WO1988005911A1 - Optical carbon monoxide sensors impregnated on porous monolithic substrates - Google Patents
Optical carbon monoxide sensors impregnated on porous monolithic substrates Download PDFInfo
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- WO1988005911A1 WO1988005911A1 PCT/US1988/000217 US8800217W WO8805911A1 WO 1988005911 A1 WO1988005911 A1 WO 1988005911A1 US 8800217 W US8800217 W US 8800217W WO 8805911 A1 WO8805911 A1 WO 8805911A1
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- chloride
- group
- perchlorate
- acid
- reagent system
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
- G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
- G01N21/783—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour for analysing gases
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N31/00—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods
- G01N31/22—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators
- G01N31/223—Investigating or analysing non-biological materials by the use of the chemical methods specified in the subgroup; Apparatus specially adapted for such methods using chemical indicators for investigating presence of specific gases or aerosols
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
- G01N33/0036—Specially adapted to detect a particular component
- G01N33/004—Specially adapted to detect a particular component for CO, CO2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
Abstract
An improved device for detecting the presence of a reducing gas such as carbon monoxide or hydrogen sulfide. The device comprises a porous, monolithic substrate sufficiently transmissive to light to permit its detection by a phototransistor, and a self-regenerating chemical reagent system which changes optical density in response to contact with the reducing gas impregnated in the substrate. The chemical reagent system includes a compound(s) which render the chemical reagent system acid-retaining and/or acid-forming.
Description
OPTICAL CARBON MONOXIDE SENSORS IMPREGNATED ON POROUS MONOLITHIC SUBSTRATES
CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation in part of co- pending application Serial No. 010,786, the disόlosure of which is herein incorporated by reference.
FIELD OF THE INVENTION The present invention relates to an improved device for detecting the presence of a reducing gas by means of a chemical reagent system which changes optical density in response to the presence of reducing gas. The device is of particular use in detecting the presence of carbon monoxide or hydrogen sulfide.
DESCRIPTION OF THE PRIOR ART
The use of palladium and molybdenum salts for carbon monoxide detection is described i Analytical Chemistry, Volume 19, No. 2, pages 77 - 81 (1974). K. Shuler and G. Schrauzer improved upon this technology by adding a third metallic salt component which produces a self-regenerating catalyst of short life. This catalyst is the subject of U. S. Patent No. 4,043,934. This patent describes the impregnation of a carbon monoxide-
sensitive chemical catalyst solution into powdered- silica gel substrates to give detectors sensitive to low concentrations of atmospheric carbon monoxide. While this system is effective in detecting carbon monoxide it has not met with commercial acceptance due to the short working life of the catalyst.
It is generally recognized that for a carbon monoxide detection reagent system to be commercially useful it must have a working life of at least one year. Tests have shown that the material described in U. S. Patent No. 4,043,934 has a working life of two to four months at room temperature and only three to four days at forty degrees Celsius.
There therefore exists the need for a reagent system capable of detecting the presence of a reducing gas, such as carbon monoxide, which has a working life of at least one year.
SUMMARY OF THE INVENTION The present invention comprises a device for detecting the presence of a reducing gas, which has a working Life of at least one year. The device comprises a porous monolithic substrate sufficiently transmissive to light to permit its detection by a phototransistor or the like, and a self-regenerating chemical reagent system impregnated in the substrate, which changes optical density in response to contact with the reducing gas. The improvement which results in the increased working life of the chemical reagent system, lies in the inclusion in the chemical reagent system of a compound(s) which renders the chemical reagent system acid-retaining and/or acid-forming.
The present invention further comprises an improved chemical reagent system for the detection of the presence of a reducing gas.
DETAILED DESCRIPTION OF THE INVENTION
The present invention comprises an improved device for detecting the presence of a reducing gas, the device comprising a porous, monolithic substrate sufficiently transmissive to light to permit its detection by a phototransistor or the like; and a self-regenerating chemical reagent system which changes optical density in response to contact with the reducing gas to be detected, said chemical reagent system being impregnated into the substrate, the improvement comprising including in the chemical reagent system a compound(s) which renders the chemical reagent system acid-retaining and/or acid-forming.
