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Electrochemical sensor system

  • US 9,523,667 B2
  • Filed: 08/13/2012
  • Issued: 12/20/2016
  • Est. Priority Date: 08/15/2011
  • Status: Active Grant
First Claim
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1. A method of measuring concentration of hydrogen sulfide or thiol analyte in a subterranean test fluid at a temperature of 50°

  • to 125°

    C. in a well comprising;

    providing a plurality of electrodes in contact with an electrolyte solution containing a redox-active species electrochemically convertible between reduced and oxidized forms, wherein the electrolyte solution contains surfactant and at least one said form of the redox active species is present within surfactant micelles; and

    bringing the electrolyte and a test fluid containing the analyte into contact with opposite sides of a membrane, which is permeable to the hydrogen sulfide or thiol analyte so that analyte can migrate through the membrane into the electrolyte solution; and

    applying potential to the electrodes and observing current flow as voltage is varied;

    wherein the redox-active species comprises ferrocene which is substituted with at least one substituent group which is an alkyl group of 1 to 6 carbon atoms or an alkenyl group of 2 to 6 carbon atoms such that the water solubility of the substituted ferrocene is less than the water solubility of unsubstituted ferrocene; and

    wherein the substituted ferrocene is solubilized by the surfactant micelles.

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