antimony/antimony oxide sensor so as to provide an internal reference junction;
connecting that section of graphite to an electrical conductor; encasing said graphite and antimony/antimony oxide sensor junction and the electrical conductor in a liquid impervious sheath so as to leave a portion of said sensor exposed; and connecting said electrical conductor to an electrically conductive lead.
20. A process of manufacture as recited in Claim 19, wherein the section of graphite and the electrical conductor is a bundle of graphite fibers consisting of approximately one thousand fibers each of an average diameter of seven (7) microns.
21. A process of manufacture as recited in Claim 19, further including the step of applying an epoxy as a liquid tight seal between the sheath and the adjacent antimony/antimony oxide sensor edge providing a liquid tight seal around the junction of the antimony/antimony oxide and section of graphite.
22. A process of manufacture as recited in Claim 19, wherein the antimony/antimony oxide sensor is formed by drawing a column of a molten mix of antimony/antimony oxide into a breakable tube; allowing said mix to cool; breaking said tube away therefrom and breaking the solidified column into sections or "shots";
and wrapping the graphite bundle there around to form the internal reference junction therebetween.
23. A process of manufacture as recited in Claim 22, wherein the molten antimony/antimony oxide mix is allowed to cool in atmosphere.
24. A process of manufacture as recited in Claim 19, wherein the antimony/antimony oxide sensor is formed by dipping an end of the untreated graphite bundle into a molten mix of antimony/antimony oxide; withdrawing that dipped end; and allowing the antimony/antimony oxide mix to dry and solidify thereon.
25. A process of manufacture as recited in Claim 19, further including the step of connecting an electrically conductive lead to the graphite above the graphite-antimony/antimony oxide junction.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US635,755 | 1984-07-30 | ||
| US06/635,755 US4561963A (en) | 1984-07-30 | 1984-07-30 | Antimony and graphite hydrogen ion electrode and method of making such electrode |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1232016A true CA1232016A (en) | 1988-01-26 |
Family
ID=24548989
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000487702A Expired CA1232016A (en) | 1984-07-30 | 1985-07-29 | Antimony and graphite hydrogen ion electrode |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4561963A (en) |
| EP (1) | EP0171959B1 (en) |
| JP (1) | JPS6141443A (en) |
| AT (1) | ATE51303T1 (en) |
| CA (1) | CA1232016A (en) |
| DE (1) | DE3576731D1 (en) |
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| GB8428543D0 (en) * | 1984-11-12 | 1984-12-19 | Settler B | Antimony electrode assembly |
| GB2182446A (en) * | 1985-11-08 | 1987-05-13 | Bert Settler | Antimony electrode assembly |
| EP0266432B1 (en) * | 1986-04-22 | 1992-01-15 | Toray Industries, Inc. | Microelectrode for electrochemical analysis |
| EP0283962A3 (en) * | 1987-03-19 | 1989-11-15 | Dentsply Management Corp. | Method for measuring periodontal pocket gases |
| US4798655A (en) * | 1987-03-19 | 1989-01-17 | Howard Diamond | Multiparameter analytical electrode structure and method of measurement |
| US4952300A (en) * | 1987-03-19 | 1990-08-28 | Howard Diamond | Multiparameter analytical electrode structure and method of measurement |
| US4929426A (en) * | 1987-11-02 | 1990-05-29 | Biologix, Inc. | Portable blood chemistry measuring apparatus |
| AU2713588A (en) * | 1987-11-02 | 1989-06-01 | Biologix Inc. | Electrode system for use in a portable blood chemistry measuring apparatus |
| US4940945A (en) * | 1987-11-02 | 1990-07-10 | Biologix Inc. | Interface circuit for use in a portable blood chemistry measuring apparatus |
| DE3816458A1 (en) * | 1988-05-13 | 1989-12-21 | Josowicz Mira | ULTRAMICROELECTRODE, METHOD FOR THE PRODUCTION THEREOF AND THEIR USE |
| US5284705A (en) * | 1990-09-06 | 1994-02-08 | Garland Floor Co. | Antistatic coating comprising tin-oxide-rich pigments and process and coated substrate |
| DE4314007C2 (en) * | 1993-04-26 | 1999-05-27 | Elbau Elektronik Bauelemente G | Measuring electrode arrangement |
| US7885697B2 (en) | 2004-07-13 | 2011-02-08 | Dexcom, Inc. | Transcutaneous analyte sensor |
| US6097984A (en) * | 1998-11-25 | 2000-08-01 | Medtronic, Inc. | System and method of stimulation for treating gastro-esophageal reflux disease |
