Method and apparatus for determination of a constituent in a fluid
First Claim
1. A method of amperemetric detection of at least one constituent of a fluid sample of animal or human whole blood by means of a measuring apparatus containing an integrated electrode device including at least one enzyme sensor electrode and a reference electrode having an exposed surface part at a free end portion of the integrated electrode device and extending longitudinally through said end portion, said method being characterized in that the reference electrode used is an Ag/AgCl electrode working at a chloride ion concentration of about 145 meq/l and that before applying the sample on the exposed surface of the electrode device, said electrode device is moved longitudinally outward by an increment and subsequently the outer end section of said free end portion of the integrated electrode device is removed by means of removing means mounted movably on the measuring apparatus, so as to provide a new exposed surface part of the integrated electrode device, and that subsequently said new exposed surface part of the integrated electrode device is exposed to said fluid sample, so as to generate a measuring signal representative of said constituent of the sample.
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Abstract
A method is provided for measuring the concentration of a constituent of a fluid sample, e.g. glucose in a glucose-containing blood sample, by means of an electrode device. Also provided are an electrode device comprising the electrodes used in the method, a sensor electrode for use in the method, and an apparatus for use in the measurement of the concentration of the constituent in the sample.
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Citations
47 Claims
- 1. A method of amperemetric detection of at least one constituent of a fluid sample of animal or human whole blood by means of a measuring apparatus containing an integrated electrode device including at least one enzyme sensor electrode and a reference electrode having an exposed surface part at a free end portion of the integrated electrode device and extending longitudinally through said end portion, said method being characterized in that the reference electrode used is an Ag/AgCl electrode working at a chloride ion concentration of about 145 meq/l and that before applying the sample on the exposed surface of the electrode device, said electrode device is moved longitudinally outward by an increment and subsequently the outer end section of said free end portion of the integrated electrode device is removed by means of removing means mounted movably on the measuring apparatus, so as to provide a new exposed surface part of the integrated electrode device, and that subsequently said new exposed surface part of the integrated electrode device is exposed to said fluid sample, so as to generate a measuring signal representative of said constituent of the sample.
- 16. An electrode device for amperemetric detection of at least one constituent of a fluid sample of animal or human whole blood, said device comprising an electrode body member (16) having a free end portion (21), at least one sensor electrode (18) extending axially through said end portion and having a cross-sectional area within said end portion, and a reference electrode which is uniform to close to uniform (19) also extending axially through the free end portion (21) of the electrode body member, each electrode being received in a bore extending longitudinally through the electrode body member and having an exposed surface part at the free end portion of the electrode body member, characterized in that the reference electrode is an Ag/AgCl electrode and that the sensor electrode is an electrically conductive electrode comprising a paste of electrically conductive particles and a pasting material containing an oxidase enzyme and a charge-transfer mediator, being distributed in the paste and in its reduced form being dissolved in the pasting material in a concentration which is at least sufficient to ensure that the concentration of the charge-transfer mediator in its oxidized form is constant or close to constant at the exposed surface of the sensor electrode during the measurement, the charge-transfer mediator in its reduced form optionally further being present in undissolved form in the paste.
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27. A measuring apparatus for measuring at least one constituent of a fluid sample of animal or human whole blood, characterized in that it comprises
a body member (10) defining an outwardly open cavity (14) for receiving an electrode device (15) therein, removing means (27) mounted on the body member (10) so as to be movable in relation thereto along a path intersecting said cavity (14) for removing an outer end section from a free end portion of the electrode device (15) received in the cavity (14), means (30-34 and 37) for moving the electrode device outwardly by an increment each time the removing means has been operated, an electronic measuring circuitry (35) for processing measuring signals received from the electrode or electrodes of the electrode device, and connecting means for electrically connecting the electrode or electrodes of the electrode device to the electronic measuring circuitry when the electrode device is received in said cavity.
Specification