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Method and system for sampling and determining the presence of compounds

  • US 5,567,623 A
  • Filed: 04/04/1995
  • Issued: 10/22/1996
  • Est. Priority Date: 06/01/1992
  • Status: Expired due to Term
First Claim
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1. A method of detecting selected compounds in a sample by chemiluminescent gas phase reaction with a reactant comprising the steps of:

  • collecting the sample;

    dividing the sample into first and second portions;

    heating the first portion of the sample to a first predetermined temperature in a first pyrolyzer having first conversion properties with respect to the selected compounds;

    heating the second portion of the sample to a second predetermined temperature in a second pyrolyzer having second conversion properties with respect to the selected compounds which are different from the first conversion properties of the first pyrolyzer;

    mixing the heated first portion of the sample with the reactant to cause a chemical reaction therewith in order to generate radiation by chemiluminescence having characteristic wavelengths related to substances in said first portion;

    mixing the heated second portion of the sample with the reactant to cause a chemical reaction therewith in order to generate radiation by chemiluminescence having characteristic wavelengths related to substances in said second portion;

    selectively detecting radiation emitted by chemiluminescence from a selected compound in the first portion of the sample;

    selectively detecting radiation emitted by chemiluminescence from conversion of the selected component in the second portion of the sample and at least the same compound in the first portion of the sample in the second portion of the sample;

    generating first electrical signals from the radiation selectively detected from the first portion of the sample and second electrical signals from the radiation selectively detected from the second portion of the sample; and

    comparing the first electrical signals with the second electrical signals in order to determine the presence or absence of selected compounds in the sample;

    wherein said heating, mixing, detecting, and generating steps are performed at substantially the same times for said first portion as for said second portion and wherein the step of comparing includes the steps of comparing the first electrical signals and the second electrical signals so as to cancel signals related to said portions of background components.

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