The compound(s) is preferably water soluble and is preferably selected from the group consisting of lithium chloride, sodium chloride, lithium sulfate, lithium perchlorate, magnesium perchlorate, calcium perchlorate, aluminum perchlorate, platinum chloride, an inorganic acid, calcium chloride, magnesium chloride, cobalt chloride and combinations thereof. It is particularly preferred that ' the compound(s) is a nonvolatile inorganic acid, such as sulfuric acid or perchloric acid, or a halide salt such as calcium chloride, cobalt chloride and platinum chloride. It is preferable that the compound(s) is such that hydrochloric acid is either formed or retained in the chemical reagent system.
The porous monolithic substrate may be any of a number of commercially available porous monolithic materials which are optically transmissive. Examples include, but are not limited to, commercial silica gel dessicants in bead form (available from most major supplies of silica gel) , porous silicon dioxide and porous leached borosilicate glass such as VYCOR ("thirsty glass" — Corning Glass Works, Corning, New York. Brand No. 7930) . The porous glass may be
obtained in plate, rod or tubing form. Discs may be obtained by slicing the rods to suitable form. A variety of physical shapes and forms for the substrate may be obtained by suitable commercial processes. The chemical reagent system used to impregnate the porous monolithic substrate, with the exception of the compound(s) which renders the chemical reagent system acid-forming and/or acid retaining, may be composed of compounds disclosed in U.S. Patent No. 4,043,934. It is preferable that the chemical reagent system comprises a selection of at least one compound from each of the following groups:
Group 1 - palladium sulfate, palladium chloride, palladium bromide, palladium iodide, and palladium perchlorate;
Group 2 - silicomolybdic acid, salts of silicomolybdic acid, molybdenum trioxide, hetropolyacids of molybdenum, ammonium molybdate, alkali metal or alkaline earth metal salts of the molybdate anion; Group 3 - copper sulfate, copper chloride, copper bromide, copper iodide, and copper perchlorate; plus the compound(s) which renders the chemical reagent system acid retaining and/or acid forming. It is particularly preferred that the chemical reagent system used in the present invention comprises palladium chloride, silicomolybdic acid, copper chloride, and, as the acid-retaining and/or acid-forming chemical, calcium chloride.
In a preferred embodiment of the present invention the device further includes a hygroscopic agent, which is preferably a chloride. It is particularly preferred that the hygroscopic agent comprises a non-volatile source of halide.
In another preferred embodiment for the present invention the device includes absorbants to protect the
sensor from external contaminants and/or to inhibit the loss of acid and water from the sensor.
Typically, the porous monolithic substrate is impregnated with the chemical reagent system by immersing the substrate in a bath including at least one compound from each of the following groups:
Group 1 - palladium sulfate, palladium chloride, palladium bromide, palladium iodide, and palladium perchlorate; Group 2 - silicomolybdic acid, salts of silicomolybdic acid, molybdenum trioxide, hetropolyacids of molybdenum, ammonium molybdate, alkali metal or alkaline earth salts of the molybdate anion;
Group 3 - copper sulfate, copper chloride, copper bromide, copper iodide, artd copper perchlorate; and
Group 4 - lithium chloride, sodium chloride, • lithium sulfate, lithium perchlorate, magnesium perchlorate, calcium perchlorate, aluminum perchlorate, platinum chloride, an inorganic acid, calcium chloride, magnesium and cobalt chloride. The substrate is then removed from the bath and allowed to dry.
It is preferred that the bath includes compounds from each group in the following ratio range:
Group 1 : Group 2 - 0.01:1 to 0.5:1 Group 3 : Group 2 - 0.001:1 to 0.08:1
Group 4 : Group 2 - 0.01:1 to 10.0:1
It is also preferred that the Group 4 compound is calcium chloride.
It is also preferred that the compound(s) selected from Group 4 is present in at least a stoichemetric amount compared to the compound selected from Group 3.
