METHOD FOR OPTICAL ACTIVATION OF THE SENSOR SURFACE, IN PARTICULAR FOR ZERO CHLORINE SENSORS

Abstract

The invention relates to the use of a physical-technological radiation source in a method for cleaning and conditioning a sensor of a measuring device for determining a constituent substance in a sample, a sensor and an electrochemical measuring device for carrying out said method.

Claims

1. A method for cleaning and conditioning an electrochemical sensor of a measuring device for determining a constituent substance of a sample, wherein the measuring device comprises: a) an electrolyte containing a chemical substance, b) the electrochemical sensor that comprises a measuring chamber (5) in which a working electrode (2) and a reference electrode (6) are disposed, between which an electrical signal can be detected in a measuring interval, from which the constituent substance can be inferred, wherein the method comprises the following steps: producing a conditioning agent from the chemical substance by irradiating the electrolyte with the physical-technological radiation source, and reducing the conditioning agent at the working electrode (2).

2. A method according to claim 1 wherein the chemical substance is a salt or the corresponding acid of a halide.

3. A method according to claim 1 wherein the conditioning agent is not produced during the measuring interval.

4. A method according to claim 1 wherein the conditioning agent is produced in a pulsed manner.

5. A method according to claim 1 wherein the irradiation is time-controlled.

6. A method according to claim 1 wherein 50% or more of the integral of the radiation spectrum of the physical-technological radiation source is in a wavelength range of <550 nm.

7. A method according to claim 1 wherein the constituent substance to be determined is used as the conditioning agent.

8. A method according to claim 1 wherein a detection electrolyte which comprises a component that is reduced or oxidised into a detection component by means of the constituent substance to be determined is used as the electrolyte.

9. A method according to claim 1 wherein the constituent substance to be determined is an oxidising agent, selected from the group consisting of oxidative halogen compounds of chlorine, bromine and iodine, chloramines and bromamines, Cl.sub.2, Br.sub.2, O.sub.3, ClO.sub.2, peracetic acid, H.sub.2O.sub.2, a chlorite or hypochlorite salt or the corresponding acid.

10. A method according to claim 1 further comprising subtracting an adjustment value from the electrical signal measured during the measuring interval, and determining the adjustment value by measuring the electrical signal during an adjustment interval in which no constituent substance to be determined is present.

11. A method according to claim 1 wherein the conditioning agent corresponds to the constituent substance to be determined of the sample and a quantity of conditioning agent is produced by irradiation in the measuring chamber (5) or a quantity of conditioning agent is produced by irradiation in a section of the measuring device and delivered to the measuring chamber (5) and the electrical signal is detected between the working electrode (2) and the reference electrode (6).

12. An electrochemical sensor comprising a measuring chamber (5) in which a working electrode (2) and a reference electrode (6) are disposed, between which an electrical signal can be detected in a measuring interval, from which the constituent substance can be inferred, and a physical-technological radiation source disposed inside the measuring chamber (5).

13. An electrochemical measuring device comprising an electrochemical sensor according to claim 12.

14. An electrochemical measuring device comprising a) an electrochemical sensor comprising a measuring chamber (5) in which a working electrode (2) and a reference electrode (6) are disposed, between which an electrical signal can be detected in a measuring interval, from which the constituent substance can be inferred, and b) a physical-technological radiation source

15. The electrochemical measuring device according to claim 13, wherein the measuring chamber (5) is sealed with a selectively permeable membrane (4).

16. The electrochemical measuring device according to claim 14, wherein the measuring chamber (5) is sealed with a selectively permeable membrane (4).

17. A method according to claim 5 wherein the irradiation is time-controlled with fixed time intervals between successive irradiation periods.

18. A method according to claim 6 wherein 50% or more of the integral of the radiation spectrum of the physical-technological radiation source is in a wavelength range of <500 nm.

19. A method according to claim 1 wherein the chemical substance is selected from the group consisting of HI and KI.

20. An electrochemical sensor according to claim 12 wherein said source is disposed in an electrode body which comprises the working electrode (2) and the reference electrode (6).

Description

[0083] FIG. 1: Schematic illustration of a specific embodiment of a measuring chamber according to the invention comprising a selectively permeable membrane and a physical-technological radiation source disposed inside said measuring chamber.

[0084] FIG. 2: Schematic illustration of a specific embodiment of a measuring chamber according to the invention comprising a selectively permeable membrane and a physical-technological radiation source disposed outside said measuring chamber.

[0085] FIG. 1 shows a schematic illustration of a measuring chamber 5 of an electrochemical sensor according to the invention, which comprises a selectively permeable membrane 4 and an electrode body. This electrode body comprises a working electrode 2, an associated reference electrode 6 and a physical-technological radiation source 1. The cylindrical working electrode 2 is disposed inside the hollow cylindrical reference electrode 6. They are connected to one another via a measuring device (not shown), so that an electrical signal can be detected during a measuring interval, from which the presence of a constituent substance in the sample can be inferred. The physical-technological radiation source is an LED 1 that emits white or UV light and is disposed in a blind hole of the electrode body. The electrode body is connected to the electronics in the upper part (not shown) and, together with the two electrodes and the LED, is immersed into the membrane cap filled with electrolyte and is tightly screwed to it. These components together form the measuring chamber 5. The physical-technological radiation source irradiates a portion of the electrolyte 3 disposed inside the measuring chamber 5, so that the conditioning agent is produced from the chemical substance contained in the electrolyte. This conditioning agent then diffuses to the working electrode 2 and is reduced there, so that the conditioning effect occurs there. The selectively permeable portion of the membrane 4, which is not covered by the mask 8, is smaller than the base surface of the cylinder of the working electrode 2 and is disposed such that its projection onto the base surface of the working electrode 2 is at least 90% on the base surface of the working electrode.

[0086] FIG. 2 shows a schematic illustration of a measuring chamber 5 of an electrochemical sensor according to the invention comprising a selectively permeable membrane 4, a working electrode 2, and the associated reference electrode 6. The cylindrical working electrode 2 is disposed inside the hollow cylindrical reference electrode 6. They are connected to one another via a measuring device, so that an electrical signal can be detected during a measuring interval, from which the presence of a constituent substance in the sample can be inferred (not shown). The physical-technological radiation source is an LED 1 that emits white or UV light and is disposed outside the measuring chamber 5, e.g., in an inflow plug 7 of the measuring device. The radiation cone is oriented toward the measuring chamber 5, so that the radiation passes through the at least partially radiation-permeable membrane 4 and the conditioning agent is produced by a photoinduced reaction. This conditioning agent then diffuses to the working electrode 2 and is reduced so that the conditioning effect occurs. The selectively permeable portion of the membrane 4, which is not covered by the mask 8, is smaller than the base surface of the cylinder of the working electrode 2 and is disposed such that its projection onto the base surface of the working electrode 2 is at least 90% on the base surface of the working electrode 2.

REFERENCE SIGNS

[0087] 1 LED (UV or white light) in a blind hole [0088] 2 Working Electrode [0089] 3 Electrolyte [0090] 4 Membrane [0091] 5 Measuring chamber [0092] 6 Reference Electrode [0093] 7 Inflow plug [0094] 8 Mask