DE2727140A1 - SYNTHETIC REFERENCE LIQUID FOR QUALITY CONTROL AND / OR CALIBRATION OF BLOOD GAS MEASURING DEVICES - Google Patents

Description

PATENTANWÄLTE-: A. ÜRÜNECKER

WPL - .. «3.

H. KINKELDEY ft "or-« «

W. STOCKMA.R

K. SCHUMANN P. H. JAKOB

COT-ING.

G. BEZOLD

EAJ) IOMETEH A / S <* «« «« .ο «

EmdrupveJ 72, _{8 MUNICH 22}

BK-24O0 Copenhagen maximiuian.tr * · »« « _a

.16. June 1977 P 11 769-64 / ku

Synthetic reference fluid for quality control and / or the calibration of blood gas measuring devices

The invention relates to a reference liquid for quality control and / or calibration of blood gas measuring devices and a method for their manufacture.

Blood gas measuring apparatus are known which are used to measure the pH of the blood, the concentration of dissolved carbon dioxide in the blood, expressed as P (C (^) (partial pressure of carbon dioxide) and the concentration of dissolved oxygen in the blood, expressed as P. (Oo) partial pressure of oxygen) are constructed by means of suitable measuring electrodes; and a known fully automatic blood gas measuring apparatus (Radiometer ABL1, described for example in US-PS 3 874- 850) also measures the same time nor the blood hemoglobin content (Hb), which is otherwise usually measured separately.

Various parameters can be derived from these four central parameters Parameters are calculated which are of great importance for the assessment of the so-called acid-base state

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of the organism 'are.

The above measurements are all relative measurements, with the unknown sample being compared with standard samples. Hence the quality of this standard? decisive for the quality of the measurement of the individual parameter.

When using manual or semi-automatic blood measuring devices nowadays, a great technical understanding on the part of the operator of the measuring device is necessary in order to obtain measurements of satisfactory quality. The technical training level of the operating personnel can be lower if a fully automatic self-calibrating apparatus is used, for example of the type described in the aforesaid U.S. Patent 3,874-850 is; however, this does not remove the need or desire to measure the quality of the apparatus including the quality of the standards, calibration liquids, etc. by means of a known reference value.

Although it is generally known in principle to check a measuring apparatus by entering a sample of known properties, this represents a major problem for apparatus for measuring pH, P (CO ₂ ), P (O ₂ ) and possibly Hb.

A sample of this type (blood sample or other aqueous solution) is generally not stable over long periods of time (CO ₂ and O ₂ escape from the sample), which means that the sample must be prepared on the spot by the user. Usually this poses problems such as excessive labor, expensive extra equipment and uncertainty because the manufacturing process is technically rather complicated.

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Everywhere today there is an interest in a control system for measuring the values of apparatus of the type mentioned, since these apparatus are directly connected to the treatment of Patient and often in extremely critical circumstances, e.g. during surgery.

In the United States of America, Congress has been grappling with this problem over the past few years and At the moment, the legislature tends to require the "blood data supplier", i.e. the head of the laboratory, to provide him at any time can prove that the measuring equipment used can produce reliable data. For this he should provide evidence that that the measuring apparatus was tested by means of a system independent of the normal system of the apparatus (quality control).

Today there is a general need outside of the USA as well if possible, small containers with samples of known composition and large containers for this quality control To be able to buy reliability.

All commercially available blood gas measuring devices have to be calibrated frequently, usually every few hours. For For this purpose, according to the prior art, various calibration liquids are used for certain types of apparatus, from some of which, e.g. pH buffer mixtures, are commercially available in small containers and have high reliability with regard to the Maintain the nominal pH while the Calibration liquids for calibrating other parts of the measuring apparatus, e.g. the P ^ CC ^ measuring device and the P (Op) measuring device, not currently commercially available in easy-to-handle packs are. Some technically advanced blood gas analyzers, e.g. the fully automatic Badiome-

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ter ABL1 blood gas measuring device, use solutions which are calibrated in the device itself with known gas mixtures, in order to obtain well-defined values for pH, F (COp) and F (Op), and the calibration solutions thus produced in the apparatus, which have well-defined values are used for calibration within of the device without being transferred to separate containers.

leads to become.

It would be of great advantage to have the real calibration of the blood gas measuring apparatus, especially a semi-automatic apparatus, by means of to be able to carry out a handy comparison liquid which, while maintaining its relevant values, can be produced with high accuracy and reliability, packed in suitable fortion packs, distributed and stored, so that calibration of the blood gas measuring device simply by introducing a unit amount or a portion thereof into the device can be performed without the need for any special preparation or inspection of the fluid.

The present invention provides a reference fluid that can be used for quality control and / or calibration of blood gas measuring devices. The reference liquid is known with regard to the parameters: pH, F (CO ₂ ), F (Op) and, if desired, with regard to a parameter which represents the hemoglobin concentration.

US-FS 3,681,255 and Danish patent application 1261/72 mention the possibility of using a single calibration liquid with known hydrogen carbonate ion concentration, known partial pressure of carbon dioxide (and accordingly in accordance with the known Henderson-Hasselbalch equation known pH) and known partial pressure for oxygen to calibrate the measuring electrodes in blood gas measuring devices and according to

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of said US-PS, the calibration liquid can be delivered to the consumer in a gas-tight container.

It is true that calibration liquids of this type are, because of their inclusion in a gas-tight container, while maintaining the known parameters in principle for quality control and calibration of blood gas measuring devices suitable; in practice using known calibration fluids, in other words with the actual one Carrying out quality control or calibration by introducing the reference liquid into the blood gas measuring apparatus however, it is difficult to meet such precise requirements as can be reasonably expected of a comparative liquid can be provided for calibration and quality control. P (Oo) control in particular brings serious difficulties with itself, and with the calibration liquids according to the state of the art, which are contained in gas-tight sealed containers it is not possible to achieve a reliable control or calibration of the P (02) system under all circumstances.

The reference liquid according to the invention is contained in a gas-tight container and shows at a certain temperature a known pH, a known partial pressure of COg, and a known partial pressure of oxygen and additionally contains oxygen, which is reversible in a dispersed organic Substance is included, which can absorb a larger amount of oxygen than water per unit volume, as well as optionally a coloring ingredient.

If the reference liquid according to the invention contains a coloring component, it can be used for quality control and / or to calibrate the apparatus with regard to the determination of the amount of hemoglobin in addition to quality control and / or calibration of the Apparatus for the determination of pH, P (COo) and P (Op)

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be turned.

In the reference liquid according to the invention, the problem of the unsatisfactory reliability of the control or calibration of the P (O ₂ ) system is solved in that the liquid (which is generally an aqueous liquid) contains oxygen which is reversibly contained in a dispersed organic substance which can absorb a larger amount of oxygen per unit volume than water in order to increase the (^ -capacity. This leads to an increased "oxygen buffer capacity", so that any loss or gain of oxygen that may occur during handling and measurement, leads to a relatively small change in the P (O ₂ ) value of the solution, this being the parameter against which the P (Og) part of the apparatus is to be checked and / or calibrated.

The term "dispersed organic substance" is intended to mean both organic substance which is so finely dispersed that a true or colloidal solution of the organic substance in the (usually predominant aqueous) liquid is obtained, as well as an organic substance in emulsion or suspension in the predominant aqueous liquid mean. This meaning can also by the term "dispersed ¹¹ are expressed, which in the present context the three terms" dissolved, "emulsified" and "suspended" covers.

The expression "reversibly contained" is intended to indicate that the Oxygen is present in the organic matter in such a way that the organic matter is subject to handling and Hot conditions can supply or absorb oxygen, so that the organic substance due to its ability to produce larger To contain amounts of oxygen per unit volume as water, increase the oxygen buffer capacity of the reference liquid

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can. The expression "reversibly contained ^11" can include both those cases in which the oxygen is dissolved in the organic substance or is physically bound in some other way, as well as those cases in which the oxygen is predominantly chemically attached to or in the organic substance in question is bound, in particular is bound in a complex. '.