In order that the nature of the present invention may be more clearly understood, preferred forms thereof will now be described with reference to the following examples.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Sensor devices were made by soaking pieces of porous VYCOR and silica gel beads for several hours in the following solutions and then letting the pieces dry in air. Measurements of optical response were made using standard laboratory instruments during periodic exposures to CO. Several example preparations of the monolithic sensors are presented below. Examples 1 through 3 were prepared by immersion of VYCOR into solution, the VYCOR is then removed and dried. Example 4 was made by placing porous silica beads in solution and then evaporating the solution.
The porous VYCOR discs have a diameter of approximately 0.25 inches and a thickness of 0.050 to 0.20 inches.
EXAMPLE 1 A solution composed of:
1.0 ml palladium sulfate (l%Pd in IN sulfuric acid)
0.25 ml palladium chloride (l%Pd in IN HC1) 6.0 ml silicomolybdic acid solution (50g/L) 1.0 ml IN HC1
4.4 ml copper chloride solution (10%w/v) into which are immersed six porous VYCOR discs having a diameter of approximately 0.25 inches and a thickness of 0.050 inches.
EXAMPLE 2
A solution composed of:
0.9 ml palladium sulfate (1% Pd in IN sulf ric acid) 15 ml silicomolybdic acid solution (50g/L)
4.5 ml lithium chloride solution (15.7g/L) 0.9 ml copper sulfate solution (439g/L) into which are immersed 21 porous VYCOR discs having a diameter of approximately 0.25 inches and a thickness of 0.050 inches.
EXAMPLE 3 A solution composed of:
1.2 ml palladium sulfate (l%Pd in IN sulfuric acid)
12 ml silicomolybdic acid_solution (50g/L) 2.4 ml lithium chloride solution (15.7g/L) 0.24 ml copper chloride solution (10% W/v) into which are immersed 18 porous VYCOR discs having a diameter of approximately 0.25 inches and a thickness of 0.050 inches.
EXAMPLE 4 A solution composed of: 65 mg palladium sulfate
12 mg Palladium chloride
10.0 ml silicomolybdic acid solution (50g/L) 1.0 ml IN HC1
1.0 ml copper chloride solution (10wt%) Traces of cobalt chloride and/or CaCl2 into which are immersed ten silica gel beads having a diameter of approximately 0.125 inches.
Sensors prepared with porous VYCOR according to
Example 4 and exposed to ambient conditions in excess of two years are proving to respond subsequently to low
levels of CO in air and regenerate for over 40 cycles. Sensors prepared according to Example 2 are proven to have lifetimes in excess of eight months. When such sensors are properly protected from environmental contaminants and heat they are expected to be capable of affording useful lifetimes of several years. One year is a commercially feasible minimum lifetime requirement for most chemical sensors application such as CO safety shutoff systems for gas appliances and CO alarm systems. CO sensors prepared with porous, monolithic VYCOR substrates therefore exhibit the lifetime requirements for a variety of commercial applications.
The use of material to inhibit ammonia and other basic gases from neutralizing the acid has also been shown to be effective. Copper salts have been shown to be effective for this purpose.
Testing of sensors made with porous, monolithic silica gel beads indicate that they remain viable much longer than sensors made with powdered silica gel substrates. Small quantities of powdered silica gel sensors exposed to the atmosphere have effective lifetimes ranging from two weeks to four months under laboratory and field conditions. Under similar conditions porous beads, prepared as described in Example 4, exhibit useful lifetimes greater than 20 months.
Studies have demonstrated that the aged CO sensor of U. S. 4,043,934 whether impregnated in silica gel, beads, or VYCOR can not be restored by addition of water once they fail. However, these same sensors have been restored by adding hydrogen chloride. This leads us to believe that the retention of HCl is the most important factor in lifetime extension.