| AUPQ015299A0 (en) * | 1999-05-04 | 1999-05-27 | University Of South Australia | Ph probe |
| GB2373053A (en) * | 2001-03-01 | 2002-09-11 | Univ Oxford Brookes | Measuring electrode, particularly pH sensing electrode |
| US6965791B1 (en) * | 2003-03-26 | 2005-11-15 | Sorenson Medical, Inc. | Implantable biosensor system, apparatus and method |
| US7182847B1 (en) | 2003-05-07 | 2007-02-27 | Millar Instruments | System and probe for monitoring pH levels of a sample medium |
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| US8423114B2 (en) | 2006-10-04 | 2013-04-16 | Dexcom, Inc. | Dual electrode system for a continuous analyte sensor |
| US8287453B2 (en) | 2003-12-05 | 2012-10-16 | Dexcom, Inc. | Analyte sensor |
| US8774886B2 (en) | 2006-10-04 | 2014-07-08 | Dexcom, Inc. | Analyte sensor |
| US20100185071A1 (en) * | 2003-12-05 | 2010-07-22 | Dexcom, Inc. | Dual electrode system for a continuous analyte sensor |
| US11633133B2 (en) | 2003-12-05 | 2023-04-25 | Dexcom, Inc. | Dual electrode system for a continuous analyte sensor |
| EP2239566B1 (en) | 2003-12-05 | 2014-04-23 | DexCom, Inc. | Calibration techniques for a continuous analyte sensor |
| CN100422728C (en) * | 2006-03-28 | 2008-10-01 | 浙江大学 | Metal antimony oxide electrode and method for tracking and detecting medium pH change |
| US8924159B2 (en) | 2008-05-30 | 2014-12-30 | Abbott Diabetes Care Inc. | Method and apparatus for providing glycemic control |
| US9801575B2 (en) | 2011-04-15 | 2017-10-31 | Dexcom, Inc. | Advanced analyte sensor calibration and error detection |
| CN102565164B (en) * | 2012-02-01 | 2014-03-12 | 江苏大学 | Method for producing antimony pH electrode modified by two layers of films |
| PL2689903T3 (en) | 2012-07-23 | 2018-05-30 | Scm Group Tecmatic Maquinas E Equipamentos Ltda | Rounding and trimming group for edges of panels |
| DE102019110920A1 (en) * | 2019-04-26 | 2020-10-29 | Jumo Gmbh & Co. Kg | Measuring electrode for electrochemical measurements and method for producing a measuring electrode |
| DE102019110919A1 (en) * | 2019-04-26 | 2020-10-29 | Jumo Gmbh & Co. Kg | Measuring electrode for electrochemical measurements and method for producing a measuring electrode |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US2168867A (en) * | 1937-08-05 | 1939-08-08 | Takamine Ferment Company | Method and apparatus for testing the contents of the stomach and other body cavities |
| US2288180A (en) * | 1938-06-08 | 1942-06-30 | Beatrice Creamery Company | Apparatus for measuring ph |
| FR1010967A (en) * | 1948-11-13 | 1952-06-17 | Pour L Applic Des Procedes Bio | electrode intended for pH measurement, its manufacturing process and its applications |
| US3742594A (en) * | 1971-05-10 | 1973-07-03 | Harco Electr Ltd | Antimony electrodes and method of manufacturing same |
| US3926764A (en) * | 1971-05-19 | 1975-12-16 | Radiometer As | Electrode for potentiometric measurements |
| GB1542859A (en) * | 1975-12-18 | 1979-03-28 | Nat Res Dev | Electrode assemblies |
| SE409372B (en) * | 1976-07-13 | 1979-08-13 | Edwall Gunnar | ELECTRODE FOR DETERMINATION OF PH MM IN VETSKOR |
| US4221567A (en) * | 1977-12-23 | 1980-09-09 | Intermountain Health Care | Sampling and determination of diffusible chemical substances |
| US4338175A (en) * | 1979-03-21 | 1982-07-06 | Mcnab, Incorporated | All solid state electrode system |
| ZA803141B (en) * | 1979-06-07 | 1981-08-26 | Medishield Corp Ltd | Apparatus for analysis of absorbed gases |
| US4431508A (en) * | 1982-12-10 | 1984-02-14 | Brown Jr Harold M | Solid state graphite electrode |
| DE3333660A1 (en) * | 1983-09-17 | 1985-04-11 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., 8000 München | Electrode for electrochemical methods of measurement |
-
1984
- 1984-07-30 US US06/635,755 patent/US4561963A/en not_active Expired - Lifetime
-
1985
- 1985-07-26 EP EP85305342A patent/EP0171959B1/en not_active Expired - Lifetime
- 1985-07-26 AT AT85305342T patent/ATE51303T1/en not_active IP Right Cessation
- 1985-07-26 DE DE8585305342T patent/DE3576731D1/en not_active Expired - Fee Related
- 1985-07-29 CA CA000487702A patent/CA1232016A/en not_active Expired
- 1985-07-29 JP JP16846585A patent/JPS6141443A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0171959A2 (en) | 1986-02-19 |
| EP0171959A3 (en) | 1987-02-04 |
| ATE51303T1 (en) | 1990-04-15 |
| US4561963A (en) | 1985-12-31 |
| DE3576731D1 (en) | 1990-04-26 |
| JPS6141443A (en) | 1986-02-27 |
| EP0171959B1 (en) | 1990-03-21 |
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