US5185263A
Expired / Lapsed
US
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Method for calibration of a measurement apparatus
Assignee: AVL Medical Instruments AG
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Filing: 1991-11-04
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Granted: 1993-02-09
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Expires: 2011-11-04
Abstract
Abstract In order to calibrate a measurement apparatus used for determining at least the pH and pCO2 values in aqueous media, two aqueous base solutions A and B with good storage stability are mixed at a defined ratio immediately prior to calibration, the desired pH and pCO2 values being provided for calibration of the measuring electrodes of the measurement apparatus only after chemical reaction of the base solutions A and B has taken place.
Inventors
- 👤 Herbert Kroneis
- 👤 Hermann Marsoner
- 👤 Taghi Noormofidi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:23
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/26; G01N27/416; G01N27/4163; G01N27/4165; Y; Y10; Y10T; Y10T436/00; Y10T436/10; Y10T436/107497; Y10T436/11; Y10T436/115831
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
181 words
A method of calibrating a measurement apparatus that contains measuring electrodes and can be used to determine the pH and pCO 2 values of aqueous sample media, said method comprising the steps of providing two aqueous base solutions A and B which will react with one another when mixed but which will remain stable with respect to CO 2 content when exposed to ambient air, storing said two aqueous base solutions A and B in separate storage containers, mixing said base solutions A and B at a predetermined ratio such that they will react and form a calibration liquid having predetermined pH and pCO 2 values, immediately passing said calibration liquid to said measurement apparatus so as to contact said measuring electrodes, and taking calibration readings from said measuring electrodes, wherein said base solution A contains an acid component of a pH buffer system and said base solution B contains carbonate and bicarbonate, wherein a pCO 2 value resulting from the bicarbonate/carbonate ratio is obtained in said base solution B, which corresponds to a mean pCO 2 value of ambient air.
Claim 2
Independent Claim
181 words
A method of calibrating a measurement apparatus that contains measuring electrodes and can be used to determine the pH and pCO 2 values of aqueous sample media, said method comprising the steps of providing two aqueous base solutions A and B which will react with one another when mixed but which will remain stable with respect to CO 2 content when exposed to ambient air, storing said two aqueous base solutions A and B in separate storage containers, mixing said base solutions A and B at a predetermined ratio such that they will react and form a calibration liquid having predetermined pH and pCO 2 values, immediately passing said calibration liquid to said measurement apparatus so as to contact said measuring electrodes, and taking calibration readings from said measuring electrodes, wherein said base solution A contains an acid component of a pH buffer system and said base solution B contains carbonate and bicarbonate, wherein a pCO 2 value resulting from the bicarbonate/carbonate ratio is obtained in said base solution B, which corresponds to a mean pCO 2 value of ambient air.
Claim 3
Dependent Claim
21 words
A method according to claim 1, wherein said base solution B additionally contains an alkaline component of said pH buffer system.
Claim 4
Dependent Claim
34 words
A method according to claim 1, wherein a pCO 2 value resulting from the bicarbonate/carbonate ratio is obtained in said base solution B, which corresponds to a mean pCO 2 value of ambient air.
Claim 5
Dependent Claim
35 words
A method according to claim 1, wherein inactive salts are added to at least one of said base solutions A and B, in order to adapt ionic strength to that of said aqueous sample media.
Claim 6
Dependent Claim
35 words
A method according to claim 3, wherein inactive salts are added to at least one of said base solutions A and B, in order to adapt ionic strength to that of said aqueous sample media.
Claim 7
Dependent Claim
26 words
A method according to claim 4, wherein at least one salt of a group consisting of NaCl and KCl is used as said pH inactive salt.
Claim 8
Dependent Claim
24 words
A method according to claim 1, wherein said pH buffer system is selected from a group of phosphate buffers and water-soluble organic amino buffers.
Claim 9
Dependent Claim
33 words
A method according to claim 1, wherein at least a two-point calibration is carried out, for which calibration at least two different mixing ratios of said base solutions A and B are selected.
Claim 10
Dependent Claim
14 words
A method according to claim 8, wherein said two selected mixing ratios are reciprocals.
Claim 11
Dependent Claim
16 words
A method according to claim 9, wherein said two selected mixing ratios are 1:2 and 2:1.
Claim 12
Dependent Claim
40 words
A method according to claim 1, wherein a dye is added to one of said base solutions A and B and wherein said mixing ratio of said base solutions is tested by means of optical methods, such as absorption measurements.
Claim 13
Dependent Claim
43 words
A method according to claim 1, wherein one of said base solutions A and B is equilibrated with oxygen from ambient air immediately before calibration, and wherein a pO 2 calibration is carried out in addition to said pH and pCO 2 calibrations.
Claim 14
Dependent Claim
41 words
A method according to claim 12, wherein equilibration of one of said base solutions A and B with oxygen is performed in a piece of silicone tubing between a storage container of said respective base solution and said corresponding measuring electrodes.
Claim 15
Dependent Claim
31 words
A method according to claim 13, wherein for zero point calibration of pO 2 , oxygen is removed from one of said base solutions A and B by a cathodic reaction.
Claim 16
Dependent Claim
24 words
A method according to claim 13, wherein for zero point calibration of pO 2 a solution C is used which contains an oxygen-reducing agent.
Claim 17
Dependent Claim
43 words
A method according to claim 15, wherein said oxygen content of said solution C used for zero point calibration of pO 2 is checked by adding a redox indicator, wherein color of said redox indicator changes upon transition from oxidized to reduced state.
Claim 18
Dependent Claim
51 words
A method according to claim 15, wherein said oxygen-reducing agent is Na 2 SO 3 and wherein said oxygen content of said solution C is checked by adding a pH indicator which will undergo a change in color when the pH of said solution C is shifted from 9 to 7.
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