US4566949A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of operating a self cleaning electrochemical detector
Assignee: HP Inc
•
Filing: 1984-10-11
•
Granted: 1986-01-28
•
Expires: 2004-10-11
Abstract
Abstract An improved electrochemical cell and detector which is especially suited for analysis of rapidly changing flowing streams such as found in high performance liquid chromatography is disclosed. A uniquely designed jet made of microbore drawn capillary tubing permits the construction of a cell for very low flow rates that still retains true wall-jet hydrodynamics. The invention prevents changes in cell response in time by periodically cleaning a working electrode in a novel way. Cleaning and detection are both accomplished on a time scale much shorter than the fastest liquid chromatograph peaks by means of a unique three electrode cell design utilizing a small diameter, low capacitance, metal working electrode situated close to a reference electrode. Cleaning is accomplished by means of a nonsquare wave periodic waveform which is effective in cleaning a wide variety of contaminants through the oxidation and reduction of the working electrode and/or solvent prior to application of one or more working potentials while providing a stable, reproducible detector. The detector thus provides improvements in both sensitivity and bandwidth over the prior art.
Inventors
- 👤 Terry A. Berger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 07:39
CPC Classifications
G; G01; G01N; G01N30/00; G01N30/02; G01N30/62; G01N30/64; G01N27/00; G01N27/26; G01N27/28; G01N27/30; G01N27/38
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
92 words
A method of detecting the concentration of electrochemical species in a fluid with an electrochemical cell with a working electrode comprising: oxidizing the working electrode for a period less than or equal to 200 milliseconds; reducing the working electrode for a period less than or equal to 200 milliseconds; applying a working potential to the working electrode for a period less than or equal to 800 milliseconds; and measuring a current produced by electrochemical reactions on the working electrode at the working potential for integer multiples of a main power line period.
Claim 2
Independent Claim
92 words
A method of detecting the concentration of electrochemical species in a fluid with an electrochemical cell with a working electrode comprising: oxidizing the working electrode for a period less than or equal to 200 milliseconds; reducing the working electrode for a period less than or equal to 200 milliseconds; applying a working potential to the working electrode for a period less than or equal to 800 milliseconds; and measuring a current produced by electrochemical reactions on the working electrode at the working potential for integer multiples of a main power line period.
Claim 3
Dependent Claim
15 words
A method as in claim 1 further comprising: flowing the fluid through the electrochemical cell.
Claim 4
Dependent Claim
31 words
A method as in claim 1 further comprising applying a plurality of working potentials to the working electrode for a plurality of periods each less than or equal to 800 milliseconds.
Claim 5
Independent Claim
111 words
A method of detecting the concentration of electrochemical species in a fluid with an electrochemical cell with a working electrode comprising a metal, said method comprising: oxidizing the working electrode for a first period less than or equal to 200 milliseconds so that the surface area of the working electrode increases; reducing the working electrode for a second period less than or equal to 200 milliseconds so that the surface area of the working electrode decreases; applying a working potential to the working electrode for a third period less than or equal to 800 milliseconds, and measuring a current produced by electrochemical reactions on the working electrode at the working potential.
Claim 6
Independent Claim
111 words
A method of detecting the concentration of electrochemical species in a fluid with an electrochemical cell with a working electrode comprising a metal, said method comprising: oxidizing the working electrode for a first period less than or equal to 200 milliseconds so that the surface area of the working electrode increases; reducing the working electrode for a second period less than or equal to 200 milliseconds so that the surface area of the working electrode decreases; applying a working potential to the working electrode for a third period less than or equal to 800 milliseconds, and measuring a current produced by electrochemical reactions on the working electrode at the working potential.
Claim 7
Dependent Claim
31 words
A method as in claim 4 further comprising applying a plurality of working potentials to the working electrode for a plurality of periods each less than or equal to 800 milliseconds.
Claim 8
Dependent Claim
17 words
A method as in claim 4 wherein the first and second periods are applied in reverse order.
Claim 9
Dependent Claim
15 words
A method as in claim 4 further comprising flowing the fluid through the electrochemical cell.
Claim 10
Dependent Claim
40 words
A method as in claim 4 comprising: further oxidizing the fluid during the first period to produce oxygen bubbles on the working electrode; and further reducing the fluid during the second period to produce hydrogen bubbles on the working electrode.
Claim 11
Dependent Claim
31 words
A method as in claim 8 further comprising applying a plurality of working potentials to the working electrode for a plurality of periods each less than or equal to 800 milliseconds.
Claim 12
Dependent Claim
17 words
A method as in claim 8 wherein the first and second periods are applied in reverse order.
Claim 13
Dependent Claim
15 words
A method as in claim 8 further comprising flowing the fluid through the electrochemical cell.
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) | 1989-01-27 | 1989-07-29 | 1990-01-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-01-27 | 1993-07-29 | 1994-01-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-01-27 | 1997-07-29 | 1998-01-28 | $7700.00 | Window Closed / Lapsed |