Method of regenerating amperometric sensors

Abstract

A method for regenerating an amperometric sensor involves bringing the electrodes of the sensor into contact with an active, complex-forming regenerating solution and connecting the electrodes into an adjustable electric circuit. This forms an electrochemical cell. Then, at least one negative and/or positive voltage pulse is applied to the electrochemical cell to either oxidize or reduce deposits on at least one of the electrodes into a deposit product, which is dissolved into the regenerating solution. The electrodes are removed from the regenerating solution and from the electric circuit, rinsed with a rinsing solution, and dried. After this, the electrodes are brought into contact with the sensor electrolyte and their functionality is verified. A device for performing this method is also provided.

1 . A method for regenerating an amperometric sensor comprising an electrolyte and at least one electrode immersed in the electrolyte during operation of the sensor, the at least one electrode comprising at least one of: a working electrode, a counter electrode and a reference electrode, the method comprising the steps of:
 contacting the electrodes with a chemically active regenerating solution and connecting the electrodes into an adjustable electric circuit, thereby forming an electrochemical cell, the regenerating solution comprising a complexing agent;   applying a voltage pulse, of either positive or negative voltage, to the electrochemical cell to either oxidize or reduce deposits on the electrodes into at least one deposit product;   reacting the at least one deposit product with the regenerating solution, resulting in dissolving the at least one deposit product in the regenerating solution;   removing the electrodes from both the regenerating solution and the electric circuit;   rinsing the electrodes with a rinsing solution and drying the electrodes; and   bringing the electrodes into contact with the operating electrolyte and verifying the overall functionality of the electrode.   
   
   
       2 . The method of  claim 1 , further comprising the steps of:
 preparing the electrodes, prior to the contacting step, by removing a membrane body from the sensor, thereby exposing the electrodes; and   reinstalling the removed membrane body after removing the electrodes from the regenerating solution.   
   
   
       3 . The method of  claim 2 , wherein:
 the voltage pulse applying step lasts from about 15 to about 300 sec.   
   
   
       4 . The method of  claim 3 , wherein:
 the voltage pulse has a magnitude in the range of from about −3 V to about +3 V.   
   
   
       5 . The method of  claim 1 , wherein:
 the voltage pulse applying step lasts from about 15 to about 300 sec.   
   
   
       6 . The method of  claim 1 , wherein:
 the voltage pulse has a magnitude in the range of from about −3 V to about +3 V.   
   
   
       7 . The method of  claim 1 , further comprising the step of:
 polarizing and/or recalibrating the electrodes prior to and/or after verifying the functionality thereof.   
   
   
       8 . The method of  claim 1 , wherein:
 the step of verifying the functionality of the electrodes comprises the substeps of determining at least one of: the slope, a reference potential, the response behavior and the stability of the measurement signal of the electrochemical cell.   
   
   
       9 . The method of  claim 1 , wherein:
 the regenerating solution is an aqueous solution of sodium thiosulfate.   
   
   
       10 . A device for regenerating an amperometric sensor using the method of  claim 1 , the device comprising:
 a container adapted to be filled with a chemically active regenerating solution; and   a source of adjustable voltage for applying a voltage pulse to the electrodes, the voltage source arranged to be connected to the electrodes while the electrodes are immersed in the regenerating solution.