As dissolved organic substances in which the oxygen is dissolved or otherwise mainly physically bound, water-soluble organic compounds can be used that do not adversely affect the other parameters in the reference liquid influence and which have a much greater dissolving power for oxygen than water. It is known that the Solubility of oxygen in various water-soluble organic compounds, e.g. alcohols such as Xthanol, Propanol and tert-butanol, is considerably larger than that Solubility of oxygen in water; and in an aqueous solution of such organic compounds, in other words, e.g. an aqueous solution of one of the alcohols mentioned, is the solubility of oxygen and, accordingly, the Oxygen buffer capacity considerably larger than in one aqueous solution without such dissolved organic components. However, since increasing the oxygen solubility necessary to achieve a reliable comparison liquid for the calibration or control of the PCC ^ system is desired, is very large and corresponds to at least about 5 times, preferably about 10 to 23 times, solubility in water and there such large increases in solubility Difficult to obtain with dissolved organic substances, their use alone is not preferred Embodiment according to the present invention.

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If the reference liquid according to the invention contains, as the organic substance which increases the oxygen buffer capacity, a dissolved organic substance in which oxygen is considerably more soluble than in water, the concentration of this dissolved substance is normally 10 to 60%, in particular 20 to 40 %. of the total volume.

The solubility of oxygen in various organic Materials that cannot be regarded as essentially water-soluble is even greater than the oxygen solubility in the above water-soluble organics, Such water-insoluble organics that a big one Have solvent power for oxygen, are e.g. oils or oily synthetic organic substances and organic polymers. Examples are hydrocarbons such as isooctane, Silicone oils and silicone rubbers as well as fluorocarbon compounds, i.e. fluorinated, especially perfluorinated hydrocarbons and compounds containing such fluorinated hydrocarbons

as well as their polymers. With such Water-insoluble organic compounds that are liquids of lipoid character or solid substances can be dispersions which are lipoid-in-water type emulsions or suspensions. For the purposes of the present invention Such systems have the advantage that the great oxygen-dissolving power of the lipoids or solids large oxygen buffer capacity while the liquid still retains its property as an aqueous solution and hence the establishment of a P (COg) ZpH buffer system within allow. Therefore, particularly preferred comparison liquids according to the invention contain oxygen, the emulsified in or suspended non-water-soluble organic substances is dissolved. Of course, it is also possible to combine

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to use water-soluble and water-insoluble organic substances with a large oxygen absorption capacity.

In general, the following criteria are used in selecting water-insoluble organic substances for use to be considered as an oxygen carrier:

1. The oxygen carrier must have high dissolving power for oxygen (reversible);

2. the oxygen carrier should have little or no protolytic Have activity;

3. the organic phase, which consists of the oxygen carrier, should be dispersible in an aqueous buffer to meet the following conditions:

a) high concentration of organic phase (which gives a high Og capacity of the Geoisch);

b) the mixture should be stable;

c) the density of the mixture should be used for blood gas measuring devices which contain salt bridges and the use of which depends on it, that the blood is less visible than saline, less than or equal to the blood density;

d) the viscosity of the mixture should not be too high;

4. The oxygen carrier should be largely chemically inert (so as not to destroy the construction material in the blood gas measuring apparatus);

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5. The oxygen carrier should preferably be harmless be able to handle and

6. the oxygen carrier should preferably be a commercially available material and therefore be cheap and readily available .

Ils explanation of the increase in the solubility for oxygen, which is obtained by using one of the mentioned, water-soluble or water-insoluble substances, it should be mentioned that the solubility of O ₂ (at an oxygen pressure of 1 atm and 25 ° C) in water 2.4 % v / v, while in ethanol it is 21 % v / v, in olive oil 12% v / v, in fluorocarbon compounds typically 50 % v / v, in silicone rubbers typically 18 % v / v, in silicone oils typically 20 % v / v and in isooctane is about 36 % v / v.

The amount of dissolved oxygen in various systems as a function of the partial pressure of oxygen (simple logarithmic representation) is shown in FIG. 1, in which '"fluorocarbon compound" means perfluorotributylamine. It should be emphasized that even a small change in the amount of oxygen results in a very large P (0 ₂₎ -Difference in pure water, while volume a change in oxygen, for example in the fluorocarbon compound has a much lower P (O ₂₎ causes -Change, and that, for example, a 40% emulsion of the fluorocarbon compound in water has a much better oxygen buffering capacity _{than water, that is, shows much less P (O 2} ) change for a given change in oxygen content.

If the reference liquid according to the invention is an emulsion or suspension, the emulsified or suspended phase preferably represents at most 60 % of the total volume, in particular

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40 to 70%, since the water phase is of course a sufficient one Should have a proportion in order to avoid a deterioration in the quality of the pH measurement. Hence it is clear that we are putting together emulsified or suspended constituents of the liquid according to the invention are preferably selected, which have a particularly high solubility for oxygen, e.g. the above-mentioned fluorocarbon compounds.

As examples of fluorocarbons and those containing fluorocarbons Compounds, in other words, for fluorocarbon Compounds which are useful for the purposes of the present invention can be perfluorotributylamine ((C ^ Fq) ^ N) sold by the 3M Company under the name "FC 43" will be mentioned, perfluoromethylcyclohexane and perfluorodimethyldecalin.

Because of their good emulsifying properties and high ability Dissolving oxygen, perfluorotributylamine is the preferred compound. As an example of a silicone oil that is available as emulsified phase is useful in the reference liquid according to the invention, be the silicone oil that is available from Dow Corning under the name "200 Silicone Oil" is sold, and as an example of a silicone rubber, which as a suspended phase which can be used in the reference liquid according to the invention is the silicone rubber CAF4 / 60 Bhodorsil from Bhone Poulenc, Paris, called.

According to a particular aspect of the present invention, a suspended solid is used which is porous and may contain oxygen or an oxygen-containing gas in its cavities; a material suitable for this purpose is porous silicone rubber or rubber. One for that purpose

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useful porous silicone rubber can be made e.g. by prior to or during the vulcanization of the silicone rubber creates an overpressure, which is then released during vulcanization. More useful for this purpose Porous silicone rubber can also be made by adding a non-volatile solvent to the rubber prior to vulcanization for silicone rubber, e.g. methanol, is dispersed and then the silicone rubber is vulcanized and the volatile Substance evaporates.

To obtain a stable emulsion or suspension, you can it may be necessary that the reference liquid according to the invention contains a suitable emulsifying or suspending agent; and this agent can be of any type which the Parameters that are to be determined by means of the reference liquid are not adversely affected and a stable emulsion or suspension of the selected organic material results. Amalgamating or suspending agents suitable for this purpose are commercially available. As an example of an 'emulsifier, which is suitable for the production of fluorocarbon emulsions in water for the purposes of the invention has been shown to be Pluriol PE 6800 from BASP (polyoxypropylene-polyoxyethylene) called.

As mentioned above, the organic substance in which the oxygen is in the reference liquid according to the invention can be reversible is contained to be a substance to which oxygen chemically reversible, in particular complex, is bound.

Most chemical processes involving oxygen are "characterized by being essentially irreversible." are, so that the oxygen-containing compound formed once no longer has a significant amount of oxygen.

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Freiseiz en to measure; in other words, the irreversible ones Process formed oxygen-containing compounds are not suitable, the oxygen buffer capacity of the invention Increase reference fluids.

There are reversible oxygen processes, for example in the blood hemoglobin molecule, which can reversibly take up and release considerable amounts of oxygen and which would therefore in principle be excellently suited for the purposes of the present invention. However, like other biological substances, such as proteins or protein-containing complexes, ^{the hemoglobin molecule is relatively unstable outside the organism 1} and therefore comparative liquids have been made with hemoglobin or other biological substances, such as proteins or protein-containing complexes, as an organic substance that increases the oxygen capacity , the disadvantage that they are only stable for a relatively short time if special precautionary measures are not taken to ensure their stability, e.g. by freezing the reference liquid immediately or shortly after its manufacture and packaging, distribution and storage of the reference liquid in frozen form, addition of suitable stabilizers to prevent chemical degradation and suitable sterilization or addition of antibiotics to prevent degradation by microorganisms.

However, other, simpler and less sensitive organic compounds than the hemoglobin molecule are known to be can bind reversibly oxygen complex. Examples of such non-biological compounds are especially organometallic compounds of transition

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metals, especially cobalt or iron, in which the metal is bound, usually through a complex bond, to nitrogen-containing groups, e.g., transition metal complexes Bit porfyrin-like compounds, such as iron (II) phthalocyanine tetrasulfonic acid.

