Portable analytical system for detecting organic chemicals in water
First Claim
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1. A portable field system for detecting trihalo-methane compounds in water comprising:
- a preconcentrator for collecting the trihalomethane compounds found in the water, wherein the preconcentrator includes one or more metal collection tubes containing therein a dual bed including a porous polymer resin material followed by a carbon-based adsorbent resin;
a recirculation loop for circulating carrier gas exiting the preconcentrator back through the preconcentrator;
a gas chromatograph column for separating the compounds as desorbed from the preconcentrator; and
a surface acoustic wave detector for determining the mass of the compounds separated by the gas chromatograph, wherein the surface acoustic wave detector has a sensing surface with a nanoporous carbon coating.
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Abstract
A portable analytical system for detecting organic chemicals in water comprising a miniature preconcentrator and a SAW detector, the latter being characterized by a nanoporous carbon coating that provides improved response compared to prior art polymer coatings, particularly when detecting low concentrations of trihalomethane chemicals, such as chloroform and bromoform.
65 Citations
19 Claims
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1. A portable field system for detecting trihalo-methane compounds in water comprising:
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a preconcentrator for collecting the trihalomethane compounds found in the water, wherein the preconcentrator includes one or more metal collection tubes containing therein a dual bed including a porous polymer resin material followed by a carbon-based adsorbent resin; a recirculation loop for circulating carrier gas exiting the preconcentrator back through the preconcentrator; a gas chromatograph column for separating the compounds as desorbed from the preconcentrator; and a surface acoustic wave detector for determining the mass of the compounds separated by the gas chromatograph, wherein the surface acoustic wave detector has a sensing surface with a nanoporous carbon coating. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A portable field instrument for detecting purgeable trihalomethane compounds in water, comprising:
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a sample vessel wherein chemicals are purged from the water and entrained in a carrier gas; a preconcentrator connected to the sample purger for adsorbing the chemicals from the carrier gas, wherein the preconcentrator includes one or more metal collection tubes containing therein a dual bed including a porous polymer resin material followed by a carbon-based adsorbent resin; a recirculation loop for circulating carrier gas exiting the preconcentrator back through the sample vessel; a heater for heating the preconcentrator for desorbing the trihalomethane compounds; a gas chromatograph column to which the desorbed compounds are passed from the preconcentrator; a heater for heating the gas chromatograph column for causing the compounds to desorb after different retention times in the gas chromatograph column; and a surface acoustic wave detector to which the compounds are sequentially passed from the gas chromatograph column, the frequency of the surface acoustic wave detector changing as a function of the mass of compound adsorbed and desorbed from a sensing surface of the surface acoustic wave detector, whereby the mass quantity of the compounds is measured by the change of frequency of the surface acoustic wave device, wherein the surface acoustic wave detector has a sensing surface with a nanoporous carbon coating. - View Dependent Claims (17, 18)
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19. A method for detecting in the field organic trihalomethane compounds in water comprising:
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bringing a portable field instrument to a testing site; using a preconcentrator in the instrument to collect the trihalomethane compounds from in the water, wherein the preconcentrator includes one or more metal collection tubes containing therein a dual bed including a porous polymer resin material followed by a carbon-based adsorbent resin; using a recirculation loop in the instrument to circulate carrier gas exiting the preconcentrator back through the preconcentrator; using a gas chromatograph column in the instrument to separate the compounds as desorbed from the preconcentrator; and using a surface acoustic wave detector in the instrument to determine the mass of the compounds separated by the gas chromatograph, wherein the surface acoustic wave detector has a sensing surface with a nanoporous carbon coating.
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Specification