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Simultaneous dual excitation/single emission fluorescent sensing method for PH and pCO.sub.2

  • US 5,672,515 A
  • Filed: 09/12/1995
  • Issued: 09/30/1997
  • Est. Priority Date: 09/12/1995
  • Status: Expired due to Fees
First Claim
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1. A method for quantitating an analyte in a sample, comprising:

  • (a) providing an optical sensor comprising an optical fiber means having a distal end portion for contacting the fluid sample, and a proximal end portion for communication with a means for receiving a signal from the distal end portion, and wherein the distal end portion has an analyte sensing means comprising an indicator species having an absorption or excitation spectrum that includes a first region and a second region and wherein the first and second regions do not overlap substantially, and an emission spectrum that is distinct from the absorption or excitation spectrum;

    (b) contacting the sample with the distal end portion of the optical sensor;

    (c) simultaneously exciting the indicator species using modulated radiation of a first optical wavelength corresponding to the first region, thereby producing a first modulated indicator emission signal, and modulated radiation of a second optical wavelength corresponding to the second region, thereby producing a second modulated indicator emission signal, wherein the radiation of first and second optical wavelengths are respectively transmitted at first and second electrical frequencies;

    (d) demodulating the first and second modulated indicator emission signals;

    (e) calculating the apparent quantity of analyte present in the sample from the first and second indicator emission signals; and

    (f) correcting the apparent quantity of analyte present for variations resulting from external factors, by determining the ratio of the first and second indicator emission signals.

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