US4920057A
Expired / Lapsed
US
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Method for colorimetric analysis of metals
Assignee: Chemetrics Inc
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Filing: 1989-06-02
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Granted: 1990-04-24
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Expires: 2009-06-02
Abstract
Abstract A portable test kit for colorimetric analysis of trace levels of dithizone-complexing metal cations including lead, is provided. The test kit includes storage tubes each of which contains the reagents and apparatus required for a single test, and has sufficient volumetric capacity to serve as a vessel for the formation and extraction of colored, metal cation-dithizonate complex. Use of the test kit involves a novel and unique sampling technique for capturing a portion of a colored liquid within a container for viewing of the color. Also provided is an improved method for analyzing for trace levels of such metal cations.
Inventors
- 👤 Henry B. Castaneda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:09
CPC Classifications
G; G01; G01N; G01N1/00; G01N1/28; G01N1/40; G01N1/405; B; B01; B01L; B01L3/00; B01L3/50; B01L3/508; B01L3/5082; G01N31/00; G01N31/22; G01N33/00; G01N33/18; Y; Y10; Y10T; Y10T436/00; Y10T436/25; Y10T436/25375; Y10T436/255
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
108 words
A colorimetric method useful in the field for the analysis of trace levels of a dithizonate-complexing metal cation in an aqueous sample, said method comprising extracting said metal cation from a relatively larger volume of an aqueous sample, into a relatively smaller volume by use of an organic extractant for an extractable, metal cation-dithizonate complex, of greater density than water; allowing the resulting biphasic mixture to separate into an upper aqueous layer and a colored, lower layer of organic liquid; while maintaining positive pressure in a hollow tubular body, passing an open end of said hollow tubular body through said upper aqueous layer into said lower organic layer;
Claim 2
Dependent Claim
108 words
A colorimetric method useful in the field for the analysis of trace levels of a dithizonate-complexing metal cation in an aqueous sample, said method comprising extracting said metal cation from a relatively larger volume of an aqueous sample, into a relatively smaller volume by use of an organic extractant for an extractable, metal cation-dithizonate complex, of greater density than water; allowing the resulting biphasic mixture to separate into an upper aqueous layer and a colored, lower layer of organic liquid; while maintaining positive pressure in a hollow tubular body, passing an open end of said hollow tubular body through said upper aqueous layer into said lower organic layer;
Claim 3
Dependent Claim
26 words
The colorimetric method of claim 1, wherein said container has a length, and wherein said analyzing comprises viewing lengthwise through said organic liquid within said container.
Claim 4
Dependent Claim
13 words
The colorimetric method of claim 1, wherein said dithizonate-complexing metal cation is lead.
References Cited (Backward Citations)
US3634038A
Cited
US3912454A
Cited
US3980436A
Cited
US4125376A
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GB1542411A
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US4409182A
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US4332769A
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US4537747A
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US4770853A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-04-23 | 1993-10-23 | 1994-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-23 | 1997-10-23 | 1998-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-23 | 2001-10-23 | 2002-04-24 | $7700.00 | Window Closed / Lapsed |