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For the purposes of the present invention, the organic substance which can chemically, in particular complex, reversibly bind oxygen should preferably be one which has a suitable position of equilibrium for the reversible oxygen reaction in question, ie an equilibrium position which resembles that of hecoglobin (the closest resemblance to authentic blood) and / or an equilibrium position that gives a maximum amount of oxygen buffer capacity at or around the P (0 ₂ ) value to be consumed by the reference fluid.

With regard to the equilibrium of the oxygen reaction of hemoglobin, the following applies when the oxygen uptake of the blood is viewed in a simplified way:

Hb + ^η ^ 3bO ₂ ,

where Hb is the enoglobin molecule, Op is the oxygen molecule and mean the oxygen-containing hemoglobin faecal complex.

The solubility of oxygen (in free form) in the aqueous phase of the blood can reasonably be set at 1.4 10 "" moles of oxygen per Z per torr of oxygen partial pressure. Empirically, at an oxygen partial pressure of 27 torr, there are equal amounts of hemoglobin in the Hb fora and, on the other hand, of hemoglobin in the HbOp form in the blood. the concentration of dissolved oxygen in the water phase of the blood is as follows:

/ O ₂ 7 - 1.4 10 "" ⁶ 27 / v / 3.8 10 ⁵

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The stability constant K for the oxygen-containing hemoglobinkompiex is:

K =

3.8 χ

It follows that, among the organic compounds forming an oxygen complex, which bind oxygen in the same way as hemoglobin, that is, according to the above reaction scheme, as for use as an oxygen buffer in a comparative liquid which has the properties of blood From this point of view, ideal compounds are compounds for which the stability constant of their oxygen complex is etx * a 10 ', for example in the range from 10 ^ to 1CK'%, in particular 10 ⁴ to 10 ⁵ .

ELn other type of organic compounds, different from hemoglobin, but reversibly forming complexes with oxygen, oxygen binds according to the reaction scheme:

2 L + O ₂ JL-O ₂ -L

where L is the ligand that can bind oxygen, and L-Oo is the complex compound in its oxygen-containing form.

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The stability constant of the above-mentioned complete compound in its oxygen-containing form LO ₂ -L is:

where {hj is the concentration of oxygen (in free form) dissolved in the system concerned. Like the stability constant calculated above for the oxygenated hemoglobin complex, this constant is also temperature-dependent to a certain extent; however, this temperature dependency can usually be neglected for the purposes of the present invention. If the concentration of L is denoted by <f \ and the concentration of L-Op-L by ß, (k + 2ß = c (compare the reaction scheme) or Λ »c where c is the total concentration of the ligand

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β β

O ² IO ₂ J (C - 2nd

β = K (C - 2P) ² IO ₂ ] (C - 2β) ² = C ² + 4β ² - 4c0

β = K [O ₂ Jc ² + 4Κ [Ο ₂ ] β ² - 4K [O ₂ ] c3 4K [O ₂ Jβ ² - 4KlO ₂ lcβ - β + K [O ₂ Ic ² = 0 4Κ [Ο ₂ ] β ² - (4K [O ₂ ] C + 1) β + K [O ₂ ] C ² = 0 (4K [O ₂ ] C + 1) ^(±) ~~ \ j (4KlO ₂ Jc + I) ² - 16K [O ₂ ] KlO ₂ ] c ^:

8KlO ₂ J

where β, as can be seen from the above , represents the concentration of complex-bound oxygen.

The total oxygen concentration in complex TOg systems is:

TO ₂ « & ^ 7 + ß,

where ßi ^ Jaxe is the concentration of dissolved oxygen and ß is the concentration of complex-bound oxygen.

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It is crucial for the suitability of the compound forming an oxygen complex for use in the liquid according to the invention that a suitable oxygen buffer capacity should be obtained around the oxygen partial pressure that the comparison liquid should have, which means that any loss of small amounts of oxygen from the liquid or any increase in small amounts of oxygen in the liquid, for example during handling of the liquid and during a calibration process, is intended to bring about the _{smallest possible change in P (O 2) in the liquid.} Of course, in principle, a high oxygen buffer capacity is achieved if the concentration of the sow in the reference liquid is high only off the complex-forming compound; however, the oxygen partial pressure around which the buffer effect has its maximum depends on the concentration mentioned as well as on the size of the stability constant K mentioned above. When composing a reference liquid according to the invention using a compound which forms an oxygen complex, the compound which forms an oxygen complex should therefore preferably select a compound in such a concentration that a maximum of oxygen buffer capacity around the oxygen partial pressure is achieved, which the reference liquid should have.

In practice, the oxygen buffer capacity for the above complex system can be defined as follows:

d ß

d log ZP ₂ 7

where ß and Z0 ^ 7 have the meanings given above, and therefore the maximum oxygen buffer capacity is the one at which

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d (log [O ₂ I) ²

= 0,

What

i_T of this function is equivalent to

d ² log

O.

the end

- = ^{K it} follows that ^t0 2 ^{1 =}

(c -

log [O ₂ ] = -log K + log 0 - 2 log (c

d (c - 20) d log

d log [O ₂ ] d (c -

d P d P

d log [O ₂ ] 1 ^λ

L = - (log e) - 2 1ος e (- 2)

d PP ^c - ^{2 [beta]}

d log 1O ₂ I.

1
_ = log e (£ +. _c _ 20

d P

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d ² log [O ₂ ] - log e

_L ₌ + log e (-4 (c - 20) (- 2))

d0 * '0 ²

d ² log [O ₂ ]

d 0 '

= log e

(c - 20)

It follows that

d ² log [O ₂ ]

= ο

d 0 '

for

(c - 20)

² = c ² +

80 ² = (c - 20) ² = c ^2. + 40 ² - 4c0

40 ² + 4 c0 - c ² = 0

-4c

0 =

± ~ \ / l6 c ² + 16 c ² _ - ] c (-) 4

0 =

= 0.207 * c

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On this basis, suitable stability constants for oxygen complexes for use in reference liquids can be calculated as an example, the oxygen partial pressure of which is one of the three values to which calibration should be carried out frequently, i.e. 500 mn Hg, 150 mm Hg and 50 mm Hg. The following apply here Relationships:

D 2) 3)

= 6 χ 10 ~ ⁴ mol / 1 (/ V ^ 500 Torr) = 2 χ 1 (T * mol / l (^
= 6 χ 10 ~ ⁵ mol / l (

Torr) 50 Torr)

If it is desired to use the liquid in a concentration of 10 mol / l in these cases, the following values are calculated for the stability constant K, those for the three mentioned / Öp7-V. ^r erte maximum oxygen buffer capacity the following result:

te O. 20] ²
207 ' [O ₂ ]
C. (compare c
0. »Ben;
207 * c (C. 0. 2 '0
603 .207 * c) ² [O ₂ ] (0. 586 'c) ² [O ₂ ] C. • [O ₂ ]

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0.603 _L.

10 'χ 6 χ 10 *

0.603 ζ,

zr = 3X10

a:

10 'χ 2 χ

0.603

-Λ

10 'χ 6 χ 10

Pig. 2 shows, as a simple logarithmic representation, the concentration of the total oxygen content as a function of the oxygen partial pressure for oxygen complexes with the three above-mentioned stability constants, each in a concentration of. 10. Mol / l in the reference liquid. It can be seen that the oxygen complex compounds (considerably greater steepness of the curve than for HPO) have a considerable oxygen buffer capacity in a wide area around the aforementioned partial pressures, so that a reduction or an addition of a certain amount of oxygen _t range mentioned only one percentage (relatively small) change in the oxygen partial pressure of the system.

Against the background of the examples given above and the Pig. 2 it can be stated that also for complex compounds, the oxygen according to the Eeakt ions schema

2L + 0 ~> LO ₀ -L bind, favorable stability con-

stood in the range from 10 ^p to 10 ", in particular 10 to ^.

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If the fiction, modern reference liquid as Sauerstoffpuff erkapazität-enhancing organic compound contains a compound forming an oxygen complex, the concentration of this compound is preferably between 10 "and 1 mol / l, in particular between 10 ^-5 and 5 x 10 *" ¹ Minor.

