DE2727140C2 - Synthetic reference fluid for quality control and / or calibration of blood gas measuring devices - Google Patents

Description

The invention relates to a synthetic reference liquid for quality control and / or calibration » of blood gas measuring apparatus enclosed in a gas-tight container and at a fixed j

Temperature is a known pH, a known carbon dioxide partial pressure, and a known oxygen partial pressure owns.

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 (CO ₂ ) (partial pressure of carbon dioxide) and the concentration of dissolved oxygen in the blood, expressed as P ( O ₂ ) (partial pressure of oxygen) by means of suitable Mcßcloklro- |

which are constructed. A known fully automatic blood gas measuring apparatus, described e.g. B. in U.S. Patent 74 850, also measures the blood hemoglobin content (Hb) at the same time, which is otherwise normally separated eemcsscn will.

From these four central parameters, various derived parameters can be calculated that are derived from are of great importance for assessing the so-called acid-base state of the organism.

The above measurements are all relative measurements, with the unknown sample and standard samples is compared. Hence, the quality of these standards is critical to the quality of measurement of the individual Parameters.

Using manual or semi-automatic blood counters these days is a big technical one Understanding of the operator of the measuring device is necessary in order to obtain measurements of satisfactory quality obtain. The technical training level of the operating personnel can be lower if a fully automatic, self-calibrating apparatus is used, e.g. B. of the type in the aforementioned US-PS 38 74 850 is described; however, this does not remove the need or the desire to improve the measurement quality of the apparatus door including the quality of the standards, calibration fluids, etc. by means of a known reference value check.

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 ₃ 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, ^r such extraordinary ^work!> Mfwand expensive Hxtr3iiUsrüstun ° and Un ° since ewißheit the Herstsllur ^ sverfahrsn technically quite kom ⁿ lizic ~ t

There is interest in e everywhere today ^; nem control system for measuring the values of devices of the type mentioned, since these devices are directly related to the treatment of patients and often under extremely critical circumstances, e.g. During operations.

In the United States of America, Congress has dealt with this problem over the past few years busy and currently the legislation tends to rely on the "blood data supplier" i.e. H. from the head of the laboratory, too demand that he can prove at any time that the measuring equipment used produces reliable data can. For this purpose, he should provide evidence that the measuring apparatus by means of one of the normal calibration system of Apparatus (quality control) independent system was tested.

Therefore today there is also a general need outside of the USA for the possibility of this quality control buy small containers with samples of known composition and great reliability can.

All commercially available blood gas meters must be calibrated frequently, usually every few hours. For this purpose, various calibration liquids are used in the prior art for certain types of apparatus, some of which, e.g. B. pH buffer mixtures, are commercially available in small containers and have a high level of reliability with regard to maintaining the nominal pH value, while the calibration liquids are used to calibrate other parts of the measuring apparatus, e.g. B. the P (CO ₂ ) measuring device and the P (O ₂ ) measuring device, are currently not commercially available in easy-to-handle packs. One-ge technically advanced blood gas analyzers, e.g. For example, the above-mentioned fully automatic BIutgas measuring apparatus using solutions which themselves are calibrated in the apparatus with known gas mixtures to obtain wohldcfinierte values for pH, P (CO ₂₎ and P (O _2), un · ^1, so in The calibration solutions produced in the apparatus, which have well-defined values, are used for calibration within the device without being transferred to separate containers.

US-PS 36 81 255 and Danish patent application 1261/72 describe the use of a single one Calibration liquid with known hydrogen carbonate ion concentration, known partial pressure of carbon dioxide (and accordingly in accordance with the well-known Henderson-Hasselbalch equation known pH) and known partial pressure for oxygen to calibrate the measuring electrodes in blood gas measuring devices, wherein according to said US-PS the calibration liquid in a gas-tight container to the consumer can be delivered.

/ Because of their inclusion in a gas-tight container while maintaining the known parameters, liquids of this type are in principle suitable for quality control and calibration of blood gas measuring devices; in practice, however, using known calibration liquids, in other words, in actually performing the quality control or calibration rl ': rch introduction of the reference liquid into the bleeding gas Mcii.ipparat, it is difficult to meet such precise requirements that can reasonably be expected of a Comparative liquid can be provided for calibration and quality control In particular, the P (O ₂ ) cone brings serious difficulties with it, and with the calibration liquids according to the prior art, which are contained in gas-tight containers, it is not possible under all circumstances to achieve an abandoned control or establishment of the P (O _:) system.

Di; US Pat. No. 3,778,381 describes the use of a fluorocarbon microemulsion. who is able to Absorb large amounts of oxygen and carbon dioxide / u, as a blood substitute in the storage of animals Organs.

The object of the present invention is to provide a synthetic liquid that is easy to handle for quality control and / or calibration of blood gas measuring devices, especially semi-automatic ones a apparatus, to be made available that while maintaining their relevant values with high accuracy and

Reliability can be produced, packed in suitable portion packs, distributed and stored,

* Thus the calibration of the blood gas measuring device simply by inserting a unit amount or a part

»A of which can be carried out into the device without any special manufacture or inspection

Need ring of liquid.

This object is achieved according to the invention by a reference liquid of the type mentioned at the outset, which is characterized by the fact that it is also oxygen, reversibly attached to a dispersed organic substance

'ä

is bound, which has higher solubility for oxygen than water, contains.

The reference liquid according to the invention can also be a colorant or coloring constituent added \

so that they can also be used for quality control / or calibration of the hemoglobin measuring apparatus

is cash. ■ f

In the inventive reference liquid d (as problem of unsatisfactory reliability of the con- t

Trolle or the calibration of the P (O ₂ ) system is solved by the fact that the liquid (which is generally an aqueous si

Liquid) has oxygen reversibly contained in a dispersed organic substance which |

can absorb a larger oxygen ring per unit volume than water in order to increase the O ₂ capacity.

hen this leads to an increased "oxygen buffer capacity", so that j <; the loss or gain of oxygen, %

. j 10, which may occur during handling and measurement, leads to a relatively small change in the |

^M P (O, ι value of the solution, this being the parameter with respect to which the P (Oi) -TeH of the apparatus is to be checked | and / or calibrated.

The term "dispersed organic matter" is intended to both mean an organic substance that is so finely dispersed - ,,

is that a true or colloidal solution of the organic matter in the (usually predominant aqueous |

like to receive liquid, as well as an organic substance in emulsion or in suspension in the prevailing ?

