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Method for the detection of noxious gases

  • US 4,797,180 A
  • Filed: 06/04/1987
  • Issued: 01/10/1989
  • Est. Priority Date: 07/29/1985
  • Status: Expired due to Fees
First Claim
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1. A method for quantitatively detecting a noxious gas in air in an electrochemical cell comprising a first working electrode, a second working electrode, a counter electrode and a reference electrode, said first working electrode comprising a gas diffusion membrane having bonded thereto a catalytic portion electrochemically reactive with the noxious gas and said second working electrode having electrochemical activity with oxidation/reduction products produced at the first working electrode;

  • an electrolyte in contact with the catalytic portion of the first working electrode and in contact with second working electrode, the counter electrode and the reference electrode; and

    means for containing the electrolyte and said electrodes;

    said method comprising;

    (a) feeding an air sample containing the noxious gas to be detected to the first working electrode of said cell;

    (b) maintaining the first working electrode by means of a potentiostat at a fixed potential relative to the reference electrode of from about 1.0 to 1.8 volts with respect to the potential of the reversible hydrogen couple in the electrolyte of said cell to oxidize the noxious gas;

    (c) maintaining the second working electrode by means of a potentiostat at a fixed potential relative to the reference electrode of from above 1.0 to about 2.2 volts with respect to the potential of the reversible hydrogen couple in the electrolyte of said cell to further oxidize/reduce the oxidation/reduction products of the noxious gas to minimize the contamination of the electrolyte and the counter electrode, the fixed potential on said second working electrode being maintained at a voltage higher than the fixed potential being maintained on said first working electrode; and

    (d) measuring the current flowing between said first working electrode and said counter electrode to quantitatively determine the amount of the noxious gas in said air, said measured current being a measure of the concentration of the noxious gas in said air sample being detected.

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