Selective, high speed detection of vapors with analysis of multiple GC-separated portions
First Claim
1. A method of rapidly and selectively detecting first and second specific compounds in a gas sample, said compounds being separable by gas chromatography and said first compound having a volatility substantially higher than the volatility of said second compound, comprising:
- trapping vapors of said specific compounds in a vapor concentrator;
and while flowing a carrier gas through the vapor concentrator, forming and analyzing a first portion of a gas sample containing said first specific compound during a first interval of time and thereafter forming and analyzing a second portion of a gas sample containing said second specific compound during a second interval of time;
said forming and analyzing of the first portion comprising the steps of (a) flash-heating the vapor concentrator to a first temperature effective to remove volatile materials including said first specific compound from said vapor concentrator with said flow of carrier gas without removing said second specific compound, (b) gas chromatographically (GC)-separating said first portion in a gas chromatograph connected to said vapor concentrator, and (c) detecting said first specific compound in said GC-separated first portion;
said forming and analyzing of the second portion comprising the steps of (a) flash-heating the vapor concentrator to a second temperature higher than said first temperature to form said second portion, (b) gas chromatographically (GC)-separating said second portion, and (c) detecting said second specific compound in said GC-separated second portion.
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Abstract
A method and apparatus for selective, high speed detection of vapors of specific gas-chromatographically-separable compounds. In the disclosed method separate analyses are performed on two portions of a gas sample formed by flash-heating trapped vapors to successively higher temperatures while flowing hydrogen carrier gas over coatings in/on which the vapors are held. Within a total time interval of about twenty seconds 1) two sample portions are formed, 2) each portion is rapidly separated in two series-connected, high speed, temperature-programmed gas chromatographs, and 3) specific compounds are identified by detection of NO gas formed during an oxidative pyrolysis of each separated portion. One application of the described method and apparatus is the rapid, selective, and sensitive detection of nitrogen-containing compounds such as the drugs methamphetamine, cocaine, and heroin.
92 Citations
16 Claims
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1. A method of rapidly and selectively detecting first and second specific compounds in a gas sample, said compounds being separable by gas chromatography and said first compound having a volatility substantially higher than the volatility of said second compound, comprising:
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trapping vapors of said specific compounds in a vapor concentrator; and while flowing a carrier gas through the vapor concentrator, forming and analyzing a first portion of a gas sample containing said first specific compound during a first interval of time and thereafter forming and analyzing a second portion of a gas sample containing said second specific compound during a second interval of time; said forming and analyzing of the first portion comprising the steps of (a) flash-heating the vapor concentrator to a first temperature effective to remove volatile materials including said first specific compound from said vapor concentrator with said flow of carrier gas without removing said second specific compound, (b) gas chromatographically (GC)-separating said first portion in a gas chromatograph connected to said vapor concentrator, and (c) detecting said first specific compound in said GC-separated first portion; said forming and analyzing of the second portion comprising the steps of (a) flash-heating the vapor concentrator to a second temperature higher than said first temperature to form said second portion, (b) gas chromatographically (GC)-separating said second portion, and (c) detecting said second specific compound in said GC-separated second portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of rapidly and selectively detecting one or more of the compounds methamphetamine, cocaine, and heroin comprising:
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(a) directing air containing vapors of one or more of said compounds into a vapor concentrator so as to trap said vapors in said vapor concentrator; (b) while flowing a carrier gas through the vapor concentrator and through a gas chromatograph connected to said vapor concentrator, flash-heating said vapor concentrator to a first temperature effective to remove vapors of methamphetamine, if present, from said vapor concentrator substantially without removing vapors of cocaine or heroin from said vapor concentrator; (c) gas chromatographically (GC)-separating said vapors of methamphetamine, if present, from other materials removed from said vapor concentrator as a result of said flash-heating step; (d) analyzing the effluent of said gas chromatograph to detect methamphetamine, if present, in said effluent; (e) flash-heating said vapor concentrator to a second temperature to remove vapors of cocaine and heroin, if present, from said vapor concentrator; (f) GC-separating said vapors of cocaine and heroin, if present, from each other and from other materials removed from said vapor concentrator in said second flash-heating step; and (g) analyzing the effluent of said gas chromatograph to detect cocaine and heroin, if present, in said effluent. - View Dependent Claims (15, 16)
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Specification