Seeing aqueous liquid mean. This meaning can also be expressed by the expression "dispersed" from f

printed: are, which in the present context the three terms; "solved", "disgusted" and "suspcn- ?,

diert «covers. %

The expression "contained reversibly" is intended to indicate that the oxygen in the organic substance is limited to such f There is such a way that the organic substance provides oxygen under the handling and measuring conditions

or can absorb, so that the organic substance due to its ability to absorb larger amounts of oxygen per |

Unit volume as water, which can increase the oxygen buffer capacity of the reference liquid The f

The expression "contained reversibly" can include cases in which the oxygen is in the organi- · =

see substance dissolved or otherwise predominantly physically bound, as well as such cases in "|

in which the oxygen is mainly chemically bound to or in the organic substance in question, I.

in particular is bound in a complex manner. &

As dissolved organic substances in which the oxygen is dissolved or otherwise mainly physically

is bound. > Inside water-soluble organic compounds are used, which the other parameters in the reference liquid does not have an unfavorable influence and the significantly greater dissolving power for oxygen than have water. It is known that the solubility of oxygen in various water-soluble organic Connections, e.g. B. alcohols, such as. B. ethanol, propanol and tcrt-ButanoI, is considerably larger than in water. In an aqueous solution of such organic compounds, in other words, e.g. B. an aqueous Dissolution of one of the alcohols mentioned is the solubility of oxygen and, accordingly, the oxygen buffer capacity considerably larger than in an aqueous solution without such dissolved organics However, there is also the increase in oxygen solubility, which is necessary to achieve a reliable comparative liquid for calibration or control of the P (Oj) system is desired, is very large and at least about the 5 times, preferably about 10 to 25 times the solubility in water and there so large increases in solubility Difficult to obtain with dissolved organic substances, their use alone does not constitute one preferred embodiment according to the present invention.

When the reference liquid according to the invention as an organic substance that has the oxygen buffer capacity increased, contains 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, which cannot be regarded as essentially water-soluble, is even greater than the oxygen solubility in the above-mentioned water-soluble organic substances. Such water-insoluble organic substances, which have a high dissolving power for oxygen, are, for. B. 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, ie fluorinated, especially perfluorinated hydrocarbons and compounds containing such fluorinated hydrocarbons, as well as their polymers. With such water-insoluble organic compounds which are liquids of lipoid character or solid substances, dispersions which are emulsions of the lipoid-in-water type or suspensions can be produced. For the purposes of the present invention, such systems have the advantage that the high oxygen-dissolving power of the lipoids or solids results in a large oxygen buffer capacity, while the liquid still retains its property as an aqueous solution and therefore still maintains the establishment of a P (CO ₂ ) / Allow pH buffer systems. Particularly preferred reference liquids according to the invention therefore contain oxygen which is dissolved in emulsified or suspended, water-insoluble, organic substances. Of course, it is also possible. Use combinations of water-soluble and water-insoluble organic substances with a large [ oxygen absorption capacity.

In general, the following criteria must be observed when selecting water-insoluble, organic substances ₄ for use as oxygen carriers: r

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

2. the oxygen carrier should have little or no protolytic activity; , "3. the organic phase, which consists of the oxygen carrier * c"> dispersible in an aqueous buffer>;

be to meet the following conditions: i.

a ι high concentration of organic phase (which _{results in a high O 2} capacity of the mixture); yy

b) the mixture should be stable;

c) The density of the mixture should be used for blood gas measuring devices that contain salt bridges and their use depends on the blood being less dense than saline, less than or equal to be 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 remove the material of construction in the Destroy blood gas measuring apparatus);

5. The oxygen carrier should preferably be safe to handle and

6. The oxygen carrier should preferably be a commercially available material and therefore cheap and lightweight to be available.

As an 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 0.98 bar 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 vveisc io% v / v, in Siükönölcn typically 20% v / v v and in isoocian 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 in pure water results in a very large P (O2) difference, while a change in the amount of oxygen e.g. B. in the fluorocarbon compound causes a much smaller P (O _; ) change, and that e.g. B. 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,) 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 is preferably at most 60% of the total volume, in particular 20 to 50%, since the water phase should of course have a sufficient proportion to prevent a deterioration in the quality of the pH measurement to avoid. Therefore, it is clear that in composing the liquid of the invention preferably those emulsified or suspended constituents are chosen which have a particularly high solubility for oxygen, e.g. B. the above fluorocarbon compounds.

As examples of suitable fluorocarbons and compounds containing fluorocarbons, Perfluorotributylamine ((QFqJiN), perfluoromethylcyclohexane and perfluorodimethyldecalin can be mentioned.

Perfluorotribulyhimin is because of its good emulsifying properties and high ability to dissolve oxygen the preferred connection

According to a particular embodiment of the present invention, there is a suspended solid 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. A door for that purpose useful porous silicone rubber can e.g. B. be prepared by before or during vulcanization the silicone rubber creates an overpressure, which is then released during vulcanization. Porous silicone rubber useful for this purpose can also be made by digging into the rubber a volatile silicone rubber nonsolvent, e.g. B. methanol, dispersed and thereafter vulcanizing the silicone rubber and evaporating the volatile substance.

In order to obtain a stable emulsion or suspension, it may be necessary that the invention Reference liquid contains a suitable emulsifying or suspending agent, this agent being any of any Type which, however, does not damage the parameters that are to be determined by means of the reference liquid influenced and a stable emulsion or suspension of the selected organic material results, can be. Suitable emulsifying or suspending agents for this purpose are commercially available. As an example for an emulsifier that is suitable for the preparation of fluorocarbon emulsions in water for the purposes of the invention has been found to be commercially available polyoxypropylene-polyoxyethylene called.

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

Most chemical processes involving oxygen are characterized by being im are essentially irreversible, so that the oxygen-containing compound once formed does not contain oxygen can release more to a significant extent; in other words, following the irreversible procedure formed oxygen-containing compounds are not suitable, the oxygen buffer capacity of the invention Increase reference fluids.

There are reversible oxygen processes, ζ. B. in the blood hemoglobin molecule, which is reversible in considerable Can absorb and release amounts of oxygen, and therefore in principle for the purposes of the present Invention would be excellently suited. However, the hemoglobin molecule is like other biological ones Substances such as B. proteins or protein-containing complexes, outside the organism 'relatively unstable and therefore reference fluids containing hemoglobin or other biological substances, such as. B. Proteins or protein-containing complexes, produced as an oxygen capacity-increasing organic substance have the disadvantage that they are only stable for a relatively short time unless special precautionary measures are taken be taken to ensure their stability, e.g. B. by freezing the reference liquid immediately or shortly after its manufacture and packaging, distribution and storage of the reference liquid in frozen

[Hb] X [O ₂ ]

(c-2BY \ o ₂ ]

J = A- (C- 2βf [O ₂ ! (C - 2βf = c ¹ + Aβ ¹ -A cβ β = K [O ₂ ] C ² + AK [O ₂ ] β ² -AK [Odcβ

Form, addition of suitable stabilizers to prevent chemical degradation and suitable sterilization or adding antibiotics to prevent degradation by microorganisms.

However, they are different, simpler and less sensitive organic compounds than the hemoglobin molecule known that can reversibly bind oxygen complex. As examples of such non-biological

Compounds are in particular organometallic compounds of transition metals, in particular §

Cobalt or iron, in which the metal, usually via a complex bond, to nitrogenous Groups is bound, e.g. B. transition metal complexes with porfyrin-like compounds, such as Eiscn (II) phthalocyanine tetrasulfonic acid. |

For the purposes of the present invention, the organic substance that is chemically, especially granular \

plex, can bind oxygen reversibly, preferably be one that has a suitable position of equilibrium for the reversible oxygen reaction in question, ie an equilibrium position that is similar to that of hemoglobin (the greatest similarity to authentic blood) and / or an equilibrium position that has a Provides maximum oxygen buffer capacity at or around the P (O ₂ ) value to be consumed by the reference liquid.