If the fiction, contemporary comparison liquid contains a coloring component that is supposed to represent hemoglobin and allows the use of the comparison liquid for quality control and / or calibration of the hemoglobin nessenden part of the bleeding apparatus, the coloring component is preferably one that has an absorption maximum at or near the isobestic point of the system hemoglobin / hemoglobin-oxygen -! - complex (Hb / EbOp), ie near the point at which the molar absorbance caused by Hb is the same as the molar absorbance caused by HbQ-, because "a Apparatus for measuring blood gas, which contains an hemoglobin-measuring part, is usually equipped with filters such that the absorption of the sample introduced is measured at or in a narrow area around the isobestic points, for example the points at 505 nm Dye with an absorption maximum around 500 na for use in the comparison according to the invention liquid suitable. Examples of such dyes are Amaranth, Allura Red and Ponceau 4-R, 70 % . The latter dye is a chemical azo dye with CI No. 16 255 (1956). The compound is the trisodium salt of 1- (4 - SuIfO-I-naphthylazo) -2-naphthol-6,8-disulfonic acid. The dye used should be present in the liquid in such a concentration that it corresponds to the extinction of human blood, which for Ponceau 4-R, 70 % is a concentration of about 1.7 g / l »\

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Pig. 3 shows the absorption curve of Ponceau 4 E.

If the reference liquid according to the invention is in the form of a If dispersion is present, the coloring component can also be dissolved in the disperse phase, which is the reference liquid gives the appearance of blood. Suitable dyes for this purpose are, for example, Grasol Fast Red BH from Ciba-Geigy and Sudan Bot 7B from BASF; these two dyes are soluble in silicone oil.

A particular aspect relates to a liquid for use as a comparison liquid or as a starting material for the production of a comparison liquid, the oxygen buffer system of which is completely or partially made of polymer-coated Microcapsules consists of at least one organic substance with a much greater ability to reversibly absorb oxygen than possess water. In its broadest meaning as a comparison fluid for quality control and / or calibration of measuring apparatus for P (Oo) (or as a starting material for the Production of such a comparison liquid) is the one mentioned Liquid characterized in that it has an aqueous phase and polymer-coated suspended in the aqueous phase Contains microcapsules, which contain at least one organic substance, the much greater ability to be reversible Oxygen absorption contained as water. In accordance with the explanations given below, this has Comparative liquid the ability to with a fixed Temperature a known pH, a known carbon dioxide partial pressure and a known partial pressure of oxygen if their water phase contains at least one pH buffer system; preferably contains its water phase, as explained below, both a hydrogen carbonate ion-carbon dioxide-pH buffer system as well as an additional pH buffer system, whereby the

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additional pH buffer system, preferably a phosphate buffer system is. The organic matter that is contained in the microcapsules can be any of the above that contain oxygen pufferkapazi did increasing substances, in other words, an organic substance that is a considerably larger one Ability to reversibly absorb oxygen as water.

In accordance with a preferred embodiment of the present invention, the polymer-coated oxygen carriers, which are in the form of microcapsules, according to those above in connection with suspended or emulsified Oxygen carriers mentioned criteria selected.

Preferred organic substances that can be contained in the microcapsules are hydrocarbons, fluorocarbon compounds, Esters (e.g. dibutyl phthalate) and silicone oils can be mentioned; particularly preferably contain Microcapsules isooctane or perfluorotributylamine and very particularly preferably a mixture of isooctane and perfluorotributylamine. When the microcapsules contain a mixture of isooctane and perfluorotributylamine, it is according to the invention particularly preferred that the volume ratio between isooctane and perfluorotributylamine 5 to 9: 4 · to 10, in particular 7 to 8: 3 to 2; A volume ratio of about 3 ί 1 is very particularly preferred, since this is the optimal one Density of the mixture results.

The polymer coating of the microcapsules can be any polymer that is present in situ at the interface between a organic phase and an aqueous phase either by interfacial polymerization or can be formed by interfacial precipitation. As examples of substances that are caused by interfacial

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Polymerization can be formed, be proteins, polyamides (nylon), polyurethane, polyurea, or polysulfonamide Called polyvinyl ester; Examples of polymers that can be precipitated at the interface are cellulose nitrate, Protein, polystyrene and "Silastic" (the latter compound having to be vulcanized afterwards) according to the invention the polymer coating of the microcapsules is preferably a non-biological and non-proteinaceous material, particularly nylon formed in situ.

The size of the microcapsules is preferably in the range from 1 to 5 µm and the polymer layer is preferably µm Range from 30 to 60 mu thick.

By including the oxygen buffer capacity-increasing substance in a polymeric coating in the form of microcapsules, firstly, a more stable suspension than by Emulsifying the same substances obtained and, secondly, the advantage that oxygen buffer capacity-increasing Substances which otherwise have difficulties because of their aggressiveness to parts of the blood gas measuring apparatus, e.g. the polypropylene membranes of the oxygen electrodes, in the reference liquid essentially without any Difficulties can be used. Furthermore, by using the microcapsules, it is possible to produce various To combine substances in the organic phase in such a way that their density is equal to or very similar to the density of water is what counteracts any tendency of the disperse phase to separate from the aqueous phase, and the combination of various substances can also improve other properties, e.g. the strength and smoothness of the Polymer membrane around the microcapsules contribute. Therefore, for example, the addition of carbon tetrachloride contributes to encapsulating in nylon

709852/1004

tem isooctane contributes to the softness of the nylon membranes increase and decrease the tendency of the microcapsules to agglomerate.

The preparation of a microcapsule suspension of the type described above is carried out by using at least one organic Substance which has a considerably greater ability to reversibly absorb oxygen than water, in an aqueous phase suspended under such conditions that the individual suspended particles are coated with a polymeric material. A technique that in certain respects this procedure is described in the literature ("Semipermeable Aqueous Microcapsules", T.M.S. Chang, F.C. Macintosh, S.G. Mason, Can. J. of Physiology and Pharmacology, 44, 115-128 (1966), "Artificial Cells", Thomas Ming Swi Chang, Charles C. Thomas, Springfield, Illinois, USA 1972). In these papers, methods for making thin, stable polymer membranes are discussed aqueous microdroplets either by interfacial polymerization or by interfacial precipitation. The included aqueous phase could contain enzymes and / or other proteins and was made up of a continuous aqueous phase of the semipermeable membranes formed. With the above The two aqueous phases thus separated served as models for biological cell walls. Through such a The study of the individual cell functions was made easier. For this a semipermeable membrane was placed between two aqueous phases needed so that the exchange of water, salts and small molecules could take place while larger molecules (e.g. enzymes) were retained. The production of the polymer membranes around the aqueous microdroplets was carried out according to the prior art in the following way:

1. The aqueous protein solution (which may be organic

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Diamine) was treated with a suitable soap in an organic liquid emulsified;

2. A polymer membrane was formed around each droplet by adding a suitable material to the continuous phase. The membrane formation was carried out either by interfacial polymerization, in other words by a chemical process, or by interfacial precipitation, in other words by a physical process, depending on the lower solubility for a polymer in the interface;

3. The microcapsules formed were removed from the organic phase by means of suitable solvents and / or surface-active agents and suspended in an aqueous medium. In a particular example, the previously researched interfacial polymerization (Morgan and Kwolek, J. Pol. Sci. 40 , 299 * 1959) was used between a water-soluble aliphatic diamine and the solution of a dicarboxylic acid chloride in an organic solvent.

Chang et al. showed that polymerization also took place when the aqueous phase was finely divided in the organic phase Template.

In contrast to the prior art mentioned above, the present invention to a stabilization of a disperse organic phase in an aqueous medium and a reduction the diffusion rate of the liquid phases through the membrane, and a typical difference in comparison with the method according to Chang et al. is that in the process according to the invention an organic phase and not the aqueous phase is finely divided is.

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In preferred embodiments of the process of the invention, the polymeric coating material is formed by interfacial polymerization between polymer-forming constituents, one of them in the organic phase and the other is in the aqueous phase. For example, in accordance with a preferred embodiment, nylon is thereby described in formed at the interface that the organic phase contains a sebacoyl chloride and the aqueous phase contains hexanediamine.