The pH balance studies confirm that loss of HCl causes loss in sensitivity or auto darkening depending
on the particular formulation. The addition of cobalt chloride gives an indication of over heating by changing color at 60°C. This adds to the fail safe nature of the sensor. The addition of platinum chloride may act to hold
HCl by formation of complexes such as chloroplatinic acid (H2PtCl5#6H2θ) or platinum chloric acid (^PtClg-6H2O) and cobalt chloroplatinate.
Return of the porous, monolithic sensors to CO-free air permits the sensors to return to their initial optically transmissive states at a rate similar to clearing carboxyhe oglobin from the blood. They therefore display the desired self-regenerating properties for. commercial CO sensors. Our findings indicate that CO sensors comprised of porous, monolithic substrates and the chemical compositions described in the Examples represent substantial practical and useful improvements over the prior art.
Without wishing to be bound by scientific theory, we believe the observed enhancement of sensor lifetime may be due to an acid retaining and/or chloride acid replacement capability of the new formulation and the longer path for the volatile acid to exit this substrate. This may create a tortuous path by which molecules enter and leave the monolithic substrate, thus increasing substrate lifetime either by slowing down the departure of volatile components and/or by replacing the acid with excess acid forming compounds such as soluble chlorides. Tests in our lab indicate silica gel lifetime is extended with the addition of the agents, however, porous substrate life extension is even greater.
Additionally, the effective pore diameters of the monolithic materials may be important in extending the useful lifetimes of the sensors, presumably by promoting
the retention of acid and water. Tests indicate 10 to 100 angstroms pore size are preferred. Porous leached VYCOR is reported to have an average pore diameter of 40 angstroms with a void space of about 28% of its total volume. The silica gel beads are believed to have typical pore diameters of approximately 25 angstroms. Pore diameters between approximately 15 and 50 angstroms r are believed to facilitate the retention of acid and water. Surface area may be another important physical property of porous substrates. Porous VYCOR is reported to have a surface area of approximately 200 square meters/gram. Since this is a value typical of many powdered silica gel substrates, the surface area of VYCOR is not believed to contribute to its observed enhanced lifetime properties.
The sensitivity of our porous, monolithic sensors is not diminished by going to such substrates. They respond to low levels of CO at least as well as the powdered silica gel sensors of U. S. 4,043,934. The sensors typically show at least a fivefold drop in transmitted near-infrared radiation (as detected by silicon-based photo detectors) under the following conditions: 200 ppm CO (response <2 hours) ; 40 ppm CO (response <30 minutes) .
The monolithic nature of the sensor also facilitates light transmission through the sensor. Porous VYCOR and silica gel beads provide at least a tenfold increase in light transmission over powdered silica gel sensors of comparable thickness. The increased light transmission permits the use of low-cost conventional photo detectors which do not display significant temperature dependence. Our porous, monolithic sensors are therefore more amenable to
commercial applications than are powdered silica gel sensors.
In addition, tests show that the mass of the sensor, no matter which type, is proportional to lifetime and therefore monolithic materials will always be preferred. The mass of the particulate sensor must be low to be effective in an electrooptical system because the high light scattering efficiency of powdered silica gel sensors requires the use of very thin optical path lengths for the sensor. On the other hand, the greater light transmissivity of porous VYCOR and silica gel beads permits a thicker sensor containing a larger reservoir of chemical reagent to reside in the light path than does powdered silica gel. Studies clearly show that a more massive sensor will have longer life. This is b.elieved to account in part for the improved lifetimes of the porous, monolithic sensors.
Our porous, monolithic sensors also show other significant advantages over powdered silica gel sensors. Powdered silica gel substrates have a tendency to swell or contract appreciably depending upon the water content of the material. This property can affect the quality of particle packing within the sensor and can introduce cracking and light leaks. The bodies of porous, monolithic sensors are much more rigid and show little tendency to change their shape or size depending upon their water content. Futhermore, expensive porous windows required to retain the silica gel are not necessary to retain the porous, monolithic sensor. The physical properties of porous, monolithic sensors therefore making them more reliable and low-cost alternative to powdered silica gel sensors.