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

Hb + O ₂ ; > HbO ₂

where Hb is the hemoglobin _{molecule, O 2 is} the oxygen molecule and HbO _{2 is} the oxygen-containing hemoglobin complex.

The solubility of oxygen free form) in the aqueous phase of the blood can reasonably be 1.4 x 10 ^b Mo! Oxygen per liter per 133.3 Pa oxygen partial pressure can be set. Empirically, at an oxygen partial pressure of 3600 Pa, there are equal amounts of hemoglobin in the Hb form and, on the other hand, of hemoglobin in the HbO ₂ form in the blood. At this partial pressure the concentration of dissolved jj is | Oxygen in the water phase of the blood does the following:

[O ₂ ] = 1.4 x 10 "x 27 -3.8 x 10 ⁵
The stability constant K for the oxygen-containing hemoglobin complex is:

w I.

3 Q ν 1

J " W

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 mountain fluid which in this respect comes very close to the properties of blood, ideal compounds are such Compounds are for which the stability constant of their oxygen complex is about 10 ⁴ · ⁵ , e.g. B. in the range from 10 ³ to 10 ⁵ · ⁵ , in particular 10 ⁴ to 10 ⁵ .

Another type of organic compound different from hemoglobin but reversible with Forming oxygen complexes, binds oxygen according to the reaction scheme:

2L + O ₂ <> LO ₂ -L

where L is the ligand that can bind oxygen, and LO ₂ -L is the complex compound in its oxygen- |

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

_K [LO ₂ -L]

[L] ² [O ₂ ] ^S

where [O ₂ ] is the concentration of oxygen free form) which is dissolved in the relevant system. Like the stability constant calculated above for the oxygenated hemoglobin complex, this constant is also temperature-dependent to some extent; however, for the purposes of the present |

Invention, this temperature dependency can usually be neglected. If the concentration of L with -

α and the concentration of L — O ₂ -L are denoted by jS, a + 2β = c (see the reaction scheme) or c = c- 2β, where c is the total concentration of the ligand.

27 27 340

4Λ '[O ₂ U ⁷ -AK [O ₂ ] cβ-ß + K [O ₂ ] c ² = 0
4 A ' \ O ₂ \ ß ² - (4 λ' [O ₂ ] c + I ) β + K [O ₂ ] c ² = ΰ

(4 K [O ₁ ] r + I) (±) / (4 A "[O ₂ ] c · + ΪΤ ^ Ί6 A '[O ₂ ], V [0,] r s

'' 8 A "[0, |

where β, as can be seen from the above, represents the concentration of complex-bound oxygen. The total oxygen concentration in complex systems TO ₂ is:

TO ₂ = [O ₂ ] + ß,

where [O ₂ ] is the concentration of dissolved oxygen and ^ S is the concentration of complex-bound oxygen.

It is crucial for the suitability of the oxygen complex-forming compound 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 reference liquid should have, which means that any loss of small amounts of oxygen from the liquid or any Increase in low levels of oxygen in the liquid, e.g. &. during the handling of the liquid and during a calibration process, the P (O ₂ ) change of the liquid should be as small as possible. Of course, in principle, a high oxygen buffer capacity is achieved when the concentration of the oxygen complex-forming compound in the reference liquid is high; however, the oxygen partial pressure around which the buffer effect has its maximum depends both on the mentioned concentration ais as well as on the size of the above mentioned stability constant A '. If one compiles a reference liquid according to the invention using a compound which forms an oxygen complex, one should therefore preferably choose such a compound as the compound which forms an oxygen complex 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 buffering capacity for the complex system mentioned above can be as follows To be defined:

dß
d log [O ₂ ] ¹

wherein./? and [O ₂ ] have the meanings given above. Therefore, the maximum oxygen buffer capacity is that at which

d (log [O ₂ ]) ²

which in this function is synonymous with

ύβ ² ° ·

log [O ₂ ] = - log K + logjS - 2 log (c - 2β)

d log [O ₂ ] d (c-2ß) ₌ d log [O ₂ ]

d (c-2ß) ate dß

d log [O ₂ ] _ 1 _(loge) _ ₂ _l _{loge (} _ ₂₎

dß β "'c-2ß

d log [O ₂ ] _{= lQge} (± + -J dβ ⁸ VjS c-2β

4 (23) - (2))

Q ² IOg [O ₂ ] _{= logc}

8 y

dß ^{2 6.} , - -s-, r -

It follows from this that = O door

SjS- = (c - 2βΫ = c ² + 4jS- ⁷ - 4cj8
4β ² + 4cβ- c ² = 0

₌ --tc ± V ¹ IOc- + 16c ² ₌ -4c (±) 4cvT

S 8

8 2

On this basis, suitable stability constants for oxygen complexes can be used as an example can be calculated in reference liquids whose oxygen partial thickness is on one of the three values to which should be calibrated frequently, d. H. 66 660 Pa, 19 998 Pa and 6666 Pa. The following relationships apply for this:

1. [O ₂ ] = 6 x 10 " ⁴ mol / l (~ 66660 Pa)

2. [CK] = 2x 10 " ¹ Mol / I (-19 998 Pa)

3. [O ₃ ] = 6 x 10 ⁵ mol / l (~ 6666 Pa)

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, which give a maximum of oxygen buffer capacity for the three mentioned [OJ values:

^{A =}

, _ 0.207 · c 0.207 ■ c

Λ -

(c - 2 ■ 0.207 · cf [O ₂ ] (0.586 · c) ² [O ₂ ]
,. _ 0.603

Λ -

c ■ [O ₂ ]

»■ '° ^J -3χΙ0 <

10 'x 2 x 10 ⁴

. _ 0.603

Λ ι -

10 'χ 6 x 10 ^s

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 at a concentration of 10 mol / l in the reference liquid. It can be seen that the oxygen complex compounds have a considerable oxygen _{buffer capacity (considerably greater steepness of the curve than for H 2} O) in a broad range around the partial pressures mentioned, so that a reduction or addition of a certain amount of oxygen in the range mentioned is only a percentage (relative

small) change in the oxygen partial pressure of the system.

Against the background of the examples given above and FIG. 2 it can be stated that also for Complex compounds containing oxygen according to the reaction scheme

2L + O ₂ ► LO ₂ -L

bind, favorable stability constants are in the range from 10 'to 10 ⁵ - \ in particular 10 ⁴ to 10 ^s .

If the reference liquid according to the invention contains a compound which forms an oxygen complex as the organic compound which increases the oxygen buffer capacity, the concentration of this compound is preferably ^{between 10 4} and 1 mol / l, in particular between 10 ^-3 and 5 × 10 mol / l.

