Patent US5664681A successfully refreshed from Google Patents.
Patent US4920057A successfully refreshed from Google Patents.
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 17:24
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
Cited
GB1542411A
Cited
US4409182A
Cited
US4332769A
Cited
US4537747A
Cited
US4770853A
Cited
US4786604A
Cited
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 |