US4511658A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Colorimetric detector for formaldehyde vapor
Assignee: Kansas State University
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Filing: 1983-02-28
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Granted: 1985-04-16
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Expires: 2003-02-28
Abstract
Abstract A sensitive colorimetric detector for formaldehyde vapor is prepared by applying a ketone solution of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT) to a support coated with a stable metal bicarbonate to form a compound from which the ketone can be displaced by formaldehyde to yield a chromogen developing a purple color proportional to the amount of formaldehyde. The detector is sensitive to gaseous formaldehyde in air at concentrations below 2 ppm.
Inventors
- 👤 Jack L. Lambert
- 👤 Yuan C. Chiang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 00:44
CPC Classifications
G; G01; G01N; G01N31/00; G01N31/22; Y; Y10; Y10T; Y10T436/00; Y10T436/20; Y10T436/200833; Y10T436/202499
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
84 words
The process of preparing a colorimetric detector for formaldehyde vapor, comprising: (a) coating an inert solid support with a solid phase layer of stable metal bicarbonate; (b) applying to said metal bicarbonate layer a solution of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT) in a volatile liquid ketone forming a compound with AHMT from which the ketone can be displaced by formaldehyde; and (c) evaporating unreacted ketone from said layer and support to obtain a colorimetric detector sensitive to formaldehyde vapor in the detective range below 2 ppm formaldehyde.
Claim 2
Dependent Claim
84 words
The process of preparing a colorimetric detector for formaldehyde vapor, comprising: (a) coating an inert solid support with a solid phase layer of stable metal bicarbonate; (b) applying to said metal bicarbonate layer a solution of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT) in a volatile liquid ketone forming a compound with AHMT from which the ketone can be displaced by formaldehyde; and (c) evaporating unreacted ketone from said layer and support to obtain a colorimetric detector sensitive to formaldehyde vapor in the detective range below 2 ppm formaldehyde.
Claim 3
Dependent Claim
10 words
The colorimetric detector prepared by the process of claim 1.
Claim 4
Dependent Claim
21 words
The process of claim 1 in which said metal bicarbonate is selected from the class consisting of sodium and potassium bicarbonate.
Claim 5
Dependent Claim
20 words
The process of claim 1 in which said ketone is selected from the class consisting of acetone and methylethyl ketone.
Claim 6
Dependent Claim
107 words
The process of preparing a colorimetric detector for formaldehyde vapor, comprising: (a) coating an inert solid support with a solid phase layer of a bicarbonate salt selected from the class consisting of sodium and potassium bicarbonate; (b) applying to said metal bicarbonate layer a solution of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT) in a volatile liquid ketone forming a compound with AHMT from which the ketone can be displaced by formaldehyde, said ketone being selected from the class consisting of acetone and methylethyl ketone; and (c) evaporating unreacted ketone from said layer and support to obtain a colorimetric detector sensitive to formaldehyde vapor in the detective range below 2 ppm formaldehyde.
Claim 7
Dependent Claim
107 words
The process of preparing a colorimetric detector for formaldehyde vapor, comprising: (a) coating an inert solid support with a solid phase layer of a bicarbonate salt selected from the class consisting of sodium and potassium bicarbonate; (b) applying to said metal bicarbonate layer a solution of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT) in a volatile liquid ketone forming a compound with AHMT from which the ketone can be displaced by formaldehyde, said ketone being selected from the class consisting of acetone and methylethyl ketone; and (c) evaporating unreacted ketone from said layer and support to obtain a colorimetric detector sensitive to formaldehyde vapor in the detective range below 2 ppm formaldehyde.
Claim 8
Dependent Claim
10 words
The colorimetric detector prepared by the process of claim 5.
Claim 9
Dependent Claim
81 words
The process of preparing a colorimetric detector for formaldehyde vapor, comprising: (a) coating an inert solid support with a solid phase layer of sodium bicarbonate; (b) applying to said bicarbonate layer an acetone solution of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT) to form an acetone aminal compound with said AHMT from which acetone can be displaced by formaldehyde; and (c) evaporating unreacted acetone from said layer and support to obtain a colorimetric detector sensitive to formaldehyde vapor in the detective range below 2 ppm formaldehyde.
Claim 10
Dependent Claim
81 words
The process of preparing a colorimetric detector for formaldehyde vapor, comprising: (a) coating an inert solid support with a solid phase layer of sodium bicarbonate; (b) applying to said bicarbonate layer an acetone solution of 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT) to form an acetone aminal compound with said AHMT from which acetone can be displaced by formaldehyde; and (c) evaporating unreacted acetone from said layer and support to obtain a colorimetric detector sensitive to formaldehyde vapor in the detective range below 2 ppm formaldehyde.
Claim 11
Dependent Claim
10 words
The colorimetric detector prepared by the process of claim 7.
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) | 1988-04-15 | 1988-10-15 | 1989-04-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-15 | 1992-10-15 | 1993-04-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-15 | 1996-10-15 | 1997-04-16 | $7700.00 | Window Closed / Lapsed |