US4873197A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Quick color test to detect lead release from glazed ceramic and enameled metal ware
Assignee: United States Department of Health and Human Services
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Filing: 1988-10-28
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Granted: 1989-10-10
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Expires: 2008-10-28
Abstract
Abstract A color test is presented for the purpose of quickly identifying glazed ceramic and/or enameled metal ware which releases excessive Pb. Citric acid solution on filter paper is used to extract Pb from the ware and a Pb sensitive chromogen indicates the presence of Pb on the paper. The quick color test takes approximately 30 minutes and is useful for screening ware for testing by the 24 hour AOAC/ASTM method.
Inventors
- 👤 John H. Gould
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 16:50
CPC Classifications
G; G01; G01N; G01N31/00; G01N31/22; Y; Y10; Y10T; Y10T436/00; Y10T436/25; Y10T436/25375; Y10T436/255
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
75 words
A method for determining the presence of excessive amounts of lead on an area of glazed ceramic or enameld metal ware, which comprises: extracting lead from said area of said ware by contacting said area with a filter paper containing a solution of a material selected from the group consisting of formic acid, citric acid, and mixtures thereof; spotting said filter paper with a chromogen; and detecting a change in color of said filter paper.
Claim 2
Independent Claim
75 words
A method for determining the presence of excessive amounts of lead on an area of glazed ceramic or enameld metal ware, which comprises: extracting lead from said area of said ware by contacting said area with a filter paper containing a solution of a material selected from the group consisting of formic acid, citric acid, and mixtures thereof; spotting said filter paper with a chromogen; and detecting a change in color of said filter paper.
Claim 3
Dependent Claim
33 words
The method of claim 1, which further comprises subjecting any said ware, wherein a positive spot test is indicated, to a full scale leaching procedure to quantitate the amount of lead therein procedure.
Claim 4
Dependent Claim
25 words
The method of claim 1, wherein said filter paper is spotted with said chromogen about thirty minutes after said filter paper has contacted said ware.
Claim 5
Dependent Claim
25 words
The method of claim 1, wherein said filter paper is spotted with said chromogen about ten minutes after said filter paper has contacted said ware.
Claim 6
Dependent Claim
15 words
The method of claim 1, wherein said filter paper contains a solution of citric acid.
Claim 7
Dependent Claim
22 words
The method of claim 5, wherein said citric acid is at a concentration of about 4% volume to weight as monobasic acid.
Claim 8
Dependent Claim
25 words
The method of claim 5, wherein said citric acid is at a concentration of about 3% to about 5% volume to weight as monobasic acid.
Claim 9
Dependent Claim
15 words
The method of claim 1, wherein said filter paper contains a solution of formic acid.
Claim 10
Dependent Claim
26 words
The method of claim 8, wherein said formic acid is at a concentration of about 4% volume to weight or volume to volume as monobasic acid.
Claim 11
Dependent Claim
29 words
The method of claim 8, wherein said formic acid is at a concentration of about 3% to about 5% volume to weight or volume to volume as monobasic acid.
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) | 1992-10-09 | 1993-04-10 | 1993-10-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-10-09 | 1997-04-10 | 1997-10-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-10-09 | 2001-04-10 | 2001-10-10 | $7700.00 | Window Closed / Lapsed |