If the reference liquid according to the invention contains a coloring component which is intended to represent hemoglobin and the use of the reference liquid for quality control and / or F.ichur.g of the hemoglobin-measuring part of the blood measuring apparatus is designed, the coloring component is preferably one which has an absorption maximum at or in the Near the isobic point of the system hemoglobin / hemoglobin-oxygen-oxygen-complcx (Hb / HbO ₂ ), that is, near the point at which the molar absorbance caused by Hb has the same size as the molar absorbance caused _{by HbO 2, because a} Blood gas measuring apparatus containing a hemoglobin measuring part is usually equipped with filters such that the absorption of the inputted sample at or in a narrow area around the isobic points, e.g. B. the points at 505 nm is measured. Therefore, dyes with an absorption maximum around 500 nm should be used.

suitable for use in the reference liquid according to the present invention. Examples of such dyes are amaranth, Aüura Red and a chemical Auo dye with the C.I. No. 16 255 (1956), which is the trisodium salt of 1- (4-SuIfO-I-naphthylazo) -2-naphthol-6,8-disulfonic acid is called. The dye used should be present in the liquid in such a concentration that it corresponds to the extinction of human blood, which means a concentration of about 1.7 g / l for the azo dye with the C.I. No. 16255.

3 shows the absorption curve of the azo dye with the C.I. No. 16255.

If the reference liquid according to the invention is in the form of a dispersion, the coloring component also be dissolved in the disperse phase, which gives the reference fluid the appearance of blood. Suitable Dyes for this purpose are e.g. B. Grasol Fast Red BR and Sudan Red 7 B; these two dyes are in Soluble silicone oil.

According to another embodiment of the invention, the dispersed organic substance is polymer-coated Microcapsules present or consist of porous particles of a solid substance.

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. The microcapsules particularly preferably contain isooctane or perfluorotributylamine and very particularly preferably a mixture of isooctane and perfluorotributylamine. When the microcapsules are a mixture Containing isooctane and perfluorotributylamine, it is particularly preferred according to the invention that the volume ratio between isooctane and perfluorotributyiamine 5 to 9: 4 to 10, in particular 7 to 8: 3 to 2 amounts to; A volume ratio of about 3: 1 is particularly preferred, since this is the optimum density of the Mixture results.

The polymer coating of the microcapsules can be any polymer that is in situ at the interface between an organic phase and an aqueous phase either by interfacial polymerization or can be formed by interfacial precipitation. As examples of substances produced by interfacial polymerisation proteins, polyamides (nylon), polyurethane, polyurea, polysulfonamide |

or called polyvinyl ester. Examples of polymers that can be precipitated at the interface are CeI-25 I

lulose nitrate. Protein, polystyrene and »silastic« (the latter compound then vulcanizes |,

must become). According to the invention, the polymer coating of the microcapsules is preferably a non-biological §

cal and non-proteinaceous material, particularly nylon formed in situ. f

The size of the microcapsules is preferably in the range of 1 to 5 µm, and the polymer layer is preferred in the range of 0.03 to 0.06 µm thick.

By including the oxygen buffer capacity-increasing substance in a polymeric coating in the form of microcapsules, first, a more stable suspension is obtained than by emulsifying the same substances and secondly, there is the advantage that substances which increase the oxygen buffer capacity, which otherwise cause difficulties because of their aggressiveness to parts of the blood gas measuring apparatus, e.g. B. 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 or The density of water will be very similar, which will result in any tendency of the disperse phase to differ from the aqueous phase too separate, counteracts The combination of different substances can also improve others Properties, e.g. B. the strength and smoothness of the polymer membrane around the microcapsules. Therefore z. B the addition of carbon tetrachloride to isooctane encapsulated in nylon contributes to softness of nylon membranes and decrease the tendency of the microcapsules to agglomerate.

The preparation of a microcapsule suspension of the type described above takes place by at least an organic substance that has considerably greater reversible oxygen uptake ability than water possesses, suspended in an aqueous phase under such conditions that the individual suspended -15 Particles are coated with a polymeric material. A technique that works in certain respects is similar to this method, is described in the literature ("Semipermeable Aqueous Microcapsules", T M S (hang, F.C. Macintosh, S.G. Mason, Can J. of Physiology and Pharmacology, 44. 115-128 [1966 |. "Artificial Cells". Thomas MingSwi Chang, Charles C. Thomas. Springfield, Illinois, USA 1972). Inö.esen AuI-säi / cn are processes for the production of thin, stable polymer membranes around aqueous microdrops either by interfacial polymerization or by interfacial precipitation. The included aqueous phase could contain enzymes and / or other proteins and was of a continuous aqueous phase separated by means of the semipermeable membranes formed. With the ones described above The two aqueous phases separated in this way served as models for biological / cil walls. Through a such a model facilitated the study of the individual cell functions. A semipermeable Membrane is required between two aqueous phases so that the exchange of water. Salts and small molecules could take place while larger molecules (e.g. enzymes) were being held back The manufacture of the polymer membranes around the aqueous microdroplets was carried out according to the prior art as follows Way:

! The aqueous protein solution (which optionally contained organic diamine) was |

ten soap emulsified in an organic liquid; |

2. by adding a suitable material to the continuous phase, a Polymer membrane formed. The membrane formation was either by interfacial polymerization, the

means by a chemical process, or by interfacial precipitation, that is by a physical process

see pro / e, depending on the lower solubility for a polymer in the interface; |

3. The microcapsules formed were by means of suitable solvents and / or surface-active agents

removed from the organic phase and suspended in an aqueous medium. With a special "

An example was the previously researched interfacial polymerization (Morgan and Kwolek, J. Pol. Sei. 40, 299, 1959) between a water-soluble aliphatic diamine and the solution of a dicarboxylic acid chloride used in an organic solvent.

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

In contrast to the above-mentioned prior art, in the production of the according to the invention usable microcapsule suspensions on a stabilization of a disperse, organic phase in one aqueous medium and a reduction in the rate of diffusion of the liquid phases through the membrane. A typical difference in comparison with the method according to Chang et al. lies in the fact that the procedure for Production of the microcapsule suspensions which can be used according to the invention is an organic phase and not the aqueous phase is finely divided.

In preferred embodiments of the method, the polymeric coating material is obtained by interfacial polymerization formed between polymer-forming components, one of them being in the organic Phase and the other in the aqueous phase. For example, according to a preferred Embodiment nylon is formed in the interface that the organic phase is a sebacoyl chloride and the aqueous phase contains hexanediamine.

The organic phase can be suspended in the aqueous phase in any suitable manner; it will however, it is preferred that the organic phase is suspended in the aqueous phase by using J

a nozzle is sprayed into the aqueous phase. B. Microcapsules with encapsulated isooctane, the | is suspended in an aqueous phase, be prepared by passing through a nozzle isooctane with a content of 10% sebacoyl chloride in an aqueous solution containing hexanediamine and an emulsifier, e.g. B. the potassium salt of fluorinated alkyl carboxylate contains, sprays. For example, on 5 liters of aqueous solution containing 0.1 kg of 1,6-hexanediamine and 1.5 g of the emulsifier, 100 to 500 m! Isooctane with a content of 10% sebacoyl chloride can be introduced. After adding by spraying it is appropriate to stir, e.g. B. to stir slowly for about 1 hour to ensure that the R action is complete. The suspension obtained can then be left to stand until the particles have collected in an upper phase, and the lower phase, which consists of water, diamine and soap, can be drawn off 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 last separation, which can be facilitated by gentle centrifugation, you have a suspension that is used for .Gynthet-. a reference liquid by adjusting the equilibrium with a gas mixture which has a known partial pressure of COj and a known partial pressure of _{O: isl.}
If the organic phase, which is to be enclosed in microcapsules, contains two organic components which are not soluble in one another, the production of the microcapsules is expediently carried out by suspending one organic component in the other by inserting the first-mentioned component through a nozzle the second component sprays, and then the suspension obtained is suspended in the aqueous phase by spraying it through a nozzle into the aqueous phase. On this toilet; ■; can e.g. B. a suspension of microcapsules each containing perfluorotributylamine suspended in isooctane can be prepared.