The organic phase can be suspended in the aqueous phase in any suitable manner; According to the invention, however, it is preferred that the organic phase is suspended in the aqueous phase by spraying it into the aqueous phase by means of a nozzle. For example, microcapsules with encapsulated isooctane, which is suspended in an aqueous phase, can be produced by pouring isooctane with a 10 % sebacoyl chloride content through a nozzle into an aqueous solution containing hexanediamine and an emulsifier, e.g. FC-128 from 3M -Company, which is the potassium salt of fluorinated alkyl carboxylate, sprays. For example, 100 to 500 ml of isooctane with a content of 10% sebacoyl chloride can be introduced by spraying into 5 liters of aqueous solution containing 0.1 kg of 1,6-eexanediamine and 1.5 g of FC-128. After the addition by spraying, it is advisable to stir slowly, for example for about 1 hour, to ensure that the reaction goes to completion. Thereafter Ττ ^ ηπ the suspension obtained is allowed to stand until the particles have been collected in an upper phase and the lower phase, consisting of water and soap diamine can be withdrawn for regeneration. The upper phase is then washed 3 to 5 times with deionized water and then 2 to 3 times with aqueous phosphate-bicarbonate buffer, which is the continuous phase in the final suspension. After the final separation, which can be facilitated by gentle centrifugation, possesses

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a suspension which is used to synthesize a comparison liquid by adjusting the equilibrium with a gas mixture which a known COo partial pressure and a known Oo partial pressure owns, is suitable.

When the organic phase enclosed in microcapsules should contain two organic components that are not soluble in one another, the production of the microcapsules takes place according to the invention by suspending one organic component in the other by adding the first-mentioned component sprayed through a nozzle into the second component, and then the suspension obtained is suspended in the aqueous phase by they are sprayed through a nozzle into the aqueous phase. In this way, for example, a suspension of microcapsules, each Perfluorotributylamine suspended in isooctane are prepared.

There were the particularly distinctive features of the invention Reference liquid, namely the oxygen pulse system and the hemoglobin present, if any, appearing colorant, explained. The following are the more common properties of the reference liquid, i.e. its pH buffer properties and their P (COg) buffer properties.

The creation of suitable pH and PCCC ^ buffer mixtures belongs to the state of the art. Ia principle can be used with the Preparation of such buffer solutions the well-known relationship use between carbon dioxide dissolved in water and the pH of the solution:

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-mV η

pH - pK _A -mV η + log.

(a modified Henderson-Hasselbalch equation).,

where pK. the thermodynamic dissociation exponent of carbonic acid, m a constant, η the ionic force, ZHCO ^ I

clear concentration of the hydrogen carbonate ion and / CQ. lare concentration of carbon dioxide is-.

It can be seen from this that the pH of a hydrogen carbonate / carbon dioxide solution is defined and known if the concentrations of hydrogen carbonate and carbon dioxide are known. Such systems have known concentrations of bicarbonate ions and carbon dioxide can be built up in several ways, for example by adding a sodium hydrogen carbonate solution with a COp-containing gas with a known partial pressure balances at COo; But it is also possible to start from sodium carbonate and sodium hydrogen carbonate by '! titration' with the carbon dioxide in situ; and it is also possible to a solution with a known concentration of hydrogen carbonate ions and known carbon dioxide concentration to generate by an acid such as ZCl is added to a hydrogen carbonate or carbonate solution.

These various methods and the corresponding calculations of the parameters of the established system are discussed in detail below.

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The partial pressure of carbon dioxide in a liquid depends on it in the following way of the concentration of dissolved carbon dioxide in the liquid and on the solubility of carbon dioxide in the liquid in question:

where k _{t is} indicative of the solubility of carbon dioxide in the liquid, the solubility being temperature-dependent. A liquid containing a hydrogen carbonate ion / carbon dioxide buffer system (according to the Henderson-Hasselbalch equation above) thus has a fixed P (CO ₂ )

For the purposes of the invention, where it is desired that the reference liquid maintains its stated values for pH and P (COp) to the highest possible degree during storage and handling, it is desirable to take measures which ensure as high as possible that the profit or loss of small amounts of carbon dioxide (during storage and / or handling) lead to the smallest possible change in pH and P (CO ₂ ); this is obtained according to the invention by combining the hydrogen carbonate ion-carbon dioxide buffer system with another pH buffer system, according to the invention preferably with a phosphate buffer system.

This increases the overall buffer effect with regard to the change in pH and P (CO ₂ ) when small amounts of carbon dioxide are increased or decreased. Therefore, preferred comparison liquids according to the invention contain both a phosphate buffer system and a hydrogen carbonate ion / carbon dioxide buffer system. In analogy to the above, these systems can be different

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Be established in a manner, e.g. by equilibrating a phosphate buffer system with carbon dioxide, or by equilibrating a phosphate / carbonate buffer system with CO ₂ by adding an acid, e.g. HCl, to a phosphate / hydrogen carbonate buffer system or by adding a adding such acid to a phosphate / carbonate buffer system. These various methods of establishing such buffer systems are also known in the prior art, but are explained in detail below.

As most of the parameters related to which the reference liquid is used according to the invention for quality control and / or calibration, are temperature-dependent, the quality control should and / or the calibration is preferably carried out at a particular temperature for which the reference liquid is suitable, and the packaging of the reference liquid should mention at which temperature or in which temperature range the stated parameter values apply and / or can be guaranteed with a certain error. In connection with the explanation given below After preparing the reference liquid, it will be understood that either the reference liquid can be prepared at the same temperature and pack it, in which it is to be used later, or the reference liquid can be produced and packaged at a temperature other than the use temperature and then by means of physical / chemical Calculations and / or empirical corrections to the parameter values given for the temperature of use can be determined on the basis of the parameter values for the manufacturing temperature.

As explained above, the reference liquid according to the present Invention be enclosed in a gas-tight container and according to the invention it is desirable that the reference liquid in the essentially free of gas phase in the gas-tight container.

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is closed. The reason for this is that a possible Difference between the temperature to which the specified values of the reference liquid apply and the temperature at which the container with the reference liquid is opened or punched in order to pour the reference liquid into the one to be tested or calibrated Filling the apparatus leads to minor changes in the measured parameters for the reference liquid at the measuring temperature in cases where the reference liquid is enclosed in its container essentially free of gas phase, than in those cases where there is essentially a gas phase together with the reference liquid in the gas-tight container.

In practice, the reference liquid is packaged in the gas-tight container under meticulously controlled conditions of temperature and pressure, and it is important that the container be completely filled with liquid. It is advantageous if the container is flexible to a certain extent, so that no gas phase separation (microbubbles) occurs at variable barometric pressure and temperature during storage and accordingly the reference liquid filled into the container shows a reduced total gas pressure to ensure that under variable temperature conditions takes place during storage, transport and use, for example at temperatures between 0 and 50 ° C, no BiI- ⁴ dung of microbubbles due to over-saturation of dissolved gas.

Suitable containers for packaging the reference liquid according to the invention are, for example, ampoules, cannula ampoules, tubes (Glass cylinders, which are closed at both ends with metalized plastic or rubber stoppers), metal capsules, glass ones Vials and preferably tubes with closed tips or metal foil tubes. The container should be opposite the

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Reference fluid must be chemically inert to avoid any change in the Parameters of the reference liquid due to reactions between the components of the reference liquid and the container material to avoid. Therefore, when the container is made of metal, it is favorable that it be lined with a material which shields the metal from the reference liquid, e.g. with a plastic film such as a polyethylene film.

Therefore, for example, a suitable embodiment of the container is a container made of continuous metal and plastic foil, which has a shape corresponding to the known coffee bags, milk cartons (tetrapacks) and shampoo pillows, or preferably a plastic-laminated metal hose or pipe that is welded together at both ends the plastic film is closed. It is crucial that the material and the shape of the container are selected so that the diffusion through the welds is so low that a loss of Oo and COo during storage, ie during two years of storage, does not exceed the acceptable level change addition; for most practical needs changes in P (COp) and P (Op) of 2% or less, preferably 1% or less, are acceptable. It is also important that the particular material and the thickness of the plastic film are selected so that the amount of CO2 and Op »absorbed in the plastic film does not affect the measurement results, assuming, for example, that the container filled at 37 ° C and opened at about 20 ⁰ C or pierced.

A plastic-laminated metal hose of the type mentioned above can, for example, have an inner layer made of e.g. 50 »m thick polyethylene or BarexS / 210 (PAN C, polyacrylonitrile copolymer) (Lonza), which is used because of its welding properties (in this case the hose can be welded around the circumference getting closed]. If it is desired to use the reference flow

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Polypropylene can be used to stabilize fluid through heat instead of the above mentioned material. The material can accordingly be aluminum foil, which is diffusion-tight. A suitable thickness for the aluminum foil is e.g., 30 µm, which is thicker than the thicknesses of commonly used ones Aluminum foil; the purpose of using greater thicknesses is to reduce the risk of "pinholes". One Another possibility is to use different thinner aluminum foils laminated together. If desired, a nylon layer can be incorporated between the polyethylene and the aluminum foil, e.g. a 15 / im thick nylon layer, to increase the strength of the package, and the outer layer can be nylon with a thickness of preferably about 12 µm or polyester of the same thickness.

