US3934976A
Expired / Lapsed
US
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Trace lead analysis method
Assignee: Mobil Oil AS
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Filing: 1974-02-19
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Granted: 1976-01-27
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Expires: 1994-02-19
Abstract
Abstract The lead content of gasolines, particularly in concentrations of from 0.00 to 0.10 gram of lead per U.S. gallon of gasoline, is determined colorimetrically by mixing iodine and tetraorganoammonium halide solution with the gasoline, subjecting the mixture to ultraviolet light or heat, agiating the mixture with ammonium nitrate or nitric acid, passing the aqueous phase into 4-(2-pyridylazo)-resorcinol disodium and comparing the resulting color with a standard color scale or a colorimeter to determine the initial lead concentration.
Inventors
- 👤 Catherine A. Zelaskowski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 16:26
CPC Classifications
G; G01; G01N; G01N31/00; G01N31/22; G01N33/00; G01N33/26; G01N33/28; G01N33/2835; G01N33/2864
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
123 words
A method for colorimetrically determining the lead content in gasoline comprising (1) mixing a gasoline sample containing tetraalkyllead with iodine in the presence of a tetraorganoammonium halide and exposing the mixture to ultra-violet radiation from a 3660 A wavelength ultra-violet source for a period of from 30 seconds to about 10 minutes sufficient to convert the tetraalkyllead to dialkyllead diiodide, (2) mixing the resulting reaction mixture with an aqueous solution of an acidic compound selected from the group consisting of nitric acid and ammonium nitrate and separating the resulting aqueous phase from the organic gasoline phase, and (3) combining the aqueous phase with an alkali metal salt of 4-(2-pyridylazo)-resorcinol in an aqueous solution to produce a color corresponding to the initial lead concentration.
Claim 2
Independent Claim
123 words
A method for colorimetrically determining the lead content in gasoline comprising (1) mixing a gasoline sample containing tetraalkyllead with iodine in the presence of a tetraorganoammonium halide and exposing the mixture to ultra-violet radiation from a 3660 A wavelength ultra-violet source for a period of from 30 seconds to about 10 minutes sufficient to convert the tetraalkyllead to dialkyllead diiodide, (2) mixing the resulting reaction mixture with an aqueous solution of an acidic compound selected from the group consisting of nitric acid and ammonium nitrate and separating the resulting aqueous phase from the organic gasoline phase, and (3) combining the aqueous phase with an alkali metal salt of 4-(2-pyridylazo)-resorcinol in an aqueous solution to produce a color corresponding to the initial lead concentration.
Claim 3
Dependent Claim
47 words
The method of claim 1 wherein the separation of the aqueous phase in Step 2 is carried out by filtering the combined aqueous and organic phases, whereby the aqueous phase passes through the filter first and directly into the said aqueous solution containing the alkali metal salt.
Claim 4
Dependent Claim
14 words
The method of claim 1 wherein the said alkali metal salt is disodium 4-(2-pyridylazo)-resorcinol.
Claim 5
Dependent Claim
42 words
The method of claim 1 wherein the tetraorganoammonium halide has the formula ##EQU2## wherein the R groups are individually selected from the group consisting of alkyl, aryl, aralkyl and alkaryl of from 1 to 20 carbon atoms and X is a halide.
Claim 6
Dependent Claim
11 words
The method of claim 4 wherein the R groups are alkyl.
Claim 7
Dependent Claim
16 words
The method of claim 5 wherein the four R groups are ethyl and X is chlorine.
Claim 8
Dependent Claim
13 words
The method of claim 1 wherein the tetraorganoammonium halide is methyltricaprylyl ammonium chloride.
Claim 9
Independent Claim
136 words
A method for colorimetrically determining the lead content in gasoline comprising (1) mixing a gasoline sample containing from 0 to over 0.10 grams of a tetraalkyllead compound per gallon of gasoline with iodine in the presence of a tetraorganoammonium halide and exposing the mixture to ultra-violet radiation from a 3660 A wavelength ultra-violet source for a period of from 30 seconds to about 10 minutes sufficient to convert the tetraalkyllead to dialkyllead diiodide, (2) mixing the resulting reaction mixture with an aqueous solution of an acidic compound selected from the group consisting of nitric acid and ammonium nitrate and separating the resulting aqueous phase from the organic gasoline phase, and (3) combining the aqueous phase with an alkali metal salt of 4-(2-pyridylazo)-resorcinol in an aqueous solution to produce a color corresponding to the initial lead concentration.
Claim 10
Independent Claim
136 words
A method for colorimetrically determining the lead content in gasoline comprising (1) mixing a gasoline sample containing from 0 to over 0.10 grams of a tetraalkyllead compound per gallon of gasoline with iodine in the presence of a tetraorganoammonium halide and exposing the mixture to ultra-violet radiation from a 3660 A wavelength ultra-violet source for a period of from 30 seconds to about 10 minutes sufficient to convert the tetraalkyllead to dialkyllead diiodide, (2) mixing the resulting reaction mixture with an aqueous solution of an acidic compound selected from the group consisting of nitric acid and ammonium nitrate and separating the resulting aqueous phase from the organic gasoline phase, and (3) combining the aqueous phase with an alkali metal salt of 4-(2-pyridylazo)-resorcinol in an aqueous solution to produce a color corresponding to the initial lead concentration.
Claim 11
Dependent Claim
29 words
The method of claim 8 wherein the tetraalkyllead compounds are derived from lead alkyl formulations for gasoline selected from the group consisting of tetramethyllead, tetraethyllead, trimethylethyllead, dimethyldiethyllead and methyltriethyllead.
References Cited (Backward Citations)
US3806319A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-01-26 | 1979-07-28 | 1980-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-26 | 1983-07-28 | 1984-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-26 | 1987-07-28 | 1988-01-27 | $7700.00 | Window Closed / Lapsed |