Method and system for sampling and determining the presence of compounds

A system for detecting selected compounds in a sample by chemiluminescent gas phase reaction with a reactant comprising:

• means for collecting the sample;
• means for dividing the sample into first and second portions;
• first converter means for hearing the first portion of the sample to a first predetermined temperature, said first converter means having first conversion properties with respect to the selected compounds;
• second converter means for heating the second portion of the sample to a second predetermined temperature, said second converter means having second conversion properties with respect to the selected compounds which are different from the first conversion properties of the first converter means;
• means for 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;
• means for 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;
• means for selectively detecting radiation emitted by chemiluminescence from a selected compound of the first portion of the sample;
• means for selectively detecting radiation emitted by chemiluminescence from the conversion of selected compounds and at least the same compound in the first portion in the second portion of the sample;
• means for generating first electrical signals having amplitudes and durations related to the detected characteristic wavelengths of radiation emitted from the mixed first portion of the sample and second electrical signals having amplitudes and durations related to the detected characteristic wavelengths of radiation emitted from the mixed second portion of the sample;
• and
• means for comparing the first electrical signals with the second electrical signals in order to determine the presence or absence of selected compounds in the sample;
• said heating, mixing, detecting, and generating means being operable to process said first portion at substantially the same relative times as the processing of said second portion to thereby permit cancellation of signals related to background components from said first and second electrical signals by said comparing means.

A method of detecting selected compounds in a sample by chemiluminescent gas phase reaction of a compound which might be present as a background component of the sample, and as a converted product of one of said selected compounds, with a chemical 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 a first conversion properties such that no appreciable amounts of the compound in the background component can be produced thereby conversion of the selected components;
• heating the second portion of the sample to a second predetermined temperature in a second pyrolyzer having second conversion properties such that the measurable amounts of the compound from the background component, and also from converted products of the selected compounds can be produced;
• mixing the heated first portion of the sample with said chemical reactant to cause a chemical reaction therewith in order to generate radiation by chemiluminescence having characteristic wavelengths related to a compound of the background component in said first portion;
• mixing the heated second portion of the sample with said chemical reactant to cause a chemical reaction therewith in order to generate radiation by chemiluminescence having characteristic wavelengths related to the background component of the compound, and the compound produced by conversion of the selected compounds in said second portion;
• selectively detecting radiation emitted by chemiluminescence from the background component in the first portion of the sample;
• selectively detecting radiation emitted by chemiluminescence from the converted products of the selected compounds in the second portion of the sample as well as said background components in the second portion;
• 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 with the second electrical signals so as to cancel signals related to said compound in the background component in said portions.