Of course, the container should be designed to hold the reference liquid can be filled anaerobically in a blood gas measuring apparatus, i.e. without the admission of atmospheric air, and the prior art has various suitable shapes and fittings.

The exact method that is chosen when preparing the reference liquid depends on the type of system used in the reference liquid and, for example, on the method chosen to establish the pH system (see above). Venn the organic substance which increases the oxygen buffer capacity, is a water-insoluble organic substance with greater solubility for oxygen and the adjustment of the PH-P (COO) -SyStOmS by equilibration of a buffer system with COG, V "nn a a suitable method, for example, be one in which the chemical compounds that are part of the buffer system or systems are precisely balanced and dissolved in a precisely measured amount of deionized water,

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the aqueous and organic phases are mixed and in at the desired weight ratio, aiming for a very fine emulsion, for example with a

-1-2 degree of emulsion of up to between 10 Aim and 10 µm, if necessary, using a suitable emulsifier, the resulting emulsion being transferred to an equilibrium tank, preferably a thermostated tank with stirrer and gas nozzles, the total volume of the tank being 50 to 100% greater than the volume of the liquid whose equilibrium is to be set, the thermostatting is carried out in a suitable manner at 37 ° C + 0.1 ° C and the stirring and metering of the gas is carried out in such a way that a relative rapid equilibrium is ensured, eg a time for equilibrium of at least 16 h (overnight); The equilibrium is established with a gas mixture of precisely set and known partial pressures at COo and Opt, the gas mixture being prepared in a suitable manner according to a method known per se using a COp gas supply, an Op gas supply and an N ₂ gas supply, a pre-humidification system and a pressure regulator is, for example, for the equilibrium setting in the course of 16 h of 200 liters of the comparison liquid, which does not _{contain CO 2} in advance and with an average consumption of 3% of the gas mixture, a gas flow of about 120 l / min is used and the continuous monitoring of the Partial pressures of COp and Op in the gas mixture by means of P (C0p) / P (0p) electrodes, which can be controlled with a reference gas measuring equipment, the reference liquid is filled anaerobically and essentially free of gas phase into the container with the equilibrium set in this way and, if necessary, the sterilization in a manner known per se e, for example by radioactive radiation. If instead of equilibrating with carbon dioxide to establish the P (CO ₂ ) acid is added, such as

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mentioned above, this addition of acid takes place accordingly after equilibrium has been established with Op.

The reference liquids produced and packaged in this way should be carefully checked by taking samples at suitable intervals and using Ρ (00ο) / Ρ (0ρ) measuring devices, pH device, Hb device and total COo / Op " Measuring device measures, the test being carried out for total COpyOg is used to ensure that the COp ^ Og capacity is actually is present. Officially recognized comparator preparations and methods can be used to control the measuring apparatus in the To be calibrated in connection with this check as well as in connection with the final setting of the production parameters.

If the reference liquid according to the invention for quality control is used, it is, as mentioned above, essentially air-free in the blood gas measuring apparatus, preferably on filled in the same way and under the same conditions as the blood samples for which the blood gas measuring apparatus is intended, whereby, of course, the instructions given on the packaging of the reference liquid and the reference liquid are carefully observed flows into the measuring devices consisting of the blood gas measuring apparatus, usually measuring electrodes and relating of the possible hemoglobin device is usually a photometer composed. The reading of the measuring instruments on the reference liquid is recorded, and if the recorded values are in If they deviate to an unacceptable degree from the stated values of the reference fluid, these difficulties must be investigated to avoid errors in the blood measuring apparatus and / or its calibration fluids and / or to find and turn off the method for operating the blood gas measuring apparatus.

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When the reference liquid according to the invention is used to calibrate the blood gas measuring apparatus, it is used in the measuring units of the blood gas measuring apparatus is filled anaerobically, of course those specified on the packaging of the reference liquid Regulations are carefully observed, and the measuring apparatus is adjusted until agreement between the, of the values read on the blood gas measuring device and the values indicated on the reference fluid prevail. When using the Principle of the present invention for calibration, the most suitable way is that one of the blood gas measuring apparatus with two different reference liquids according to the invention, which have different values, which according to the prior art known in the art, and like the above-mentioned radiometer ABL1 apparatus, the blood gas measuring apparatus is for automatic performance equipped with such a calibration, in which case prefabricated and prepackaged reference liquids according to of the invention instead of the reference liquids known from the prior art, which are ready for use in the apparatus itself made to be used.

First there are special regulations for setting up the pH / -P (CO2) system and then examples which illustrate the reference liquid according to the invention. It should be noted that, although already on the basis of the use in the following regulations the calculations listed above empirical constants a very high accuracy of the parameters of the reference liquid can be obtained, the extreme accuracy of the Parameters of a fine setting and adjustment in the special production plant based on partial empirical Constants characteristic of the plant and partially depends on corrections after the control measurements against e.g. officially recognized standards.

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Regulation 1

In a buffer system made up of sodium hydrogen carbonate in equilibrium with a known partial pressure of CO2, can the pH can be calculated according to the Henderson-Hasselbalch equation:

[HCO ~] \ pH = pK + log. i ^

where pK. is the thermodynamic dissociation exponent. To the To calculate the pH it is necessary to use the pK. because of the effect of the Correct ionic strength. This is done in accordance with the Debey-Hückel limit law for activity coefficients. The law is in an * - approximate form used:

pK _A = _P K _A - 0.495

where u is the ionic strength of the electrolytes in the solution and 0.4-95 is an empirically found constant. Together with the introduction of molar concentrations of / EGO ₇ TJ and / 00 ^ 7, the Henderson-Hasselbalch equation is transformed as follows:

PH «pK _A - 0.495 y ^ xx + log [HCO ₃ "] - log

becomes from the equation

[CO ₂ ] = α - P _C02 · ΙΟ- ³

found, whereoid modified Bunsen absorption coefficient is.

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The pH in a 24 χ 10 ~ * M solution of sodium hydrogen carbonate in equilibrium with a gas mixture with a COo partial pressure of 40 mm Hg is 7.53 - If an inert salt (e.g. HaCl) is added for a total ionic strength of 0.21, the pH is 7.38. The following constants that apply to 37 ° C are used:

pK _A = 6.33
<< - 0.032

The regulation applies to 37 ° C.

The pH in a 12 χ 10 ^ M solution of sodium hydrogen carbonate, those in equilibrium with a gas mixture with a COg partial pressure of 80 mm Hg is 6.95

Venn an indifferent salt (eg, NaCl) is added to a total ionic strength of 0.11, the pH is 6.84.

The same constants are used as above.

Regulation 2

Venn a phosphate he puff is equilibrated with Cop, the pH of the buffer change depending on the amount of COP. The following equation arises in a phosphate-hydrogen carbonate mixture system:

HCO ₃ "+ H ₂ PO ₄ " HPO ₄ "" + Co ₂ + H ₂ O ¹

Venn the initial concentrations of HCO, ", H ₂ PO ^" and HPO ₂ , with

'A,' B and C, respectively

be referred to, is the result after the combination:

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where a is the change that balances the system. If carbon dioxide is added until the pressure equals concentration m, another change occurs:

(C + α) + m

The mass action equation for the hydrocarbonate system is:

IH ⁺ ] (A - α)

and for the phosphate system:

[H ⁺ ] (C + α) (B - ο)

If one eliminates <k from the equations, one obtains:

m)

(K ₂ • B) - ([H ⁺ ] • C) IH ⁺ J + K ₀

This leads to the second order equation with respect to which the pH can be calculated as follows:

the end

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pH = - log '

2 (C + A)

D = 4 (C + A) K ₁ * K ₂ * m

is the first acid constant of carbonic acid p is the second acid constant of phosphoric acid A is the molar concentration of hydrogen carbonate B is the molar concentration of dihydrogen phosphate C is the molar concentration of monohydrogen phosphate.

In the calculations, the following constants are used: »6.328 - 0,495V / T (valid at 37 ° C)" = 7,029 - 0,495V ^ T (valid at 37 ⁰ C)

In a buffer with C - B, ^ - 0.1 and a COp partial pressure of 40 mm Hg the pH is 6.59- C = B = 0.025 mol / l.