The addition of inorganic non volatile acids such as perchlorate and halide salts such as, CaCl ,
CoCl2, and/or PtCl2 to the basic chemical formulation described in U. S. 4,043,934 is believed to contribute most significantly to the useful lifetimes of the sensors. The presence of acid forming and retaining sulfuric acid, perchloric acid, lithium chloride, sodium chloride, magnesium chloride, calcium chloride, aluminum chloride, lithium perchlorate, magnesium perchlorate, calcium perchlorate, aluminum perchlorate, cobalt chloride, and platinum chloride is believed to assist in the retention of hydrogen chloride by a variety of mechanism .
The nonvolatile inorganic halides among the above group are also believed to extend the sensor lifetime by facilitating the retention of halide (chloride) in the sensor. Halide is believed to be important in maintaining the reversible nature of the sensor.
It will be readily appreciated by a person skilled in the art as to how the device of the present invention may be incorporated in a system for the detection of the presence for reducing gas. This may be done by providing a radiation source arranged such that radiation from the source is incident upon the device of the present invention and providing detection means for measuring the amount of radiation passing through the device of the present invention.
Claims
1. In a device for detecting the presence of a reducing gas, the device comprising a porous, monolithic 5 substrate sufficiently transmissive to light to permit its detection by a phototransistor; and a self- regenerating chemical reagent system which changes optical density in response to contact with the reducing gas to be detected, said chemical reagent system being 10 impregnated into the substrate, the improvement comprising including in the chemical reagent system a compoun (s) which renders the chemical reagent system acid-retaining and/or acid-forming.
15 2. A device as claimed in claim 1 in which the compound(s) is selected from the group consisting of lithium chloride, sodium chloride, lithium sulfate, lithium perchlorate, magnesium perchlorate, calcium perchlorate, aluminum perchlorate, platinum chloride, an
20 inorganic acid, calcium chloride, magnesium chloride, cobalt chloride and combinations thereof.
3. A device as claimed in claim 2 in which the compound(s) is selected from the group consisting of
25 calcium chloride, cobalt chloride, platinum chloride, sulfuric acid, perchloric acid and combinations thereof.
30
35
4. A device as claimed in claim 1 in which the chemical reagent system comprises a selection of at least one compound from each of the following groups:
Group 1 - palladium sulfate, palladium chloride, palladium bromide, palladium iodide and palladium perchlorate;
Group 2 - silicomolybdic acid, salts of silicomolybdic acid, molybdenum trioxide, hetrppolyacids of molybdenum, ammonium molybdate, alkali metal or alkaline earth salts of the molybdate anion;
Group 3 - copper sulfate, copper chloride, copper bromide, copper iodide, and copper perchlorate; and
Group 4 - lithium chloride, sodium chloride, lithium sulfate, lithium perchlorate, magnesium perchlorate, calcium perchlorate, aluminum perchlorate, platinum chloride, an inorganic acid, calcium chloride, magnesium chloride and cobalt chloride.
5. A device as claimed in claim 4 wherein the compound from Group 1 comprises palladium chloride.
6. A device as claimed in claim 4 or claim 5 in which the compound from Group 2 comprises silicomolybdic acid.
7. A device as claimed in any one of claims 4 to 6 in which the compound from Group 3 comprises copper chloride.
8. A device as claimed in any one of claims 4 to 7 in which the compound from Group 4 comprises calcium chloride.
9. A device as claimed in any one of claims 4 to 8 in which the compounds from Groups 1 to 4 are used in the following ratio range:
Group 1 : Group 2 - 0.01:1 to 0.5:1 Group 3 : Group 2 - 0.001 to 0.08:1 Group 4 : Group 2 - 0.01:1 to 10.0:1
10. A device as claimed in any one of claims 1 to 9 in which the compound is calcium chloride.
11. A device as claimed in any one of claims 1 to
10 in which the substrate is selected from the group consisting of porous silica gel beads, porous leached borosilicate glass, and porous silicon dioxide.
12. A device as claimed in any one of claims 1 to
11 in which the reducing gas to be detected is carbon monoxide or hydrogen sulfide.
