Classifications

• • 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
  • G01N27/283—Means for supporting or introducing electrochemical probes

Definitions

• the invention relates to a measuring electrode arrangement for measuring in liquids, comprising a working, an auxiliary and a reference electrode, each made of metal.
• the most frequently used electrochemical measuring method is potentiometry, which is used not only for analytical purposes, but also for the determination of physico-chemical data. Voltametric methods, in which current-voltage curves are recorded and evaluated, are closely related to this. These methods work with sample solutions into which electrodes are immersed.
• the electrodes are a measuring electrode, which is the actual working electrode, and possibly an auxiliary electrode as a second electrode.
• a further reference electrode is preferably used, which is an electrode with precisely known and reproducible potentials.
• the selection of the electrode materials depends on the sample solutions to be examined and their components. Mercury is a very suitable measuring electrode material. Platinum is also particularly suitable for use as a measuring electrode. Gold and silver are also used. As
• REPLACEMENT LEAF Reference electrodes are electrodes of the second type, most often the calomel electrodes and silver chloride electrodes.
• the electrode designs are selected depending on the respective applications. Normal forms of the electrodes are metal pins and rings, which are usually melted into a glass tube. Polypropylene shafts are used, for example, for measurements in hydrofluoric solutions.
• an electrolyte key i.e. an electrolyte bridge is used to connect the two solutions. It is a suitably shaped tube that e.g. filled with an ammonium nitrate, potassium nitrate, potassium chloride solution and is porous at the ends.
• the invention has for its object to provide a Meßelektro ⁇ the arrangement of the type mentioned, which is inexpensive to manufacture and which allows the use of a small sample volume.
• a measuring electrode arrangement according to the invention for measuring in liquids thus comprises a working, an auxiliary and
• the carrier has a hollow Sta * b, in which the shaft and the rod-shaped conductor of the auxiliary electrode are taken date ⁇ and are embedded in the outer circumference of the pin or wire of the measuring and the reference electrode. This results in a particularly space-saving and easy-to-assemble arrangement.
• the carrier is expediently provided with a sleeve in the front region, as a result of which the electrode arrangement is protected and further insulated with respect to surrounding components.
• the sleeve is advantageously a union nut and can therefore be easily attached and removed.
• the inventive measuring electrode are the reference electrode and 'the measuring electrode in the same solution. There is therefore no need for an electrolyte bridge. By simply switching the measuring and reference electrodes, the latter can be re-chlorinated with the measuring electrode.
• Electrode wires with a diameter of 0.5 mm are usually used.
• a measuring electrode arrangement with a total diameter of 5 mm could be realized.
• a measuring electrode arrangement according to the invention is extremely well suited for use as an amperometric measuring cell in a flow injection analysis system.
• the measuring electrode arrangement is built into a flow measuring chamber, which expediently consists of acrylic glass (plexiglass).
• the invention is further preferred in the following based on
• E SAJZBLATT 3 a reference electrode, each made of metal and installed in a carrier made of plastic material.
• the measuring electrode is preferably a platinum electrode, the auxiliary electrode is a gold electrode and the reference electrode is a silver chloride electrode.
• the carrier is preferably made of polyvinyl chloride (PVC), a very chemical-resistant material.
• PVC polyvinyl chloride
• a particularly expedient electrode arrangement results if the auxiliary electrode is arranged centrally and is pin-shaped or plate-shaped. This enables a symmetrical or corresponding arrangement of the measuring and reference electrodes.
• the shaft of the auxiliary electrode is advantageously connected to a rod-shaped conductor, for example by inserting or screwing it directly into this or into a central attachment.
• the rod-shaped conductor can e.g. be made of copper.
• a very favorable electrode arrangement results if the auxiliary electrode is flush with the end face of the carrier.
• the measuring and reference electrodes each consist of a pin or wire which is bent at the front end. As a result, the electrode area is enlarged.
• the bent end is expediently adapted to the shape of the carrier. For example, it can rest against this side.
• the measuring and reference electrodes are expediently set back with respect to the auxiliary electrode. In this way, undesired interactions and disturbances can be avoided.
• FIG. 1 (a), (b), (c) are perspective views of a carrier, a measuring or reference electrode arrangement and an auxiliary electrode arrangement, according to a first example of the measuring electrode arrangement,
• FIG. 3 (a) and (b) are a plan view and a side view of the measuring or reference electrode of Fig. L (b),
• Fig. 6 is a schematic representation of the structure of a flow measuring arrangement
• Fig. 7 is a schematic representation of the structure of a further flow measuring arrangement
• the carrier consists of a hollow cylindrical rod 4 made of polyvinyl chloride (PVC).
• a region 6 of larger diameter adjoins the front region of the rod 4 facing the measuring liquid.
• the cavity inside the rod 4 is cylindrical with different inner diameters.
• the sleeve 16 is set back adjacent to the front end of the rod 4 and has an axial flange 18 which is flush with the front end of the rod 4.
• FIG. 1 (b) and 3 (a) and (b) show a measuring electrode or reference electrode, both of which are of the same construction. They each comprise a wire 20 which has a bent section 22 at the front end. In the arrangement shown, the measuring electrode and the reference electrode are arranged diametrically to one another directly after the rod 4. * The electrode materials are platinum for the measuring electrode and Ag / AgCl for the reference electrode.
• the auxiliary electrode is designed as a plate 30 made of gold.
• the plate 30 has on the rear side a pin 32 which is screwed into a protruding pin 34 with a larger diameter.
• the pin 34 protrudes from a rod-shaped conductor 36 made of copper.
• the plate 30 of the auxiliary electrode is inserted centrally in the front end of the rod 4.
• the rod 36 provided with the pin 34 is inserted from the rear and then the two pins 32 and 34 are screwed together.
• the reference and reference electrodes are mounted and then the sleeve 16 is screwed on.
• the auxiliary electrode has a continuous cylindrical section 38.
• the sleeve 15 is flat and screwed onto the section 38.
• REPLACEMENT LEAF 6 shows the measuring electrode arrangement according to the invention installed in a flow measuring chamber 40.
• the flow measuring chamber 40 consists of acrylic glass and has a cylindrical bore 42 on one end for the measuring electrode arrangement 44. On the opposite side, the flow measuring chamber 40 is provided with a further bore 46.
• a line 48 runs through the bore 46 and leads the measuring solution to the measuring electrodes and removes it. In this way, the electrodes can be rinsed with a small sample volume.
• FIG. 7 shows another example of a flow measuring chamber 50 with a built-in measuring electrode arrangement 44. Insofar as the same parts are present, they will not be described again.
• the line 52 continuing the measuring solution from the measuring electrode arrangement 44 is shown with an outlet bore 54.
• the invention relates to a measuring electrode arrangement for measuring in liquids.
• the measuring electrode arrangement comprises a working, an auxiliary and a reference electrode, each made of metal and installed in a carrier made of plastic material. With this arrangement, no electrolyte bridge is required and the dimensions can be greatly reduced.

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Health & Medical Sciences (AREA)
• Physics & Mathematics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Molecular Biology (AREA)
• Analytical Chemistry (AREA)
• Biochemistry (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Applications Claiming Priority (2)

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Cited By (3)

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• 1989
  • 1989-09-27 DE DE19893932246 patent/DE3932246A1/de active Granted
• 1990
  • 1990-09-27 EP EP19900913702 patent/EP0445249A1/de not_active Withdrawn
  • 1990-09-27 JP JP2512867A patent/JPH04502064A/ja active Pending
  • 1990-09-27 WO PCT/EP1990/001633 patent/WO1991005248A1/de not_active Application Discontinuation

Patent Citations (1)

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