In the foregoing, the oxygen buffer system of the reference liquid according to the invention and the optionally present hemoglobin-simulating stains are described. In the following, the S

more common properties of the reference liquid, ie its pH buffer properties and its P (CO _? ) buffer properties |

business, explained. ||

The generation of suitable pH and PfCOjl buffer mixtures is state of the art. Basically In the preparation of such buffer solutions, one can use the well-known relationship between dissolved in water Use carbon dioxide and the pH of the solution:

pH - _P K, - _m ^ 7 + log

(a modified Henderson-Hasselbalch equation)

where pK _{A is} the thermodynamic dissociation exponent of carbonic acid, m is a constant, μ is the ionic force. [MCO ₁ ] is the molar concentration of the hydrogen carbonate ion and [CO ₂ ] is the molar concentration of carbon dioxide

This shows 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, containing known concentrations of hydrogen carbonate ions and carbon dioxide, can be constructed in a number of ways, t. B. by equilibrating a sodium hydrogen carbonate solution with a COj-containing gas with a known partial pressure of CO ₃ . But it is also possible to start from sodium carbonate and to form sodium hydrogen carbonate by "titration" with the carbon dioxide in situ. It is also possible to produce a solution with a known hydrogen carbonate ion concentration and a known carbon dioxide concentration by adding an acid such as. B. HCI, to a hydrogen carbonate or a carbonate solution.

These various methods, and the corresponding calculations of the parameters of the functional system, are discussed in detail below.
The partial pressure of carbon dioxide in a liquid depends on the concentration of in the following way

dissolved carbon dioxide in the liquid and on the solubility of carbon dioxide in the question Liquid from:

[COjJ, = k, ■ P (CO ₂ )

where k, 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 (COi).

For the purposes of the invention where it is desired that the reference liquid wedge maintains its specified pH and P (CO ₂ ) values to the greatest possible extent during storage and handling, it is desirable to take measures which ensure, as far as possible, that the Gaining or losing small amounts of carbon dioxide (during storage and / or handling) lead to the smallest possible change in pH and P (CO ₂ ); this is suitably obtained by combining the hydrogen carbonate ion-carbon dioxide buffer system with another pH buffer system, preferably with a phosphate buffer system.

This increases the overall buffer effect with regard to the change in pH as well as P (CO ₃ ) when there is an increase or decrease in carbon dioxide levels. Therefore, preferred reference 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 set up in various ways, e.g. B. by equilibrating a phosphate buffer system with carbon dioxide, or by ·. lan equilibrates a phosphate / carbonate buffer system with CO ₂ by adding an acid, e.g. B. HCl, eircm phosphate / hydrogen carbonate buffer system or by adding such an 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.

Since most of the parameters regarding which the reference liquid! -iit according to the invention for quality control and / or calibration is used, are temperature dependent, the quality control and / or the Calibration should preferably be carried out at a particular temperature for which the reference liquid is suitable, and the packaging of the reference liquid should mention at what temperature or in what temperature range the specified parameter values apply and / or can be guaranteed with a certain error. In connection with the explanation of the production of the reference liquid given below, that either the reference liquid can be produced and packaged at the same temperature which it is to be used later, or the reference liquid at a temperature other than the use temperature can manufacture and pack and then by means of physical / chemical calculations and / or empirical Corrections to the parameter values given for the usage temperature based on the Can determine parameter values for the manufacturing temperature.

As explained above, according to the present invention, the reference liquid must be in a gas-tight container be included, which is desirable. that the reference liquid is essentially free of gas phase is enclosed in the gas-tight container. The reason for this is that there is a possible difference between the temperature to which the specified values of the reference liquid apply and the temperature, in which the container with the reference liquid is opened or punched in order to insert the reference liquid into the Filling in apparatus to be tested or to be calibrated leads to minor changes in the measured parameters for the reference liquid at the measuring temperature in those cases where the reference liquid is in its container essentially free of gas phase is included than in the cases where essentially a gas phase is present 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 with regard to temperature and pressure, and it is important that the container is completely filled with liquid. It is favorable if the container is flexible to some extent. so that no gas phase deposition (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 with variable temperature conditions during storage, transport and use, ι. B. at temperatures between 0 and 50 ⁰ C, no formation of microbubbles takes place due to supersaturation of dissolved gas.

(Suitable containers for packaging the reference liquid for the invention are, for example, ampoules, cannula ampoules, tubular tubes (glass cylinders that are closed on both ends with metalized plastic or rubber stoppers), metal capsules, glass vials and preferably tubes with closed tips or metal foil tubes -he. the container should be chemically inert to the reference liquid, to any change in the parameters of be ugsfiüssigkeit ru avoid / due to reactions between the components of be / ugsflüssigkeit and the container material. therefore, when the container is made of metal, it is favorable that it is lined with a material that shields the metal from the liquid, /. B. m: t a synthetic plastic, such as l B. a polyethylene film. M)

Therefore, for example, a container made of continuous metal and plastic foil is suitable, which has a shape corresponding to a known coffee tea cutlery, milk cartons (tetrapacks) and shampoo pillows, or preferably a metal hose or pipe laminated with plastic, which is welded together at both ends by the plastic foil is locked. It is crucial that the material and the shape of the container are selected so that the diffusion through the weld seams is so low that a loss of O ₂ and CO ₂ during storage, i.e. during two years of storage, does not allow the liquid to pass through change beyond reasonable limits. For most practical needs, changes in P (CO ₂ ) and P (O ₂ ) of 2% or less, preferably 1% or less, are acceptable. It is also important that the special material

and the thickness of the plastic film can be selected so that the amount of COj and O ₂ which is absorbed in the plastic film does not affect the measurement results, e.g. B. assumes that the containers are filled at 37 ° C and opened or punctured at about 20 ° C.

A plastic-laminated metal hose of the above type can, for. B. an inner layer of about 50 μΐη contain strong polyethylene or polyacrylonitrile copolymer, which because of its welding properties is used (in this case the hose can be closed by circumferential welding). If it if it is desired to be able to stabilize the reference liquid by heat, polypropylene can be used in place of the above mentioned material can be used. The material can accordingly be aluminum foil, which is diffusion-tight is. A suitable thickness for the aluminum foil is e.g. B. 30 µm, which is thicker than the usual thicknesses used aluminum foil. The purpose of using greater thickness is to reduce the risk of To reduce "pinholes". Another possibility is that you can create a laminate from different, used thinner aluminum foils. If desired, a nylon layer can be placed between the polyethylene and the aluminum foil are incorporated, e.g. B. a 15 µm thick nylon layer to increase the strength of the packaging / u increase, and the outer layer can be nylon, preferably about 12 µm thick, or polyester be the same thickness.

