DE2706942A1 - COMBINATION ELECTRODE - Google Patents

Description

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ZTISTKLtUNGSANSCUKIFT: 2OOO ΠΑΜΒϋΙΙΟ 30 · NKUKH WALL · 41 PLKASK KKIM. Y TO:

'TELEPHONE (010) 30 7128 and 36 4113

TELKOR. NEOEDAPATENT ITAMBURO

Owens-Illinois, Inc. · 3 · sooo münchkn 2 · mozartstr. 23

TELEPHONE (Ο89) 3 38 03 SUN
P. 0. BOX IO35 TKLBOR. NEOKDAPATENT MfHCElII

Toledo, Ohio kj 666 / USA Hamburg, February 14, 1977 Combination electrode

The invention relates to a combination electrode that has a
ion-sensitive glass electrode and a reference electrode.

Ion-sensitive glass electrodes for measuring the concentration of hydrogen (ie pH), sodium ions, ammonium ions, potassium ions and other ions in aqueous solutions have been known for many years. For example, US Pat. No. 2,829,090 describes an electrode made from a glass which
is selectively sensitive to sodium ions. A glass electrode for potassium ions is described in US 3 O41 2 $ 2 and pH-sensitive glasses are described in US Patents 3 8θ6 440,
3,649,505 and 2,756,203. The monograph "Electrometric pH Determinations" by Roger G. Bates
(John Wiley & Sons, Inc., New York). Of the
The term "ion-sensitive glass membrane" is used here in conjunction

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Mood with its use in the technology of potentiometric Electrodes is used and is intended to include a glass electrode tip having a pair of surfaces between the charge transfer takes place.

In the past, glass electrodes were made by blowing a thin membrane of ion-sensitive glass to the end of a tube made of chemically resistant glass tubing or by gluing such an ion-sensitive glass membrane to the end of the glass tubes (e.g. by direct fusing or with adhesives). Recently they have become planar or flat ion-sensitive glass membranes as described in commonly assigned US Pat. No. 3,806 kkO "These electrodes are used in conjunction with reference electrodes such as silver-silver chloride electrodes or calomel electrodes"

With the advancement of medical and industrial technology, a need arose for combination electrodes, which contain both the ion-sensitive glass membrane and the reference electrode, so that a single electrode unit can be used to carry out the measurement This is almost a necessity in industrial and medical applications, where using two electrodes for microsampling is quite a nuisance.

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Such combination electrodes were found in the past necessarily inconvenient geometric shapes because of the glass forming processes involved in making such Electrodes used were subject to restrictions. With such earlier combination electrodes, e.g. according to U.S. Patents 3,880,737 and 3,399,667 was the reference electrode placed in different places on the body of the combination electrode, so that it was always necessary to have a substantial Proportion of the correlation electrode body in the test sample to immerse. Other combination electrodes are available on the market that use an onion-shaped glass membrane use with a reference electrode attached to the side of the electrode body. This immersion is often needed a depth of the test solution of 2.5 cm or more to make the measurement. Therefore, the combination electrode could only be used in applications where a substantial volume of test solution was present could not be used to measure ion concentrations in small samples where only a thin film of the Sample was available.

The present invention avoids the disadvantages of the prior art and provides a combination electrode of Unique structure and geometry are available that cover at least part of the liquid-permeable porous pin the reference electrode for porous connection with inhibited passage

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flowed and the ion-sensitive membrane in a coplanar juxtaposition for convenient contact with small sample volumes and applications in thin films

The subject of the invention is therefore a combination electrode, which contains an ion-sensitive glass electrode and a reference electrode and is characterized in that it is a tube Shaped housing containing the glass electrode, the glass electrode being a substantially planar, ion-sensitive Contains glass membrane in a position for contact with a test sample, the membrane being sealed with a tube made of chemically Resistant glass is connected and so an inner electrode cavity , which contains an internal electrolyte solution, forms a first reference element which is contained in this cavity in Contact with the electrolyte solution is attached and used for electrical Connection to an electrometer is set up, and a reference electrode with porous connection and inhibited Contains flux which has a liquid permeable porous pin which is in a position for contact with of the sample, with at least a portion of the surface of the pin coplanar with the glass membrane, the Pen in connection with a reservoir for a reference electrolyte solution and a second reference element in the reservoir is in electrical connection with the reference electrolyte and for electrical connection with the