13. A device as claimed in any one of claims 1 to
12 in which the device further includes a hygroscopic agent.
14. A device as claimed in claim 13 in which the hygroscopic agent comprises a chloride.
15. A device as claimed in claim 13 or 14 in which the hygroscopic agent comprises a nonvolatile source of halide.
16. A device as claimed in any one of claims 1 to 15 in which the device further includes absorbants which protect the substrate from external contaminants and/or inhibit the loss of acid and water from the substrate. -16-
17. A device as claimed in any one of claims 1 to 16 in which the compound is such that it causes the chemical reagent system to retain or form hydrochloric acid.
18. In a self-regenerating chemical reagent system which changes optical density in response to contact with a reducing gas, the improvement comprising including in the chemical reagent system a compound(s) which renders the chemical reagent system acid-retaining and/or acid-forming.
19. A chemical reagent system as claimed in claim 18 in which the compound(s) is selected from the group
' consisting of lithium chloride, sodium chloride, lithium sulfate, - lithium perchlorate, magnesium perchlorate, calcium perchlorate, aluminum perchlorate, platinum chloride, an inorganic acid, calcium chloride, magnesium chloride, cobalt chloride and combinations thereof.
20. The chemical reagent system as claimed in claim 19 in which the compound(s) is selected from the group consisting of calσium chloride, cobalt chloride, platinum chloride, sulfuric acid, perchloric acid and combinations thereof. -17-
21. A chemical reagent system as claimed in claim
18 in which the reagent system comprises a selection of at least one compound from each of the following groups:
Group 1 - palladium sulfate, palladium chloride, palladium bromide, palladium iodide, and palladium perchlorate;
Group 2 - silicomolybdic acid, salts of silicomolybdic acid, molybdenum trioxide, hetropolyacids of molybdenum, ammonium molybdate, alkali metal or alkaline earth salts of the molybdate anion;
Group 3 - copper sulfate, copper chloride, copper bromide, copper iodide, and copper perchlorate; and
Group 4 - lithium chloride, sodium chloride, lithium sulfate, lithium perchlorate, magnesium perchlorate, calcium perchlorate, aluminum perchlorate, platinum chloride, an inorganic acid, calcium chloride, magnesium chloride and cobalt chloride.
22. A chemical reagent system has claimed in any one of claims 18 to 21 in which the compound(s) is such that it causes the chemical reagent system to retain or form hydrochloric acid.
23. A device for detecting the presence of reducing gas substantially as hereinbefore described with reference to any one of Examples 1 to 4.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US1078687A | 1987-02-04 | 1987-02-04 | |
| US010,786 | 1987-02-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1988005911A1 true WO1988005911A1 (en) | 1988-08-11 |
Family
ID=21747427
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US1988/000217 WO1988005911A1 (en) | 1987-02-04 | 1988-01-27 | Optical carbon monoxide sensors impregnated on porous monolithic substrates |
Country Status (1)
| Country | Link |
|---|---|
| WO (1) | WO1988005911A1 (en) |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0617275A1 (en) * | 1993-03-24 | 1994-09-28 | Eurodif Production | Detector for acid gases or uranium hexafluoride |
| US5486336A (en) * | 1990-06-12 | 1996-01-23 | Catalytica, Inc. | NOX sensor assembly |
| EP0699903A1 (en) * | 1994-09-05 | 1996-03-06 | Japan Pionics Co., Ltd. | Reagent for detecting gaseous hydrides |
| EP0746755A1 (en) * | 1993-01-26 | 1996-12-11 | Fci-Fiberchem, Inc. | A solid state sensor for carbon monoxide |
