Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving oxidoreductase
Patent
1999-03-17
2000-01-11
Leary, Louise N.
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving oxidoreductase
435 22, 435 21, 435 15, 435 4, 435975, C12Q 126, C12Q 140, C12Q 142, C12Q 148, C12Q 100
Patent
active
060134674
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a method for the determination of an analyte in a sample containing free haemoglobin by optical measurement with the addition of a bleaching agent to the analytical reagent. This method is particularly suitable for the determination of components of a medical sample such as the parameters .alpha.-amylase, alkaline phosphatase and .gamma.-glutamyl transferase in a blood, serum or plasma sample.
A frequent occurrence when determining components of clinical-diagnostic relevance in blood, serum and plasma samples is that these sample materials contain free haemoglobin i.e. they are haemolytic. This haemolysis can either be due to native haemoglobin released from the erythrocytes or the therapeutic administration of blood substitutes based on non-cellular haemoglobin derivatives.
In many cases the analysis of such samples containing haemoglobin is disturbed or made completely impossible, especially when using photometric methods of determination, mainly due to the spectral properties of haemoglobin or haemoglobin derivatives. This is especially the case when the photometric measurement is carried out at a wavelength at which a strong absorption of haemoglobin takes place for example at wavelengths between ca. 400-420 nm and if at the same time a high content of haemoglobin is present in the sample i.e. usually>500 mg/dl.
The availability of blood substitutes based on haemoglobin derivatives poses the problem of eliminating such analytical interference caused by haemolysis to a much greater extent than previously. After their therapeutic administration, haemoglobin levels of up to ca. 2000 mg/dl can occur in the blood serum or blood plasma and the situation is aggravated by the fact that in this case it is not possible to avoid the presence of free haemoglobin in the sample even by suitable precautionary measures when serum or plasma is obtained from the blood sample.
There is therefore a need for a method which enables photometric determinations of diagnostically important analytes to be carried out without interference even in strongly haemolytic serum or plasma samples containing for example blood substitutes up to concentrations of at least 2000 mg/dl.
The object of the invention was achieved by a method for eliminating or/and reducing interferences that are caused by the presence of free haemoglobin in the determination of an analyte in a sample by optical measurement in which one or several peroxidic compounds are added to the reagent used to determine the analyte or to a part thereof.
The addition according to the invention of peroxidic compounds to the analytical reagent or to one or several partial reagents enables on the one hand an elimination of spectral interference by the haemoglobin present in the sample. On the other hand it was also possible to eliminate interference caused by interactions of haemoglobin with other substances present in the sample.
The reagent which is added to the sample can be in a liquid or solid form. In the case of analyte determinations which are carried out in a liquid phase, it is also preferable to add a liquid reagent to the sample. However, in dry tests the reagent can also be present in a solid form e.g. in the form of impregnated fibres or fleeces.
Inorganic as well as organic peroxides come into consideration as the peroxidic substances. Inorganic peroxidic compounds are preferred such as H.sub.2 O.sub.2, peroxides, perborates, persulfates, peroxodisulfates, percarbonates etc. The peroxidic compounds are particularly preferably selected from the group comprising H.sub.2 O.sub.2 and perborates such as NaBO.sub.2 .times.H.sub.2 O.sub.2 .times.3H.sub.2 O or Na.sub.2 B.sub.4 O.sub.7 .times.H.sub.2 O .sub.2 .times.9H.sub.2 O.
The final concentration of the peroxidic compounds in the test mixture can be varied over a wide range. It is preferably 1-500 mmol/l and particularly preferably 5 -200 mmol/l with reference to the content of O.sub.2.sup.2- in the test mixture.
The addition of peroxidic compounds leads to a rapid bleaching of the colour ca
REFERENCES:
patent: 4252783 (1981-02-01), Kam et al.
patent: 4673654 (1987-06-01), Talmage
patent: 4695552 (1987-09-01), Schmitt
patent: 4978632 (1990-12-01), Mach et al.
International Publication No. WO 90/02202 published Mar. 8, 1990.
International Publication No. WO 86/07462 published Dec. 18, 1986.
Birkner Christian
Siedel Joachim
Town Michael Harold
Boehringer Mannheim GmbH
Leary Louise N.
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