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Elektx'oineter is set up.

f. wisely, the porous pin has a substantially planar shape Surface coplanar with the glass membrane j However, a pen with a rounded one can also be used for this purpose or curved surface can be used

Other purposes, features and advantages of the present invention will become readily apparent from the following description with the figures evident.

Fig. 1 is a cross section through the combination electrode according to the invention;

Figure 2 is a partial perspective view of the end

of the electrode according to the invention, the coplanar arrangement of the reference electrode and the glass membrane clarified; and

Fig. 3 is a perspective view of the electrode unit shown in Fig. 1.

In the figures, 10 generally denotes the combination electrode, which is a rigid, tubular, electrical insulating housing 11 made of plastic, glass or another has suitable material. The lower end of the housing 11

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contains an elastic plug 12 made of silicone rubber or similar material. Plug 12 has two openings 12a and 12b provided

In the opening 12a a glass electrode is sealingly attached, which contains an inert, chemically resistant glass tube 13, at the lower end of which a planar ion-sensitive glass membrane "\ k in the form of a flat disk is tightly attached. The lower end of the glass tube 13 is closed by the elastic Plug

the

12 comprises sealingly and held in position so that / lower

The end of the ion-sensitive glass membrane 1k is "flat" or coplanar with the lower end of the plug 12 11 seated

The glass tube 13 contains a storage container with aqueous buffered internal electrolyte solution Λ6 (eg 0.2 M KCl) which is customary and known to the person skilled in the art. Inside the glass tube

13 is a first reference element 17 in the form of a silver wire attached · The lower end of the reference element 17 is attached to a provided thin silver chloride coating 17a and this Coating dips into the electrolyte 16

Reference element 17 is positioned within tube 13 by apertured support 18 and O-ring 19 held · The O-ring 19 is used to seal the

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Electrolyte 16 in the lower end of the tube 13 and earlier « changes its leakage into the upper part of the electrode, the upper end of the reference element 17 is electrically insulated with a electrical cable 20 connected, which is provided with an electrical connector 21 for connection to an electrometer »

The inside of the glass tube 13 above the bracket 18 and below-one half of the cap ^ O is covered with a non-conductive plastic / bedding material 4i, such as an epoxy resin, for electrical To produce insulation «

A liquid-permeable, porous plastic pin 30 made of porous polyethylene with a volume porosity of 30 $ and an average pore diameter of about 20 microns is sealed in the opening 12b in the elastic plug 12. The porous post has a substantially planar surface 30a that is coplanar with the lower end of the glass membrane 1h. Pen 30 is available from Porex Materials Corporation, Div. Glasrock Products, 7380 Bohannon Road, Fairburn, Georgia under the trademark Porex The porous stick 30 is made of porous ceramic, porous glass, sintered glass frit, porous plastic (such as is used for mushroom sticks), absorbent mat or wick, or any Another common liquid permeable material used to create porous connection and restrained flow reference electrodes, as described in Aids for the Analyst, Volume 3, March 1955, page 1 * 72- ^ 73j

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Kirk-Othmer, Encyclopedia of Chemical Technology, Volume 11, page 385; Roger G. Bates, Determination of pH, Chapter 10, pages 318-320 (John Viley & Sons); and G ₉ Mattock and DM Volume, Interpretation of pH and Cation Measurements, pages 18-25,

