Nitric oxide detection
First Claim
1. A method of determining the concentration of nitric oxide in a gaseous sample, wherein the method comprises the following steps:
- a) collecting a gaseous sample containing nitric oxide,b) exposing the sample to a first substrate to which nitric acid is bound in the presence of water to form nitrogen dioxide by reaction with the nitric oxide,c) exposing the nitrogen dioxide to a second substrate (17) which is associated with a reducing agent so as to form amplified nitric oxide from any nitrogen dioxide present, andd) determining the concentration of nitric oxide in the gaseous sample from the amplified nitric oxide-produced in step,wherein the first and second substrates are comprised in a same substrate.
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Abstract
The present invention relates to a method for amplifying the detected signal in a gas sensor. More specifically, the present invention relates to a method for increasing the concentration of the gas which is being detected in a sample or increasing the concentration of a gas which is directly obtained from the gas in the sample by chemical reaction. The gas which is to be detected is nitric oxide (NO). In particular, the method concerns the selective conversion of NO to NO2 which allows a threefold amplification of the number of analyte molecules in NO trace gas analysis in a single amplification cycle. Subsequent reduction or thermal decomposition of the obtained NO2 can provide NO again, which can again be introduced in a new amplification cycle. Multiple (n) amplification cycles can provide a sensitivity amplification by a factor 3n. The method can be combined with a multitude of detection methods and tolerates a high humidity. The method is therefore of general use in the analysis of NO from a variety of sources.
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Citations
13 Claims
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1. A method of determining the concentration of nitric oxide in a gaseous sample, wherein the method comprises the following steps:
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a) collecting a gaseous sample containing nitric oxide, b) exposing the sample to a first substrate to which nitric acid is bound in the presence of water to form nitrogen dioxide by reaction with the nitric oxide, c) exposing the nitrogen dioxide to a second substrate (17) which is associated with a reducing agent so as to form amplified nitric oxide from any nitrogen dioxide present, and d) determining the concentration of nitric oxide in the gaseous sample from the amplified nitric oxide-produced in step, wherein the first and second substrates are comprised in a same substrate. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus for measuring the concentration of nitric oxide in a gaseous sample, the apparatus including the following components arranged in fluid communication:
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a vessel for collecting a gaseous sample containing nitric oxide; a reaction chamber in fluid communication with the vessel containing a first substrate whose surface is able to provide a source of nitric acid and water enabling the formation of nitrogen dioxide after exposition of the sample to the first substrate; a second substrate, the surface of which includes a reducing agent which forms amplified nitric oxide once in contact with the nitrogen dioxide; and
,means for determining the concentration of the nitric oxide from the amplified nitric oxide, wherein the first and second substrates are intimately mixed. - View Dependent Claims (7, 12)
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8. An apparatus for measuring the concentration of nitric oxide in a gaseous sample, the apparatus including the following components arranged in fluid communication:
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a vessel for collecting a gaseous sample containing nitric oxide; a reaction chamber in fluid communication with the vessel, the reaction chamber containing a first substrate, the first substrate being provided with a first substrate surface having a source of nitric acid and water enabling the formation of nitrogen dioxide after exposition of the sample to the first substrate and containing a second substrate, a second substrate surface of the second substrate including a reducing agent capable of forming amplified nitric oxide once in contact with the nitrogen dioxide; and
,means for determining the concentration of the nitric oxide from the nitrogen dioxide, wherein the first and second substrates are comprised in a column, and wherein the first and second substrates are intimately mixed. - View Dependent Claims (9, 10, 11, 13)
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Specification