US3893808A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and paper test strip for determining low levels of lead in hydrocarbon fuels
Assignee: Standard Oil Co
•
Filing: 1974-09-20
•
Granted: 1975-07-08
•
Expires: 1994-09-20
Abstract
Abstract Test method suitable for field testing for lead contamination in unleaded motor fuels, and chemically-treated paper test strip utilized in the testing procedure. The test method comprises contacting a sample of motor fuel with a strip of paper that has been pre-treated in separate zones with a solution of iodine and a solution of a mixture of iodine and potassium iodide. The organic lead compound present in the sample is then identified by the appearance of a red coloration on the paper test strip with the application of a few drops of dithizone indicator solution to the paper.
Inventors
- 👤 Ralph L Campbell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:00
CPC Classifications
G; G01; G01N; G01N31/00; G01N31/22
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
176 words
IN A METHOD FOR DETERMINING THE PRESENCE OF ORGANIC LEAD COMPOUNDS IN HYDROCARBON FUELS WHEREIN THE ORGANIC LEAD IS REACHED WITH IODINE FORM LEAD IODIDE AND THE LEAD IODINE IS SUBSEQUENTLY REACTED WITH DITHIZONE TO FORM A COLORED LEAD DITHIZONATE WHEN EXTRACTED INTO AN ORGANIC SOLVENT THE IMPROVEMENT COMPRISING: CONTACTING SAID ORGANIC LEAD-CONTAINING HYDROCARBON FUEL WITH A STRIP OF CHEMICALLY TREATED PAPER, SAID PAPER STRIP HAVING AT LEAST THREE DISTINCT SEPARATE ZONES, A THROUGH C, WHEREIN ZONE A IS TREATED WITH IODINE, ZONE B IS TREATED WITH A MIXTURE OF IODINE AND POTASSIUM IODINE, AND ZONE C IS AN UNTREATED AREA ADJACENT TO ZONE B, WHEREON CONTACTING SAID HYDROCARBON FUEL WITH THE PAPER TEST STRIP. THE ORGANIC LEAD COMPOUNDS IN THE FUEL BY MEANS OF CAPILLARY ACTION ARE REACTED IN SEQUENCE AT ZONE A AND THEN AT ZONE B TO FORM LEAD IODIDE, AND THE LEAD IODIDE THUSLY FORMED IS CONVERTED TO CHARACTERISTICALLY COLORED LEAD DITHIZONATE IN ZONE C OF THE PAPER STRIP BY APPLYING TO ZONE C A SOLUTION OF DITHIZONE IN AN ORGANIC SOLVENT.
Claim 2
Dependent Claim
176 words
IN A METHOD FOR DETERMINING THE PRESENCE OF ORGANIC LEAD COMPOUNDS IN HYDROCARBON FUELS WHEREIN THE ORGANIC LEAD IS REACHED WITH IODINE FORM LEAD IODIDE AND THE LEAD IODINE IS SUBSEQUENTLY REACTED WITH DITHIZONE TO FORM A COLORED LEAD DITHIZONATE WHEN EXTRACTED INTO AN ORGANIC SOLVENT THE IMPROVEMENT COMPRISING: CONTACTING SAID ORGANIC LEAD-CONTAINING HYDROCARBON FUEL WITH A STRIP OF CHEMICALLY TREATED PAPER, SAID PAPER STRIP HAVING AT LEAST THREE DISTINCT SEPARATE ZONES, A THROUGH C, WHEREIN ZONE A IS TREATED WITH IODINE, ZONE B IS TREATED WITH A MIXTURE OF IODINE AND POTASSIUM IODINE, AND ZONE C IS AN UNTREATED AREA ADJACENT TO ZONE B, WHEREON CONTACTING SAID HYDROCARBON FUEL WITH THE PAPER TEST STRIP. THE ORGANIC LEAD COMPOUNDS IN THE FUEL BY MEANS OF CAPILLARY ACTION ARE REACTED IN SEQUENCE AT ZONE A AND THEN AT ZONE B TO FORM LEAD IODIDE, AND THE LEAD IODIDE THUSLY FORMED IS CONVERTED TO CHARACTERISTICALLY COLORED LEAD DITHIZONATE IN ZONE C OF THE PAPER STRIP BY APPLYING TO ZONE C A SOLUTION OF DITHIZONE IN AN ORGANIC SOLVENT.
Claim 3
Dependent Claim
19 words
The method in claim 1 wherein the organic lead compound is present in the hydrocarbon fuel as lead alkyl.
Claim 4
Dependent Claim
14 words
The method in claim 2 wherein the paper test strip is composed of cellulose.
Claim 5
Dependent Claim
21 words
The method in claim 3 wherein the test procedure is carried out in the presence of light containing some ultraviolet light.
Claim 6
Dependent Claim
22 words
The method in claim 4 wherein the iodine in Zone A is applied to the paper strip as a solution in alcohol.
Claim 7
Dependent Claim
10 words
The method in claim 5 wherein the alcohol is methanol.
Claim 8
Dependent Claim
29 words
The method in claim 6 wherein the iodine-potassium iodide mixture in Zone B is applied to the paper test strip as an aqueous solution of iodine and potassium iodide.
Claim 9
Dependent Claim
24 words
The method in claim 7 wherein the dithizone indicator is applied to the paper test strip as a solution in a halogenated hydrocarbon solvent.
Claim 10
Dependent Claim
12 words
The method in claim 8 wherein the halogenated hydrocarbon solvent is chloroform.
Claim 11
Dependent Claim
21 words
The method in claim 9 wherein the paper test strip has a second untreated zone positioned between Zones A and B.
Claim 12
Dependent Claim
19 words
The method in claim 9 wherein the paper test strip has a second untreated zone adjacent to Zone A.
Claim 13
Dependent Claim
21 words
The method in claim 10 wherein the paper test strip has a third untreated zone positioned between zones A and B.
Claim 14
Dependent Claim
69 words
A paper test strip for use in determining the presence of organic lead compounds in hydrocarbon fuels as lead dithizonate, said paper strip comprising a chemically treated paper having at least three distinct separate zones, A through C, and wherein: Zone A is treated with iodine; Zone B is treated with a mixture of iodine and potassium iodide; and Zone C is an untreated area adjacent to Zone B.
Claim 15
Dependent Claim
69 words
A paper test strip for use in determining the presence of organic lead compounds in hydrocarbon fuels as lead dithizonate, said paper strip comprising a chemically treated paper having at least three distinct separate zones, A through C, and wherein: Zone A is treated with iodine; Zone B is treated with a mixture of iodine and potassium iodide; and Zone C is an untreated area adjacent to Zone B.
Claim 16
Dependent Claim
14 words
The paper test strip in claim 13 wherein the paper is composed of cellulose.
Claim 17
Dependent Claim
19 words
The paper test strip in claim 13 wherein a second untreated zone is positioned between Zones A and B.
Claim 18
Dependent Claim
18 words
The paper test strip in claim 13 wherein a second untreated zone is positioned adjacent to Zone A.
Claim 19
Dependent Claim
19 words
The paper test strip in claim 16 wherein a third untreated zone is positioned between zones A and B.
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) | 1978-07-07 | 1979-01-06 | 1979-07-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-07 | 1983-01-06 | 1983-07-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-07 | 1987-01-06 | 1987-07-08 | $7700.00 | Window Closed / Lapsed |