| EP0779975A1 (en) * | 1994-08-29 | 1997-06-25 | Quantum Group Inc. | Photon absorbing bioderived organometallic carbon monoxide sensors |
| EP0884590A1 (en) * | 1997-06-12 | 1998-12-16 | Quantum Group | Carbon monoxide sensors with controlled response threshold |
| EP0901009A2 (en) * | 1997-08-29 | 1999-03-10 | Nippon Telegraph and Telephone Corporation | Nitrogen dioxide gas sensing method, nitrogen dioxide gas sensing element, and nitrogen dioxide gas sensor using the same |
| US8956571B2 (en) | 2006-04-13 | 2015-02-17 | Quantum Group Inc. | Carbon monoxide sensor system and related methods |
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| US3672845A (en) * | 1970-07-28 | 1972-06-27 | Miles Lab | Test device for albumin |
| US4043934A (en) * | 1974-07-24 | 1977-08-23 | The Regents Of The University Of California | Catalyst and method for oxidizing reducing gases |
| US4351662A (en) * | 1981-06-25 | 1982-09-28 | Corning Glass Works | Method of making photosensitive porous glass |
-
1988
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| US3672845A (en) * | 1970-07-28 | 1972-06-27 | Miles Lab | Test device for albumin |
| US4043934A (en) * | 1974-07-24 | 1977-08-23 | The Regents Of The University Of California | Catalyst and method for oxidizing reducing gases |
| US4351662A (en) * | 1981-06-25 | 1982-09-28 | Corning Glass Works | Method of making photosensitive porous glass |
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| Title |
|---|
| Analytical Chemistry, Vol. 19, No. 2, published February 1947, SHEPHERD, "Rapid Determination of Small Amounts of Carbon Monoxide", see pages 77-81. * |
| Journal of Analytic Chemistry of the USSR, Vol. 40, No. 9, published September 1985, MESHKOVSKI et al., "Colorimetric Porous Indicator of Carbon Dioxide", pages 1285-1288. * |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5486336A (en) * | 1990-06-12 | 1996-01-23 | Catalytica, Inc. | NOX sensor assembly |
| EP0746755A4 (en) * | 1993-01-26 | 1997-11-12 | Fiberchem Inc | A solid state sensor for carbon monoxide |
| EP0746755A1 (en) * | 1993-01-26 | 1996-12-11 | Fci-Fiberchem, Inc. | A solid state sensor for carbon monoxide |
| FR2703158A1 (en) * | 1993-03-24 | 1994-09-30 | Eurodif Production | Hydrofluoric acid vapor detector. |
| EP0617275A1 (en) * | 1993-03-24 | 1994-09-28 | Eurodif Production | Detector for acid gases or uranium hexafluoride |
| EP0779975A4 (en) * | 1994-08-29 | 1997-12-29 | Quantum Group Inc | Photon absorbing bioderived organometallic carbon monoxide sensors |
| EP0779975A1 (en) * | 1994-08-29 | 1997-06-25 | Quantum Group Inc. | Photon absorbing bioderived organometallic carbon monoxide sensors |
| US5665313A (en) * | 1994-09-05 | 1997-09-09 | Japan Pionics Co., Ltd. | Detecting agent |
| EP0699903A1 (en) * | 1994-09-05 | 1996-03-06 | Japan Pionics Co., Ltd. | Reagent for detecting gaseous hydrides |
| EP0884590A1 (en) * | 1997-06-12 | 1998-12-16 | Quantum Group | Carbon monoxide sensors with controlled response threshold |
| EP0901009A2 (en) * | 1997-08-29 | 1999-03-10 | Nippon Telegraph and Telephone Corporation | Nitrogen dioxide gas sensing method, nitrogen dioxide gas sensing element, and nitrogen dioxide gas sensor using the same |
| EP0901009A3 (en) * | 1997-08-29 | 1999-04-14 | Nippon Telegraph and Telephone Corporation | Nitrogen dioxide gas sensing method, nitrogen dioxide gas sensing element, and nitrogen dioxide gas sensor using the same |
| US6362005B1 (en) | 1997-08-29 | 2002-03-26 | Nippon Telegraph And Telephone Corporation | Nitrogen dioxide gas sensing method, nitrogen dioxide gas sensor element, and nitrogen dioxide gas sensor using the same |
| US8956571B2 (en) | 2006-04-13 | 2015-02-17 | Quantum Group Inc. | Carbon monoxide sensor system and related methods |
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