Chemistry: analytical and immunological testing – Composition for standardization – calibration – simulation,...
Reexamination Certificate
2002-05-03
2004-02-10
Wallenhorst, Maureen M. (Department: 1743)
Chemistry: analytical and immunological testing
Composition for standardization, calibration, simulation,...
C436S066000, C436S069000, C702S019000
Reexamination Certificate
active
06689612
ABSTRACT:
FIELD OF INVENTION
This invention relates to the field of reagentless spectrophotometric measurements of analytes in biological and non-biological samples. More specifically, the invention relates to the calibration and monitoring of calibration algorithm(s) of spectrophotometric apparatus used for analyte measurements.
BACKGROUND
Clinical laboratory tests are routinely performed on the serum or plasma of whole blood. In a routine assay, red blood cells (RBC) are separated from plasma by centrifugation, or RBC's and various plasma proteins are separated from serum by clotting prior to centrifugation. Hemoglobin (Hb), light-scattering substances like lipid particles, and bile pigments bilirubin (BR) and biliverdin (BV) are typical blood components which will interfere with and affect spectrophotometric and other blood analytical measurements of blood analytes. Such components are referred to as interferents, and they can be measured by spectrophotometric methods. The presence of such interferents affects the ability to perform tests on the serum or plasma and as such can be said to compromise sample integrity.
Spectrophotometric measurements of blood analytes require proper calibration which can be monitored using quality control materials (QCM). QCM for blood analysis have been described in the prior art. For example U.S. Pat. No. 4,116,336 discloses the use of Amaranth or Ponceau 4 R as calibrators that mimic Hb, but these liquids must be enclosed in a flexible gas-tight container, at sub-atmospheric pressure. There is no teaching that this method is effective under atmospheric conditions. Furthermore, Amaranth and Ponceau 4 R were used separately to mimic Hb.
European Patent No. 0132399 suggests the use of one or more dyes (Acid Rhodamine B, Levafix Brilliant Yellow E-3G and Phloxine B; Phloxine Rhodamine and Atanyl Yellow 4NGL), which mimic the spectral response of whole blood and various levels of Hb in whole blood. There is no teaching of any substance or substances used to mimic an indicator of hemolysis or any analyte in serum or plasma.
WO 87/06343 discloses the use of a combination of Acid Red Dye #27 (CI 16185) and Acid Blue Dye #9 (CI 42090) and also a combination of Ponceau 3R Red Dye (CI 16155) and Acid Blue Dye #9 that simulate samples of whole blood having various levels of the fractions of Hb and of total Hb. There is no teaching of any substance or substances used to simulate an indicator of hemolysis or any analyte in serum or plasma.
Despite the fact that a number of QCM have been identified for various blood components, QCM for reagentless methods for measuring other components such as BR, BV, IL etc. are still needed. Furthermore no reliable method for selecting QCM has been described.
Warren (2001, Clinical Chemistry, Vol 47, No. 6, Supplement 2001) discloses the use of a serum pool for estimating the precision of several calibration algorithms. The use of the serum pool in monitoring the calibration algorithms is not taught.
WO-98/39634 and U.S. Pat. No. 6,268,910 B1 and U.S. Pat. No. 5,846,492 disclose methods for measuring Hb, IL, BR and BV in the presence of Hb, Hb-based blood substitute, IL, BR and BV, methods for measuring Hb-based blood substitute in the presence of Hb, IL, BR and BV, and methods for measuring Hb, IL, BR, BV and MB in the presence of Hb, IL, BR, BV and MB. However, they do not discuss QCM for monitoring calibration for any of the analytes.
It is an object of the present invention to overcome disadvantages of the prior art. This object is met by a combination of the features of the main claims. The sub-claims disclose further advantageous embodiments of the invention.
SUMMARY OF INVENTION
This invention relates to the field of reagentless spectrophotometric measurements of analytes. More specifically, the invention relates to the calibration and monitoring of calibration algorithm(s) of spectrophotometric apparatus used for analyte measurements.
The present invention relates to a method (method A) of monitoring calibration of a spectrophotometirc apparatus comprising one or more calibration algorithms for one or more analytes comprising:
i) measuring absorbance of a quality control material with the apparatus to obtain a measurement, the quality control material exhibiting an absorbance spectra characterized as having a negative slope for a continuous spectral segment from about 5 nm to about 200 nm in length, the spectral segment including a principal calibration wavelength for the one or more analytes;
ii) calculating one or more concentration values from the measurement using the one or more calibration algorithms;
iii) comparing the one or more concentration values with an assigned value given to the quality control material for each of the one or more analytes; and
iv) determining if there is a violation of a pre-established quality control rule, thereby monitoring the one or more calibration algorithms of the apparatus
The present invention also provides the method as just defined (method A), wherein the one or more analytes is one or more analytes in a biological fluid selected from the group consisting of serum, plasma, urine, synovial fluid and cerebrospinal fluid. If the one or more analytes is:
bilirubin, then in the step of measuring (step i)) the spectral segment is selected from wavelengths of the absorbance spectra of from about 450 nm to about 600 nm;
an indicator of hemolysis, then in the step of measuring (step i)) the spectral segment is selected from wavelengths of the absorbance spectra of from about 550 nm to about 650 nm, and the indicator of hemolysis selected from the group consisting of total Hb, Oxy-Hb, and “total Hb minus met-Hb”;
a hemoglobin-based blood substitute, then in the step of measuring (step i)) the spectral segment is selected from wavelengths of the absorbance spectra of from about 550 nm to about 700 nm;
met-hemoglobin, then in the step of measuring (step i)) the spectral segment is selected from wavelengths of the absorbance spectra of from about 610 nm to about 690 nm;
methylene blue, the in the step of measuring (step i)) the spectral segment is selected from wavelengths of the absorbance spectra of from about 650 nm to about 750 nm;
biliverdin, the in the step of measuring (step i)) the spectral segment is selected from wavelengths of the absorbance spectra of from about 650 run to about 800 nm.
The present invention also pertains to the method as just described (method A) wherein the quality control material comprises one or more substances selected from the group consisting of a dye, copper sulfate, total Hb, Oxy-Hb, carboxy-Hb, “total Hb minus met-Hb”, cyanmet-Hb, a Hb-based blood substitute, Intralipid and a perflurocarbon-like blood substitute. Furthermore, the absorbance spectra of the one or more substances may be altered by adding a modifier. Preferably the modifier causes a spectral shift in the absorbance spectra. The modifer may be selected from the group consisting of a polymer, a protein, amaranth, and a combination thereof.
The present invention also relates to a method of monitoring calibration of a spectrophotometric apparatus comprising one or more calibration algorithms for a perflurocarbon-like blood substitute, turbidity, or a combination thereof, comprising:
i) measuring absorbance of a quality control material with the apparatus to obtain a measurement, the quality control material exhibiting an absorbance spectra from about 700 nm to about 1100 nm;
ii) calculating one or more concentration values from the measurement using the one or more calibration algorithms;
iii) comparing the one or more concentration values with an assigned value given to the quality control material for each of the perflurocarbon-like blood substitute, turbidity, or a combination thereof; and
iv) determining if there is a violation of a pre-established quality control rule, thereby monitoring the one or more calibration algorithms of the apparatus
The present invention also provides a method (method B) for determining the concentration of one or more analytes in a sample in
Katten Muchin Zavis & Rosenman
Spectromedical Inc.
Wallenhorst Maureen M.
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