In a phosphate buffer in which C = 4 B and ^ a * = 0.17 and the COp partial pressure is 80 mm Hg, the pH is 6.90. C = 0.0523 and B - 0.0131 mol / l. The initial concentration of hydrogen carbonate in both solutions is 0.

Regulation 3

The pH can be changed by adding hydrogen carbonate to the phosphate buffer solutions in accordance with regulation 2.

A buffer consisting of C «B« 0.022 M and A = 0.012 M, and is in equilibrium with a gas mixture with a C0 ₂ partial pressure of 80 mm Hg, has a pH of 6.84 (^ u = 0.1 ).

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A buffer consisting of C = 0.047 M, B = 0.012 M and A = 0.022 M. exists and is in equilibrium with a gas mixture with a COp partial pressure of 40 mm Hg, has a pH of 7 »36 (u - 0.17).

Regulation 4

The sodium hydrogen carbonate in the above regulations can be formed by titrating sodium carbonate with carbon dioxide. In this case

CO ₃ + H HCO ₃

CO ₂ + H ₂ OH ⁺ + HCO ₃ "

with the sum:

CO ₂ + H ₂ O + CO ₃ ""'2 HCO ₃

At pH 7 the equilibrium is completely shifted to the right, since less than 0.1 % of the carbonate is unconverted.

Therefore, in regulation 3, the hydrogen carbonate can be replaced by carbonate be replaced at half the concentration, which gives the same pH as calculated in Regulation 3.

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Regulation 5

Regulation 1 can use carbonate instead of hydrogen carbonate be expected. Carbonate is used in half the concentration, see the reaction equilibrium in regulation 4.

Regulation 6

Hydrogen carbonate buffer + acid, e.g. HCl:

+ ICO ₂ ] I »Total concentration of ¹¹ CO ₂ "

When the bicarbonate buffer fails to equilibrate is produced with carbon dioxide, it can e.g. by adding hydrogen st off ions, e.g. from hydrochloric acid, to a hydrogen carbonate solution can be produced. Thus in regulation 1

80 am Hg of P (CO ₂ ) 2.56 χ 10 ~ ⁵ mol CO ₂ A,

formed by adding acid from hydrogen carbonate ions can be:

HCO ₅ "+ H ⁺ - CO ₂ + H ₂ O

For the formation of 2.56 χ 10 " ⁵ moles, 2.56 χ 10" ⁵ moles of H ⁺ , for example in the form of HCl, are required.

This means that (12 + 2.56) χ 10 ~ ⁵ «14.56 χ 10" * ⁵ mol hydrogen carbonate, to which 2.56 χ 10 "* mol HCl and sodium chloride are added up to a total ionic strength of 0.11, in 1 liter of solution gives a pH of 6.84.

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If it is desired to prepare the solution based on carbonate, the following applies:

CO ₃ "+ H ⁺ = HCO ₃ -HCO ₃ " + H ⁺ = CO ₂ + H ₂ O

+ 2H ⁺ = CO ₂ + H ₂ O

1 liter of solution containing (12 + 2.56) χ 10 "'moles of carbonate = 14.56 χ 10 "'moles, including (14.56 + 2.56) χ 10"' moles = 17.12 χ 10 "* moles of hydrogen ions in the form of hydrochloric acid and sodium chloride are added to a total ionic strength of 0.11 also gives a pH of 6.84.

Regulation 7

If the buffers mentioned in Regulation 3 are prepared by adding acid in a closed container, has a buffer, cT = B = 0.022 and A. 14.56 χ 10 "'Morl / 1, mixed with 2.56 χ 10 "'HCl per 1 contains the pH 6.84 and the ionic strength of this solution becomes 0.1025

If the buffer is made from sodium carbonate, the same amount of sodium carbonate is added while the amount of acid is increased to (14.56 χ 2.56) χ 10 "'= 17.12 χ 10"' mol HCl per 1.

A buffer that consists of C = B = 0.022 and sodium carbonate = 14.56 χ 10 "'mol / l mixed with 17.12 χ 10"' mol HCL per 1, has a pH of 6.83 because the ionic strength in this solution is increased to 0.117.

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example 1

Bicarbonate-containing phosphate buffer with a disperse phase of fluorocarbon:

The composition is:

in the aqueous phase:

Disodium hydrogen phosphate 0.047 molal

Potassium dihydrogen phosphate 0.012 molal

Sodium hydrogen carbonate 0.022 molal

Ponceau 4 B 1.7 g / l

The aqueous phase made up 60% of the liquid, with 40% emulsified in the aqueous phase fluorocarbon (perfluorotributylamine) was.

This liquid is suitable for the synthesis of a reference liquid with pH 7.36, P (CO ₂ ) = 40 mm Hg, P (O ₂ ) = 70 mm Hg and Hb = 14 g /% at 37 C, which is done by the liquid is equilibrated with a gas mixture with a CO ^ partial pressure of 40 mm Hg and an _{O 2} partial pressure of 70 mm Hg at a temperature of 37 ° C.

Example 2

A bicarbonate-containing phosphate buffer with a disperse Fluorocarbon phase.

The composition of the aqueous phase is:

Disodium hydrogen phosphate 0.022 molal

Potassium dihydrogen phosphate 0.022 molal

Sodium hydrogen carbonate 0.012 molal

Ponceau 4 B 1.7 g / l

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The aqueous phase makes up 60% of the liquid, while 40% is emulsified fluorocarbon in the aqueous phase (Perfluoromethylcyclohexane) is.

This liquid is suitable for the synthesis of a reference liquid with pH = 6.84, P (CO ₂ ) - 80 mm Hg, P (O ₂ ) - 150 mm Hg and Hb <14 g % at 37 ° C, which is done by the liquid is equilibrated with a gas mixture with a COp partial pressure of 80 mm Hg and an O ₂ partial pressure of 150 mm Hg at 37 ° C.

Example 3

An aqueous phosphate buffer solution containing bicarbonate and containing iron phthalocyanine tetrasulfonic acid.

The composition is:

Disodium hydrogen phosphate 0.022 molal

Ealium dihydrogen phosphate 0.022 molal

Sodium hydrogen carbonate 0.012 molar ferrous phthalocyanine tetraeulfonic acid 2%

Iron (II) phthalocyanine tetrasulfonic acid (Op complex) 1 %

This solution is suitable for the synthesis of a reference liquid with pH 6.84, P (CO ₂ ) = 80 mm Hg, P (O ₂ ) = 1 mm Hg and Hb - 0 g /% at 37 ^° C., which takes place in that one is the solution with a gas mixture with a COP partial pressure of 80 mm Hg and an 0 ₂ partial pressure of 1 mm Hg at 37 ⁰ C to equilibrium.

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Example 4 A bicarbonate-containing phosphate buffer with a disperse Silicone rubber phase The composition of the aqueous phase is: Disodium hydrogen phosphate 0.047 molal Potassium dihydrogen phosphate 0.012 molal Sodium hydrogen carbonate 0.021 molal Ponceau 4 B 1.7 g / l

The aqueous phase constituted 60 % of the liquid, while the remaining 40 % was finely dispersed silicone rubber particles (CAF4 / 60 "Shodorsil").

This liquid is suitable for the synthesis of a reference liquid ■ it pH - 7.36, P (CO ₂ ) «40 mm Hg, P (O ₂ ) ^β 70 mm Hg and Hb = 14 g% at 37 ° C, which is done by that the liquid is equilibrated with a gas mixture with a COg partial pressure of 40 ma Hg and an O ₂ partial pressure of 70 mm Hg at 37 ° C.

In all of the examples given above, instead of _{equilibrating with CO 2} , an acid, for example HCl, can be added in accordance with Regulations 6 and 7.

example 5 A bicarbonate-containing phosphate buffer with a disperse Phase of nylon-coated microparticles of silicone oil. The composition of the aqueous phase is:

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Disodium hydrogen phosphate 0.047 molal

Potassium dihydrogen phosphate 0.012 Mblal

Sodium hydrogen carbonate 0.022 molal

Ponceau 4 E 1.7 g / l

The aqueous phase made up 60 % of the liquid, the remaining 40 % being made up of fluorocarbon emulsified in the aqueous phase (perfluorotributylamine).

The organic phase: microcapsules of silicone oil, with nylon overdrawn.

