EP0418404A1
Expired / Lapsed
EP
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Method of determining optimum operating conditions in an electrochemical detector and electrochemical detector using the method
Assignee: Hewlett Packard GmbH Germany
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Filing: 1989-09-15
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Granted: —
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Expires: 2009-09-15
Abstract
Abstract A method of determining optimum operating potential in an electrochemical detector and an electrochemical detector (20) for performing the method, particularly for use in connection with a liquid chromatograph (21), are disclosed. A control and data processing unit (34) causes a plurality of different potentials to be successively applied in an electrochemical cell (11) and a subsequent electrochemical detection of the sample to be performed at each of the potentials. After each adjustment of a new potential, the current behaviour at the working electrode in the electrochemical cell (11) is monitored by an amperometer (31). When the current behaviour has stabilized, a trigger signal (26) is produced by the unit (34) which effects an injection of the sample into the separation column (25) of the chromatograph. From the current signals at the working electrode obtained for the different potentials, it can be determined which potential gives optimum detectability of the sample.
Inventors
- 👤 Thomas Dörr
- 👤 Clemens Linowski
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 10:03
CPC Classifications
G; G01; G01N; G01N30/00; G01N30/02; G01N30/62; G01N30/64; G01N27/00; G01N27/26; G01N27/416; G01N27/4163; G01N27/49; G01N2030/626; G01N2030/645
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
153 words
A method of determining optimum operating conditions in an electrochemical detector (20), wherein liquid including an electroactive sample to be detected is introduced into an electrochemical cell (11) of the detector (20) and wherein a potential (U in ) is applied between the liquid in the cell and a working electrode (1) such that a current is created at the working electrode (1), characterized in that a) a plurality of potentials (Pot1,Pot2,Pot3) is successively applied in the cell (11), with the values of said potentials corresponding to a sequence of discrete values ranging from an initial to a final value, b) after each adjustment of a new potential value, the sample is electrochemically detected in response to a trigger signal indicative of a stabilization of the working electrode current, and c) optimum operating potential for detection of the sample is determined from the plurality of detection results obtained according to step b) .
Claim 2
Independent Claim
153 words
A method of determining optimum operating conditions in an electrochemical detector (20), wherein liquid including an electroactive sample to be detected is introduced into an electrochemical cell (11) of the detector (20) and wherein a potential (U in ) is applied between the liquid in the cell and a working electrode (1) such that a current is created at the working electrode (1), characterized in that a) a plurality of potentials (Pot1,Pot2,Pot3) is successively applied in the cell (11), with the values of said potentials corresponding to a sequence of discrete values ranging from an initial to a final value, b) after each adjustment of a new potential value, the sample is electrochemically detected in response to a trigger signal indicative of a stabilization of the working electrode current, and c) optimum operating potential for detection of the sample is determined from the plurality of detection results obtained according to step b) .
Claim 3
Dependent Claim
24 words
A method as in claim 1 wherein the electrochemical detection of the sample (step b)) is repeated several times at each adjusted potential value.
Claim 4
Dependent Claim
26 words
A method as in claim 1 or 2, wherein the trigger signal is produced a predetermined time interval after the adjustment of a new potential value.
Claim 5
Dependent Claim
33 words
A method as in claim 1 or 2, wherein the trigger signal is derived from the curve representing the time behaviour of the working electrode current after the adjustment of a new potential.
Claim 6
Dependent Claim
70 words
A method as in claim 4 , wherein the trigger signal is produced when a zero passage (t₁) of the time derivative (D(t)) of the curve representing the time behaviour of the working electrode current has occurred, and the values of the function (D(t)) around the zero passage (t₁) have remained within a predetermined interval (-D t , +D t ) for at least a predetermined time T w .
Claim 7
Independent Claim
51 words
A method as in any of the preceding claims, wherein - the electrochemical detector (20) is coupled to the separation column (25) of a liquid chromatograph (21) , - the trigger signal triggers an injection of the sample into the separation column (25), and - the separated sample is electrochemically detected.
Claim 8
Dependent Claim
183 words
An electrochemical detector for detecting electroactive samples, comprising: - an electrochemical cell (11) for receiving liquid including the sample, - a working electrode (1), - means (30,32) for applying a potential (U in ) in the cell (11) between the liquid in the cell (11) and the working electrode (1), - means (31,33) for measuring the current created at the working electrode (1) by the sample, characterized by control and data processing means (34) coupled to the means (30,32) for applying a potential in the cell (11) and coupled to the means (31,33) for measuring the current created at the working electrode (1), said control and data processing means (34) being operative to - successively apply a plurality of potentials (Pot1,Pot2,Pot3) in the cell (11), the values of said plurality of potentials corresponding to a sequence of discrete values ranging from an initial to a final value, - produce a trigger signal after each adjustment of a new potential value indicative of a stabilization of the working electrode current, and - cause electrochemical detection of the sample in response to the trigger signal.
Claim 9
Dependent Claim
183 words
An electrochemical detector for detecting electroactive samples, comprising: - an electrochemical cell (11) for receiving liquid including the sample, - a working electrode (1), - means (30,32) for applying a potential (U in ) in the cell (11) between the liquid in the cell (11) and the working electrode (1), - means (31,33) for measuring the current created at the working electrode (1) by the sample, characterized by control and data processing means (34) coupled to the means (30,32) for applying a potential in the cell (11) and coupled to the means (31,33) for measuring the current created at the working electrode (1), said control and data processing means (34) being operative to - successively apply a plurality of potentials (Pot1,Pot2,Pot3) in the cell (11), the values of said plurality of potentials corresponding to a sequence of discrete values ranging from an initial to a final value, - produce a trigger signal after each adjustment of a new potential value indicative of a stabilization of the working electrode current, and - cause electrochemical detection of the sample in response to the trigger signal.
Claim 10
Dependent Claim
25 words
An electrochemical detector as in claim 7, wherein the trigger signal is produced a predetermined time interval after the adjustment of a new potential value.
Claim 11
Dependent Claim
32 words
An electrochemical detector as in claim 7, wherein the trigger signal is derived from the curve representing the time behaviour of the working electrode current after the adjustment of a new potential.
Claim 12
Dependent Claim
50 words
Use of an electrochemical detector as in any of the claims 7 to 9 for detecting sample components leaving the separation column (25) of a liquid chromatograph (21) , wherein the trigger signal is supplied to the liquid chromatograph to cause an injection of the sample into the column (25).
References Cited (Backward Citations)
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