Of course, the container should be constructed so that the reference liquid in a blood gas measuring apparatus can be filled anaerobically, ie without the admission of atmospheric air, and the prior art has various suitable shapes and fittings.
The special process that is chosen for the production of the reference liquid depends on the type of system and ι used in the fluid. On the method chosen to establish the pH system (see above). If the organic substance that increases the oxygen pulper capacity is a water-insoluble organic substance with greater solubility for oxygen and the setting of the pI-P (CO:! System is made by equilibrating a buffer system with CO ₂ , a suitable method / B be one in which the chemical compounds that are part of the buffer system or the pulver systems are precisely balanced, dissolved in a precisely measured amount of deionized water, the aqueous and organic phases are mixed and emulsified in the desired weight ratio, whereby au A very distant emulsion is targeted, for example with a degree of egg density of up to between 10 μm and 10 ^: am, if necessary using a suitable emulsifier transferred, preferably a thermostated tank with stirrer and gas nozzles, the total volume of the tank being 50 to 100% greater a ls ilas volume of the liquid whose equilibrium is to be established. The thermostatic control is done in an appropriate manner at 37 ° C ± 0.1 ⁰ C and the stirring and metering of the gas is carried out in such a manner that a relatively rapid equilibration is ensured z. B. a time for equilibrium of at least 16 hours (overnight). The equilibrium is established with a gas mixture of precisely set and known partial pressure of CO ₃ and O ₂ , the gas mixture being suitably prepared according to a method known per se using a CO _; -Gas supply, an O _: gas supply and an Nj gas supply, a pre-humidification system and a pressure regulator is produced. For the establishment of equilibrium in the course of 16 h of 200 liters of the reference liquid, which does not _{contain CO 2} in advance, z. B. at an average consumption of 3% of the gas mixture, a gas flow of about 120 l / min is used. The continuous

The partial pressures of CO: and O ₂ in the gas mixture are monitored by means of P (CO?) / P (O;) electrodes, which can be checked with a gas measuring equipment. The reference fluid having so adjusted balance is anaerobically filled and substantially free of gas phase into the container, said gegebcncn ^TaI-1 S in per se known manner, for sterilization. B. by radioactive radiation. If, instead of the establishment of equilibrium with carbon dioxide, _{acid is added to establish the P (CO 2} ), as mentioned above, this acid addition takes place accordingly after the equilibrium with O _{2 has been established} .

The reference liquids prepared and packaged in this way should be carefully checked by taking samples at suitable intervals and using P (CO ₂ ) / P (O ₂ ) measuring devices, pH devices. Hb device and total CO ₂ / O ₂ meter. The test for total CO ₂ / O ₂ is carried out to ensure that the CO _{2/0 2} capacity is actually present. Officially recognized comparison products and methods can be used to calibrate the measuring apparatus in connection with this check as well as in connection with the final setting of the production parameters. When using the reference liquid according to the invention for quality control, it is, as mentioned above, filled into the blood gas measuring apparatus essentially free of air, preferably in the same way and under the same conditions as the blood samples for which the blood gas measuring apparatus is intended. Here, of course, the instructions given on the packaging of the reference liquid are carefully observed, and the reference liquid flows into the measuring device, which consists of the blood gas measuring device, usually measuring electrodes, and, with regard to the possible hemoglobin device, usually a photometer. The reading of the meters on the reference liquid is recorded. If the recorded values deviate to an unacceptable degree from the stated values of the reference liquid, these difficulties must be investigated in order to find and correct errors in the blood measuring apparatus and / or its calibration liquid wedges and / or the process / operation of the blood gas measuring apparatus.

If the fluid according to the invention is used to calibrate the blood gas measuring apparatus, they are filled anaerobically into the measuring units of the blood gas measuring apparatus, of course the ones on the packaging of the Be / ugsflü> igen specified regulations are carefully observed. The measuring apparatus is adjusted until

There is agreement between the values read from the blood gas measuring apparatus and the values indicated on the reference liquid. The most suitable way of calibration is to calibrate the blood gas measuring apparatus with two different reference liquids which have values that differ from one another. In the following, special regulations for setting up the pH / P (CO ₂ ) system and then additional

games that illustrate the reference liquid according to the invention are described. It should be noted that, although already on the basis of the empirical constants mentioned in the following regulations Calculations found a very high accuracy of the parameters of the reference liquid obtained can be, the utmost accuracy of the parameters of a linen setting and adjustment in the special Production plant, the partial empirical constants that are characteristic of the plant, and partly of corrections after the control measurements against z. B. are based on officially recognized standards, depends, "> fig is.

Regulation 1

In a buffer system consisting of sodium hydrogen carbonate in equilibrium with a known partial pressure of CO ₇ , the pH can be calculated according to the Henderson-Hasselbalch equation:

where ρΚ _{Λ is} the thermodynamically ^ dissociation exponent. To calculate the pH it is necessary to correct the pK ,, because of the effect of the icp.ensiärke. This success! according to the Dehey-Hückel limit law for activity coefficients. The law is used in approximate form:

20 ρΚ ' _Λ = pK _A - 0.495 V / 7

where μ is the ionic strength of the electrolytes in the solution and 0.495 is an empirically found constant. Together with the introduction of molar concentrations of [HCOJ] and [CO ₂ ], the Henderson- | Iasselbalch's equation transformed as follows: 25 Ϊ

pH = pK ,, - 0.495 V7 + 10g [HCOJ] - 10g [CO ₂ ]

] [CO ₂ ] becomes from the equation

[CO ₂ ] = a ■ P _{t ()} , · 10 '

found, where σ is the modified Bunsen absorption coefficient.

The pll in a 24 x 10 '-M solution of sodium hydrogen carbonate in equilibrium with a gas i

mixed with a CO ₂ partial pressure of 5333 Pa is 7.53. If an indifferent salt (e.g. NaCl) is used for a 35 l

If a total ionic starch of 0.21 is added, the pH is 7.38. The following constants that apply to 37 ° C, J.

are used: H

pK, = 6.33

a = 0.032 I.

The regulation applies to 37 ° C. §

The pH in a 12X10 '-M solution of sodium hydrogen carbonate, which is in equilibrium with a gas mixture with a CO ₂ partial pressure of 10666 Pa, is 6.95.

If an indifferent salt (e.g. NaCl) is added up to a total ionic strength of 0.11, the value is ph 6.84.

The same constants are used as above.

Regulation 2

When a phosphate buffer is _{equilibrated with CO 2} , the pH of the buffer changes depending on the amount of CO ₂ . The following equation arises in a phosphate-hydrogen carbonate mixture system:

HCO, + H ₂ PO ₄ ι > HPO ₄ + CO ₂ + H ₂ O

If the initial concentrations of HCOJ, H ₂ POJ or HPOJ "with

A, B and C, respectively
the result after mixing is:

(A - a) + (S - α) ΐ » (C + a) + a

where α is the change that brings the system into equilibrium. If carbon dioxide is added until the pressure equals concentration m , another change occurs:

and CO ₂ + H ₂ O t »H ⁺ +

with the sum: CO ₂ + H ₂ O + COf " t * 2HCOr

60

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

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

The mass action equation for the hydrocarbonal system is:

5 [W \ (A - a) _{a K}

in

and door ci? s phosphate system:

ίο [H ⁺ ] (C + a) _{= K}

(B- a) ²

If one eliminates α from the equations, one obtains:

P 15 ([H ⁺ ] -A) - (Kf m) _ (K ₂ ■ B) - ([H ⁺ ] * Q

[H ⁺ ] [H ⁺ ] + K ₂

■ If This leads to the second order equation with respect to [H ⁺ ], from which the pH can be calculated as follows

käiin.

