Method, apparatus and solution for calibration of partial pressure value
First Claim
1. A method for the measurement of the partial pressure of a gas in a liquid sample which comprises the steps:
- a) providing a calibration liquid having a defined concentration of a dissolved precursor of a gas, the liquid having a composition such that, upon exposure to light, the dissolved precursor reacts to form the gas;
b) exposing an aliquot of the calibration liquid in an exposing means to light of sufficient wavelength, intensity and duration to convert the precursor substantially completely to the gas;
c) conveying the exposed aliquot with the converted precursor to a measuring chamber for contact with a measuring element for the partial pressure of the gas;
d) making a measurement with the measuring element on the exposed aliquot with the converted precursor;
e) conveying the exposed aliquot with the converted precursor away from the measuring element and conveying a liquid sample having an analyte value of the partial pressure of the gas into the measuring chamber in contact with the measuring element;
f) making a measurement with the measuring element on the liquid sample; and
g) comparing the measurement made with the measuring element on the liquid sample to the measurement made with the measuring element on the exposed aliquot of calibration liquid.
5 Assignments
0 Petitions
Accused Products
Abstract
Electrodes for the measurement of pCO2 and/or pO2 are calibrated with an exposed aliquot of a calibration liquid. A constituent such as a ferrioxalate salt in the calibration liquid is converted to the gas in a reproducible concentration by exposure of the aliquot to light. In some instances, the calibration liquid is equilibrated with air prior to exposure. Some mechanisms of light generation of carbon dioxide also consume oxygen, so as to depress the pO2 value by a reproducible amount. The use of two different calibration liquids enables both one-point and two-point calibration of the Clark oxygen electrode and the Severinghaus pCO2 electrode of a blood gas instrument.
46 Citations
21 Claims
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1. A method for the measurement of the partial pressure of a gas in a liquid sample which comprises the steps:
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a) providing a calibration liquid having a defined concentration of a dissolved precursor of a gas, the liquid having a composition such that, upon exposure to light, the dissolved precursor reacts to form the gas; b) exposing an aliquot of the calibration liquid in an exposing means to light of sufficient wavelength, intensity and duration to convert the precursor substantially completely to the gas; c) conveying the exposed aliquot with the converted precursor to a measuring chamber for contact with a measuring element for the partial pressure of the gas; d) making a measurement with the measuring element on the exposed aliquot with the converted precursor; e) conveying the exposed aliquot with the converted precursor away from the measuring element and conveying a liquid sample having an analyte value of the partial pressure of the gas into the measuring chamber in contact with the measuring element; f) making a measurement with the measuring element on the liquid sample; and g) comparing the measurement made with the measuring element on the liquid sample to the measurement made with the measuring element on the exposed aliquot of calibration liquid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An apparatus for measuring the partial pressure of a gas in a liquid sample which comprises:
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a) exposure means for exposing an aliquot of a calibration liquid to light; b) a measuring chamber; c) first conveying means for conveying an exposed aliquot of calibration liquid from the exposure means to the measuring chamber; d) a measuring means in operative contact with the measuring chamber; e) second conveying means for conveying a liquid sample into the measuring chamber; and f) comparator means for comparing the measurement made by the measuring element on the liquid sample with the measurement made by the measuring element on the exposed aliquot of calibration liquid. - View Dependent Claims (14, 15, 16)
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17. A method for the measurement of the partial pressure of oxygen and carbon dioxide in a liquid sample which comprises the steps:
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a) providing first and second calibration liquids comprising aqueous ferrioxalate solutions; 1) the first calibration liquid having a pH of 0 to 2, an oxalate concentration of 0.6 to 1.5 millimoles per liter, a molar ratio of iron(III) to oxalate of 5;
1 to 100;
1 and an iron concentration of 3 to 150 millimoles per liter; and2) the second calibration liquid having a pH of 0 to 2, an iron concentration of 0.1 to 0.5 millimoles per liter, a molar ratio of iron (III) to oxalate of 1;
1 to 1;
7200 and an oxalate concentration of at least 0.3 millimoles per liter;b1) exposing an aliquot of the first calibration liquid to light of sufficient wavelength, intensity and duration to convert the oxalate substantially completely to carbon dioxide without affecting the oxygen partial pressure; c1) conveying the exposed aliquot of first calibration liquid to a measuring chamber for contact with measuring elements for partial pressure of oxygen and of carbon dioxide; d1) making a measurement with the measuring elements on the exposed aliquot of first calibration liquid; b2) exposing an aliquot of the second calibration liquid to light of sufficient wavelength, intensity and duration to convert the ferrioxalate substantially completely to carbon dioxide with a concombitant reduction of oxygen partial pressure; c2) conveying the exposed aliquot of second calibration liquid to the measuring chamber for contact with the measuring elements for the partial pressures of oxygen and carbon dioxide; d2) making measurements with the measuring elements on the exposed aliquot of second calibration liquid; e) conveying a liquid sample having analyte values for the partial pressures of oxygen and carbon dioxide into the measuring chamber in contact with the measuring elements for the partial pressures of oxygen and carbon dioxide; f) making measurements with the measuring elements on the liquid sample; and g1) comparing the measurements made of oxygen partial pressure with the measuring element therefore on the liquid sample with the measurements made by that measuring element on the aliquots of first and second calibration liquids, and g2) comparing the measurements made of carbon dioxide partial pressure with the measuring element therefore on the liquid sample with the measurements made by that measuring element on the aliquots of first and second calibration liquids. - View Dependent Claims (18, 19, 20, 21)
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Specification