The porous pin JO ends above the elastic plug 12 and extends into the annular chamber which is formed between the housing 11 and the glass tube 13. This annular chamber contains a reference electrolyte solution 32,

is a conventional aqueous electrolyte / or, for example, an aqueous solution of kn KCl, improved electrolyte such as an aqueous gel, the Hue KCl and is described in the commonly assigned patent application entitled "Electrode and improved electrolyte""A Second reference element 33 is in the form of a silver wire, which is provided at the lower end with a thin coating of silver chloride 33 *, is immersed in this reference electrolyte solution. Reference element 33 is held at the upper end in the opening 15b of the elastic plug 15. This is a common silver-silver chloride reference electrode and at least the coating 33a must be immersed in the electrolyte solution 32. The porous plug 30, together with the silver-silver chloride electrode 33 and 33a, comprises a reference electrode with a porous connection with an inhibited flow.

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The loading element 33 is electrically connected to an insulated electrical cable 3k which is provided with an electrical connector 35 for connection to an electrometer. The cables 20 and 3k are shown coaxially and are mutually electrically shielded The upper end of the housing is covered with a plastic cap 4o to close and hold the electrode unit

The ion-sensitive is preferably for economic reasons in production and for reasons of flexibility in handling Glass membrane a disk made of pH-sensitive glass, which by means of a suitable adhesive or by fusing, such as, for example, applied tightly to a chemically resistant glass tube by means of a glassblower technique (lampwork techniques) is"

The composition of the ion-sensitive glass membrane or the chemically resistant glass tube are known to those skilled in the art and do not form part of the present invention. Such glass compositions and techniques for preparation are described in commonly assigned U.S. Patent 3,8O6 hkO and in Roger G. Bates, Determination of pH , Chapter 9 "(John Viley * Sons, Inc.), 1974. All patents and publications cited here form part of the present disclosure. In summary, the invention relates to a combination electrode with an ion-sensitive glass membrane and a reference electrode with porous connection and inhibited

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River that has a unique structure and geometry
and for convenient contact with small amounts of sample and for thin film applications, has a substantially planar β glass membrane and at least a portion of the surface of the porous restrained flow connection for the reference electrode in coplanar relationship therewith.

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Claims (1)

Claims t ») Comliination electrode with an ion-sensitive glass electrode and a reference electrode, characterized by a tubular housing (ii) which accommodates the glass electrode, the glass electrode containing a substantially planar ion-sensitive glass membrane (i4) arranged for contact with a test sample, the membrane for forming a inner electrode cavity is sealed with a chemically resistant glass tube (13), and the cavity contains an internal electrolyte solution (16); a first reference element (17) which is mounted in the cavity in contact with the electrolyte solution (16), the reference element (17) being adapted for electrical connection to an electrometer, a reference electrode with porous connection and inhibited flow, which is a liquid-permeable porous Pin (30), wherein at least a portion of the surface of the pin is arranged for contact with the sample and in coplanar relationship with the glass membrane (1 * 0 and the pin is in communication with a reservoir for a reference electrolyte solution (32), and a second reference element (33) which is in electrical connection with the reference electrolyte (32) in the storage container and is set up for electrical connection with the electrometer. 709839/0703 - 12 ORIGINAL INSPECTED 2/06942 • A; · 2 »Combination electrode according to claim. 1, characterized in that that the glass membrane (i4) consists of a pH-sensitive Glass consists 3. Combination electrode according to claim 1, characterized in that that the glass membrane (14) is sensitive to sodium Glass is * 4. Combination electrode according to claim 1, characterized in that that the glass membrane (14) is a potassium-sensitive glass. 5 combination electrode according to one of claims 1 to 4, characterized in that the surface (30a) of the pin (30) is substantially planar 6 «Combination electrode according to one of Claims 1 to 5» characterized in that the porous pin (30) is made of a porous ceramic material ?, " 7 · Combination electrode according to one of Claims 1 to 6, characterized in that the second reference element (33) is a silver / silver chloride electrode " 8. Combination electrode according to one of Claims 1 to 5 or 7, characterized in that the porous pin (30) consists of a porous plastic " 709839/0703