20th

pH = -, og ( Kf m ₊ K ₂ - B- K ₂ - A ^ V (Kf m ₊ K ₂ - B- K ₂ - AY TW_ \ _m

\ 2 (C + A) J

D = 4 (C + A) Kf K ₂ - m

25th

K \ is the first acid constant of carbonic acid

¹ IK ₂ is the second acid constant of phosphoric acid

..jE I A is the molar concentration of hydrogen carbonate

; 'j » B is the molar concentration of dihydrogen phosphate

30 C is the molar concentration of monohydrogen phosphate.

The following constants are used in the calculations: |

PKT = 6.328 to 0.495 V, (valid at 37 ° C)

35

pK ₂ = 7.029 - 0.495 VJ (valid at 37 ° C)

In a buffer with C = B, μ = 0.1 and a CO ₂ partial pressure of 5333 Pa, the pH is 6.59. C = B = 0.025 mol / l. In a phosphate buffer in which C = AB and μ = 0.17 and the CO ₂ partial pressure is 10 666 Pa, the pH is 6.90. 40 C = 0.0523 and B = 0.0131 mol / l. The initial concentration of hydrogen carbonate in both solutions is 0.

Regulation 3

By adding hydrogen carbonate to the phosphate powder solutions in accordance with regulation 2, the pH can be increased to 45 be changed.

A buffer that consists of C = B = 0.022 M and A = 0.012 M and is in equilibrium with a gas mixture with a CO ₂ partial pressure of 10666 Pa has a pH of 6.84 (μ = 0.1).

A buffer that consists of C = 0.047 M, B = 0.012 M and A = 0.022 M and is in equilibrium with a gas mixture with a CO _r partial pressure of 5333 Pa has a pH of 7.36 (μ = 0.17 ).

50

Regulation 4

The sodium hydrogen carbonate in the above regulations can be obtained by titration of sodium carbonate be formed with carbon dioxide. In this case, β applies

55

CO ₃ - + H ⁺ - ₍ » HCOf I.

Regulation 5

Regulation 1 can be expected to use carbonate instead of hydrogen carbonate. Carbonate is used in most cases Concentration used, cf. the reaction equilibrium in procedure 4.

Regulation 6
Hydrogen carbonal powder + acid, e.g. B. HCl:

[I ICOi J + [CO ₂ ] = total concentration of »C0 ₂ «

If the hydrogen carbonate buffer is not prepared by equilibrating with carbon dioxide, can he / .. B. by adding hydrogen ions, z. B. from hydrochloric acid, made into a hydrogen carbonate solution will. Thus in regulation 1

10666 Pa of P (CO ₂ ) 2.56 x 10 " ³ mol CO ₂ / !,
which can be formed from hydrogen carbonate ions by adding acid:

HCO. + IV = CO ₂ + H ₂ O

To form 2.56 x 10 ^l moles, 2.56 Χ 10 "moles of H ⁺ , e.g. in the form of HCl, are required.

This means that (12 + 2.56) X 10 '= 14.56 x 10 "' mol of hydrogen carbonate, to which 2.56 x 10" ³ mol of 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.

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
'$ CO ₃ - + 2H ⁺ = CO ₂ + H ₂ O

1 liter of solution that

(12 + 2.56) x 10 " ³ mol carbonate = 14.56 X 10" ³ mol J5

contains what for

(14.56 + 2.56) X 10 'MoI = 17.12 X 10 " ³ moles of hydrogen ions

.1

l | in the form of hydrochloric acid and sodium chloride up to a total ionic strength of 0.11 are added, results also a pH of 6.84.

Regulation 7

If the buffers mentioned in Regulation 3 are prepared by adding acid in a closed container, a buffer that has C = B = 0.022 and A = 14.56 X 10 " ³ Mo! / L mixed with 2.56 X 10 " ^{Contains 3} HCl per 1, the pH is 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 x 2.56) X 10 ^-3 = 17.12 x 10 " ³ moles of HCl per liter.

A buffer consisting of C = B = 0.022 and sodium carbonate = 14.56 x 10 ^-3 mol / l mixed with 17.12 x 10 " ³ mol iHCl per l has a pH of 6.83, since the ionic strength in this solution is increased to 0.117.

B e i s ρ i e 1 1

Bicarbonate-containing phosphate buffer with a disperse phase of fluorocarbon The composition is in the aqueous phase:

Disodium hydrogen phosphate 0.047 mol

Potassium dihydrogen phosphate 0.012 mol

Sodium hydrogen carbonate 0.022 MoIa!

C.I. Azo dye No. 16255 1.7 g / l

The aqueous phase made up 60% of the liquid, 40% being emulsified fluorocarbon (perfiuorotributylamine) in the aqueous phase.
This liquid is for the synthesis of a reference liquid with pH = 7.36, P (CO ₂ ) = 5333 Pa, P (O ₂ ) = 9333 Pa

and Hb = 14 g /% at 37 ° C, which is done by mixing the liquid with a gas mixture a COj partial pressure of 5333 Pa and an Oi partial pressure of 9333 Pa at a temperature of 37 ° C ins Equilibrium sets.

5 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 mol

Sodium hydrogen carbonate 0.012 molal

C.I. Azo dye No. 16255 1.7 g / l

The aqueous phase forms 60% of the liquid, while 40% is emulsified fluorocarbon water in the aqueous phase. substance (perfluoromethylcyclohexane).

This liquid is used for the synthesis of a reference liquid with pH = 6.84, P (CO ₂ ) = 10666 Pa, P (O ₂ ) = 19998 Pa

and Hb = 14 g / ° o at 37 ° C suitable, which happens that the liquid with a gas mixture with

2u a CO _: partial pressure of 10666 Pa and an O _: partial pressure of 19998 Pa at 37 ° C in equilibrium 3Cw * i.

Example 3

2? A bicarbonate-containing aqueous phosphate buffer solution with a content of

Iron phthalocyanine tetrasulfonic acid

The composition is:

30 disodium hydrogen phosphate 0.022 molal

Potassium Dihydrogen Phosphate 0.022 Molal

Sodium hydrogen carbonate 0.012 mol

Iron (II) phthalocyanine tetrasulfonic acid 2%

Iron (II) phthalocyanine tetrasulfonic acid (OrKomplex) 1%

This solution is suitable for the synthesis of a reference liquid with pH = 6.84, P (CO ₂ ) = 10 666 Pa, P (O ₂ ) = 133.3 Pa and Hb = 0 g /% at 37 ° C, which takes place as a result that the solution is equilibrated with a gas mixture with a CO ₂ partial pressure of 10666 Pa and an O ₂ partial pressure of 133.3 Pa at 37.degree.

