US4666859A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reagent for colorimetrically indicating the presence of formaldehyde
Assignee: SENSIDYNE Inc A FLORIDA Corp
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Filing: 1986-05-19
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Granted: 1987-05-19
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Expires: 2006-05-19
Abstract
Abstract A novel colorimetric reagent for the selective determination of formaldehyde in solution or in air is described. The reagent comprises at least two chemicals: rubeanic acid or a rubeanic acid derivative, and a cyano complex of a metal. Upon addition of formaldehyde, a color is formed which is quantitatively related to the number of formaldehyde molecules reacted. The chromophoric reagent can be mixed with other inactive ingredients such as stabilizers, buffers, polymers, etc. and used in solutions as a coating on a flat surface, or on beads to detect and determine formaldehyde colorimetrically. One particular application of the colorimetric reagent is in a direct reading colorimetric gas dosimeter for formaldehyde.
Inventors
- 👤 Amir J. Attar
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 22:48
CPC Classifications
G; G01; G01N; G01N31/00; G01N31/22; Y; Y10; Y10S; Y10S436/00; Y10S436/902; Y10T; Y10T436/00; Y10T436/20; Y10T436/200833; Y10T436/202499
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
39 words
A chromophoric reagent for colorimetrically indicating the presence of formaldehyde comprising rubeanic acid or a derivative of rubeanic acid and a metal-cyanide complex being present in an amount effective to produce a color change in the presence of formaldehyde.
Claim 2
Dependent Claim
39 words
A chromophoric reagent for colorimetrically indicating the presence of formaldehyde comprising rubeanic acid or a derivative of rubeanic acid and a metal-cyanide complex being present in an amount effective to produce a color change in the presence of formaldehyde.
Claim 3
Dependent Claim
24 words
A chromophoric reagent according to claim 1 in the form of a solution of said rubeanic acid and said metal-cyanide complex in a solvent.
Claim 4
Dependent Claim
26 words
A chromophoric reagent according to claim 1 wherein said rubeanic acid and said metal-cyanide complex are in the form of a dried coating on a substrate.
Claim 5
Dependent Claim
38 words
A chromophoric reagent according to claim 1 wherein said metal-cyanide complex comprises a cyano complex of a metal selected from the group consisting of silver, copper, cadmium, lead, iron, bismuth, cobalt, thallium, nickel, gold, palladium, platinum and ruthenium.
Claim 6
Dependent Claim
35 words
A chromophoric reagent according to claim 1 wherein said rubeanic acid or said derivative, is a compound selected from the group consisting of N,N' dialkyl rubeanic acid, N,N' dihydroxyalkyl rubeanic acid, and N,N' diarylrubeanic acid.
Claim 7
Dependent Claim
15 words
A chromophoric reagent according to claim 1 wherein said metal-cyanide complex comprises potassium silver cyanide.
Claim 8
Dependent Claim
50 words
A chromophoric reagent for colorimetrically indicating the presence of formaldehyde comprising rubeanic acid or a derivative of rubeanic acid, potassium silver cyanide and, potassium cyanide, being present in an amount effective to produce a color change in the presence of formaldehydre, said reagent further comprising potassium nitrate and potassium borate.
Claim 9
Dependent Claim
50 words
A chromophoric reagent for colorimetrically indicating the presence of formaldehyde comprising rubeanic acid or a derivative of rubeanic acid, potassium silver cyanide and, potassium cyanide, being present in an amount effective to produce a color change in the presence of formaldehydre, said reagent further comprising potassium nitrate and potassium borate.
Claim 10
Dependent Claim
39 words
In a gas dosimeter including a reagent for colorimetrically indicating the presence of formaldehyde, the improvement wherein said reagent comprises an effective amount of rubeanic acid or a derivative of rubeanic acid and an effective concentration of metal-cyanide complex.
Claim 11
Dependent Claim
39 words
In a gas dosimeter including a reagent for colorimetrically indicating the presence of formaldehyde, the improvement wherein said reagent comprises an effective amount of rubeanic acid or a derivative of rubeanic acid and an effective concentration of metal-cyanide complex.
Claim 12
Dependent Claim
38 words
A gas dosimeter according to claim 8 wherein said metal-cyanide complex comprises a cyano complex of a metal selected from the group consisting of silver, copper, cadmium, lead, iron, bismuth, cobalt, thallium, nickel, gold, palladium, platinum, and ruthenium.
Claim 13
Dependent Claim
15 words
A gas dosimeter according to claim 8 wherein said metal-cyanide complex comprises potassium silver cyanide.
Claim 14
Dependent Claim
71 words
A gas dosimeter for colorimetrically indicating the presence of formaldehyde, said dosimeter comprising a housing having an opening therein through which ambient gas may pass, a carrier layer disposed within said housing, and a chromophoric reagent which changes color in response to exposure to formaldehyde carried by said carrier, said chromophoric reagent comprising an effective amount of rubeanic acid or a rubeanic acid derivative and an effective concentration of metal-cyanide complex.
Claim 15
Dependent Claim
71 words
A gas dosimeter for colorimetrically indicating the presence of formaldehyde, said dosimeter comprising a housing having an opening therein through which ambient gas may pass, a carrier layer disposed within said housing, and a chromophoric reagent which changes color in response to exposure to formaldehyde carried by said carrier, said chromophoric reagent comprising an effective amount of rubeanic acid or a rubeanic acid derivative and an effective concentration of metal-cyanide complex.
Claim 16
Independent Claim
48 words
A method for colorimetrically indicating the presence of formaldehyde which comprises a fluid containing formaldehyde exposing a chromophoric reagent comprising an effective amount of rubeanic acid or a rubeanic acid derivative and an effective concentration of a metal-cyanide complex, and observing the change in color of said reagent.
Claim 17
Independent Claim
48 words
A method for colorimetrically indicating the presence of formaldehyde which comprises a fluid containing formaldehyde exposing a chromophoric reagent comprising an effective amount of rubeanic acid or a rubeanic acid derivative and an effective concentration of a metal-cyanide complex, and observing the change in color of said reagent.
Claim 18
Dependent Claim
12 words
A method according to claim 12 wherein said fluid is formaldehyde vapors.
Claim 19
Dependent Claim
15 words
A method according to claim 12 wherein said fluid is an aqueous solution of formaldehyde.
Claim 20
Dependent Claim
37 words
A method according to claim 12 wherein said metal-cyanide complex comprises a cyano complex of a metal selected from the group consisting of silver, copper, cadmium, lead, iron, bismuth, cobalt, thallium, nickel, gold, palladium, platinum, and ruthenium.
Claim 21
Dependent Claim
14 words
A method according to claim 15 wherein said metal-cyanide complex comprises potassium silver cyanide.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-05-18 | 1990-11-17 | 1991-05-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-05-18 | 1994-11-17 | 1995-05-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-05-18 | 1998-11-17 | 1999-05-19 | $7700.00 | Window Closed / Lapsed |