Pie making was the following:

1.6 g of sebacoyl chloride is dissolved in 80 ml of dimethylsiloxane polymer 200 fluid / 100 from Dow Corning dissolved. 200 is the 3ζτρ, 100 is the Viscosity in centistokes. 35 ml of the mixture is at a Pressure of about 110 atm through a nozzle ia 400 ml of an aqueous Solution containing 3 g of NaOH, 4 g of 1.6 hexanediamine (Fluka) and 15 g Tween ^ 8O (surface-active substance, obtained from Merck-Schuchardt) contains. The mixture is sprayed into the solution below the surface of the water. The aqueous solution is during of spraying and vigorously stirred for 4 minutes thereafter. On the surface of the silicone oil particles, sebacoyl chloride reacts with 1,6-hexanediamine in the aqueous phase to form a nylon membrane.

The particles obtained are centrifuged off and several sharks are washed with the aqueous phase, which is introduced as the continuous phase. The reference liquid obtained contains 40 % aqueous phase and 60 % disperse phase and is suitable for synthesizing a reference liquid with the properties mentioned in Example 1, which is done by equilibrating as in Example 1.

709852/1004

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Example 6

BLn Bicarbonate-containing phosphate buffer with a disperse Phase made of porous, air-containing silicone rubber or rubber. The composition of the aqueous phase is:

Disodium hydrogen phosphate 0.04-7 molal

Potassium dihydrogen phosphate 0.012 molal

Sodium hydrogen carbonate 0.021 molal

Ponceau 4 B 1.7 g / l

The aqueous phase makes up 60% of the liquid, with the remaining 40% being finely divided porous silicone rubber particles (CAF4 / 60 "Ehodorsil") are produced by gave up overpressure during the hardening and then still Relieved the pressure while curing.

This liquid is suitable for the synthesis of a reference liquid with pH 7.36, P (CO ₂ ) 40 mm Hg, P (O ₂ ) 70 mm Hg and Hb 14 g%, each at 37 ° C, which is done by the liquid ■ equilibrates with a gas mixture with a COp partial pressure of 40 mm Hg and an Og partial pressure of 70 mm Hg at 37 ° C.

709852/10 (U

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Claims (1)

Claims Synthetic reference fluid for quality control and / or the calibration of blood gas measuring apparatus, characterized in that it is enclosed in a gas-tight container and in a fixed one Temperature has a known pH, a known carbon dioxide partial pressure, and a known oxygen partial pressure and in addition oxygen, which is reversibly bound to a dispersed organic substance, which has higher solubility for oxygen than water, and optionally contains a coloring component. 2. Reference liquid according to claim 1, characterized in that it is in the gas-tight container substantially is included free of gas phase. 3 «reference liquid according to claim 1 and / or 2, characterized characterized in that it contains a coloring component which has the maximum absorption or a substantial one Contains absorption at about 300 mn. 7098B2 / 10DA ORIGINAL INSPECTED 4. Reference liquid according to one of claims 1 to 3 »characterized in that the dispersed Organic substance is a dissolved organic substance that has a significantly higher solubility for oxygen than Owns water. 5 · reference liquid according to claim 4, characterized in that the dissolved organic substance is monohydric alcohol. 6. Reference liquid according to claim 4 and / or 5> thereby characterized in that the concentration of the dissolved organic substance in the reference liquid 10 to 60%, in particular 20 to 40%, based on the total volume, amounts to. 7 · reference liquid according to one of claims 1 to 6, characterized in that the dispersed organic Substance an emulsified or suspended water-insoluble one is organic matter that has great dissolving power for oxygen owns. 8. reference liquid according to claim 7, characterized in that the emulsified or suspended organic Substance a silicone oil, a silicone rubber or rubber, a fluorocarbon compound or a polymer is the fluorocarbon compound. 9. reference liquid according to claim 7 and / or 8, characterized gekennz ei.chnet that the emulsified or suspended Phase at most 60%, in particular 20 to 50% of the entire volume forms. 709852/1004 2727U0 10. reference liquid according to claim 8 and / or 9 «thereby characterized in that the emulsified organic substance is perfluorotributylamine. 11. Reference liquid according to claim 10, characterized in that the emulsified phase is 30 to 40% of the entire volume. 12. Reference liquid according to one of claims 7 to 11, characterized in that it contains an emulsifying or suspending agent. 13 · reference liquid according to one of claims 1 to 12, characterized in that the organic Substance is a substance on which oxygen is reversible, especially complex, is bound. Reference fluid according to claim 13, characterized in that the oxygen complex-forming organ! see substance is one for which the constant of stability 7. CC of the oxygen complex in the range from 10 ^ to 10- ^/ '' ^/ , in particular 10 * to 10 *. 15 reference liquid according to one of claims 1 to 14, characterized in that the aqueous phase is both a hydrogen carbonate ion-carbon dioxide buffer system as well as an additional buffer system. 16. Reference liquid according to claim 15, characterized in that the additional buffer system is a phosphate buffer system. 709852/1004 17 · Synthetic liquid for use as a reference liquid according to one of claims 1 to 16 or as Intermediate compound for the production of this reference liquid, characterized in that it is an aqueous Phase and contains particles suspended in the aqueous phase, the particles either polymer-coated microcapsules, which contain at least one organic substance, the considerably greater ability to reversibly absorb oxygen as water, or are porous particles of a solid substance. 18. Liquid according to claim 17, characterized in that the aqueous phase has at least one buffer system contains. 19 · Liquid according to claim 18, characterized in that the aqueous phase is both a hydrogen carbonate ion-carbon dioxide-pH buffer system as well as an additional pH buffer system. 20. Liquid according to claim 19, characterized in that the additional buffer system is a phosphate buffer system is. 21. Liquid according to one of claims 17 to 20, characterized in that the microcapsules are a hydrocarbon, a fluorocarbon compound: contain an ester and / or a silicone oil. 22. Liquid according to claim 21, characterized in that g e k β η η draws that the microcapsules contain isooctane. 709852/1 -5- 2727H0 23. A liquid according to .Anspruch 21, characterized in that the microcapsules are perfluorotritmtylamine contain. 24. Liquid according to claim 21, characterized in that the microcapsules are a mixture of isooctane and perfluorotributylamine. 25 liquid according to claim 24, characterized in that the volume ratio of isooctane to perfluorotributylamine in the microcapsules is 5 to 9'Λ to 10 _t, in particular 7 to 8: 3 to 2. 26. Liquid according to claim 25 »characterized in that the volume ratio is approximately 3: 1. 27 · Liquid according to one of claims 17 to 26, characterized in that the polymeric coating of the Microcapsules is nylon. 28. Liquid according to one of claims 17 to 27, characterized in that a coloring component is used with an absorption maximum or a substantial absorption of about 500 nm. 29. Liquid according to one of claims 17 to 28, characterized in that it is in a gas-tight manner Containers enclosed essentially free of gas phase is. 30. Liquid according to one of claims 17 to 29, characterized in that the suspended microcapsules represent at most 80 %, preferably 40 to 70% of the total volume. 709852/1004 2727U0 31. Liquid according to one of claims 17 to 20, characterized in that marked as containing particles of porous silicone rubber or rubber 32. A method for producing a suspension of microcapsules for use as a liquid according to claim 17 or, for use in the preparation of the liquid according to claim 17 *, characterized in that one at least one organic substance, the considerably larger one Ability to reversibly absorb oxygen as water possesses, in an aqueous phase under such conditions suspended that the individual suspended particles are coated with a polymeric material. 33 · Method according to claim 32, characterized in that it is marked e t that the polymeric coating material by interfacial polymerization is created between polymer forming components, one in the organic phase and the other is in the aqueous phase. 34 ·. The method of claim 33 »characterized in that the nylon is formed at the interface where the organic phase is sebacoyl chloride and the aqueous phase contains hexanediamine. 35 · The method according to any one of claims 17 to 3 ^, characterized gekennz ei chnet that the organic phase in the aqueous phase is suspended by being sprayed into the aqueous phase using a nozzle. 36. The method according to claim 35, characterized in that g e k en η that the organic phase contains two organic components which are not soluble in one another, wherein one organic component in the other organic component 709852/1004 -7- 2727U0 component is suspended by spraying the former component into the latter component through a nozzle and then the suspension obtained is suspended in the aqueous phase by spraying the suspension through a nozzle into the aqueous phase. 37 · The method of claim 36, characterized geke η η - 'characterized in that the perfluorotributylamine in isooctane and the suspension obtained is suspended in an aqueous buffer solution. 709852/1004