Example 4

Hin Bicarbonate-containing phosphate powder with a disperse phase of silicone rubber • 45 The composition of the aqueous phase is:

Disodium hydrogen phosphate 0.047 MoIa!

Potassium dihydrogen phosphate 0.012 molal

Sodium hydrogen carbonate 0.021 moial

50 C.I. azo dye No. 16255 1.7 g / l

The aqueous phase made up 60% of the liquid, while the remaining 40% were finely dispersed silicone gums was.

This liquid is used to synthesize a reference liquid with pH = 7.36, P (CO ₂ ) = 5333 Pa, P (O ₂ ) = 9333 Pa

55 and Hb = 14 g /% at 37 ° C, which is done by equilibrating the liquid with a gas mixture with a COj partial pressure of 5333 Pa and an O ₂ partial pressure of 9333 Pa at 37 ° C.

In all of the examples given above, instead of _{equilibrating with CO 2} , an acid, e.g. B. HCI, according to regulations 6 and 7 to be added.

Example 5

I-in Bicarbonal-containing phosphate buffer with a disperse phase of nylon layers

Microtechnology of silicone oil ο ''

The composition of the aqueous phase is:

Disodium hydrogen phosphate 0.047 molal

Potassium dihydrogen phosphate 0.012 molal

Sodium hydrogen carbonate 0.022 molal

Azo dye of C.L. No. 16 255 1.7 g / 1

The aqueous phase made up 60% of the liquid, the remaining 40% being made up of fluorocarbons emulsified in the aqueous phase (perfluorotributylamine).
The organic phase: microcapsules of silicone oil, coated with nylon.

The production was as follows:

1.6 g of sebacoyl chloride were dissolved in 80 ml of dimethylsiloxane polymer (viscosity 100 cmVs). 35 ml des Mixtures were at a pressure of about 111 bar through a nozzle in 400 ml of an aqueous solution, j |

which contains 3 g of NaOH, 4 g of 1,6 hexanediamine and 15 g of a surfactant, sprayed in ;. That Mixture was sprayed into the solution below the surface of the water. The aqueous solution was during of spraying and vigorously stirred for 4 minutes thereafter. 15 reacted on the surface of the silicone oil particles Sebacoyl chloride with 1,6-hexanediamine in the aqueous phase to form a nylon membrane.

The particles obtained were centrifuged off and washed several times with the aqueous phase, which as the continuous phase was introduced. The reference liquid obtained contained 40% aqueous phase and

uv / / υ UiOfWtO (J ι itaot- uiiu rr αϊ auiu ojrtiLiiOLiaiciCii ciiioi ijCr.ug3iiu3aign.uii mn ucii in uciojjioi χ guimiiiiLuii Liigwix- ixs ^.

Shafts suitable, which was done by setting the equilibrium as in Example 1. ι

Example 6 f

A bicarbonate-containing phosphate buffer with a disperse phase of porous, ",

aerated silicone rubber or rubber ^Λ

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

C.I. Azo dye No. 16255 1.7 g / l

The aqueous phase makes up 60% of the liquid, with the remaining 40% being finely divided porous silicone rubber particles are made by applying overpressure during curing and then released the pressure while it was still hardening.

This liquid is suitable for the synthesis of a reference liquid with pH = 7.36, P (CO ₂ ) 5333 Pa, P (O ₂ ) 9333 Pa and Hb = 14 g /%, in each case at 37 ° C., which takes place in that the liquid is equilibrated with a gas mixture with a CO ₂ partial pressure of 5333 Pa and an O ₂ partial pressure of 9333 Pa at 37.degree.

For this purpose 3 sheets of drawings

Claims (22)

Patent claims: 1. Synthetic reference fluid for quality control and / or calibration of blood gas measuring devices, which is enclosed in a gas-tight container and at a set temperature a known pH, a known carbon dioxide partial pressure, and a known oxygen partial pressure possesses, characterized in that it also has oxygen, which is reversibly dispersed to a organic substance is bound, which has a higher solubility for oxygen than water, contains. 2. Reference liquid according to claim 1, characterized in that the dispersed organic substance is a dissolved organic substance that has a much higher solubility for oxygen than water owns. 3. Reference liquid according to claim 2, characterized in that the dissolved organic substance is a is monohydric alcohol. 4. reference liquid according to claim 2 and / or 3, characterized in that the concentration of dissolved organic substance in the reference liquid 10 to 60%, in particular 20 to 40%, based on the total volume. 5. reference liquid according to claim 1, characterized in that the dispersed organic substance is an emulsified or suspended water-insoluble organic substance that has great solvency for oxygen. f * B ^p - ^ iocftnccioiriMt Narh claim 5 characterized characterizing ° e * that the emul ^ ated or SIIS ⁿ endierte organic substance is a silicone oil, a silicone gum or rubber, a fluorocarbon compound or a polymer is the fluorocarbon compound. 7. reference liquid according to claim 5 and / or 6, characterized in that the emulsified or suspended phase forms a maximum of 60%, in particular 20 to 50% of the total volume. 8. reference liquid according to claim 6 and / or 7, characterized in that the emulsified organic Substance is perfluorotributylamine. 9. reference liquid according to claim 8, characterized in that the emulsified phase 30 to 40% of the entire volume forms. 10. Reference liquid according to one of claims 5 to 9, characterized in that it contains an emulsifying or sun-adding agent . 11. Reference liquid according to one of claims I to 10, characterized in that the organic Substance a substance Lt to which oxygen is bound reversibly, in particular in a complex manner. 12. Reference liquid according to claim 11, characterized in that the oxygen complex-forming organic substance is such. ; he is, for which the stability constant of the oxygen complex is in the range from 10 'to 10 ⁵⁵ , in particular ^{10 4} to 10 ⁵ . 13. Reference liquid according to claim 1, characterized in that the dispersed organic substance is present in polymer-coated microcapsules or from porous particles of a solid substance consists. 14. Reference liquid according to claim 13, characterized in that the contained in the microcapsules Substance a hydrocarbon, a fluorocarbon compound, an ester and / or a silicone oil is. 15. Reference liquid according to claim 14, characterized in that the contained in the microcapsules Substance is isooctane. 16. Reference liquid according to claim 14, characterized in that the contained in the microcapsules Substance is perfluorotributylamine. 17. Reference liquid according to claim 14, characterized in that the contained in the microcapsules Substance is a mixture of isooctane and perfluorotributylamine. 18. Bc / bug liquid according to claim 17, characterized in that the volume ratio of isooctane to perfluorotributylamine in the microcapsules is 5 to 9: 4 to 10, in particular ⁷ to 8: 3 to 2. », 19. Reference liquid according to claim 18, characterized in that the volume ratio is approximately 3: 1. || 50 20. Reference liquid according to one of claims' 6-19, characterized in that the polymer Coating of the microcapsules is nylon. 21. Reference liquid according to any one of claims 13-20, characterized in that the suspended Microcapsules represent at most 80%, preferably 40 to 70% of the total volume. 22. Reference liquid according to claim 13, characterized in that it contains particles of porous silicone rubber or rubber. ΪΙ