Pathlength-independent methods for optically determining material composition
First Claim
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1. A method of measuring concentration of glucose in a fluid sample comprising, in no particular order:
- providing a cuvette;
providing a source of electromagnetic radiation that emits radiation through the cuvette;
providing a detector that detects radiation emitted from the source, the detection occurring after the radiation has traveled a pathlength, traveling a pathlength comprising passing at least through the cuvette;
inserting saline reference fluid into the cuvette;
using the saline reference fluid to determine the pathlength;
using the pathlength to determine the correct reference spectrum for sample water absorbance, and calculating the correct reference spectrum for sample water absorbance or selecting the correct reference spectrum for sample water absorbance from among a plurality of stored reference spectra;
using the pathlength to determine the correct reference spectrum for sample protein absorbance, and calculating the correct reference spectrum for sample protein absorbance or selecting the correct reference spectrum for sample protein absorbance from among a plurality of stored reference spectra;
inserting a fluid sample into the cuvette;
emitting a range of wavelengths from the source through the cuvette and the fluid sample;
obtaining total sample absorbance data by measuring, through the range of wavelengths, the amount of radiation that reaches the detector;
subtracting the correct reference water and protein absorbance spectra from the total sample absorbance data; and
using the remaining absorbance spectrum, after the correct reference water and protein absorbance spectra have been subtracted, to determine concentration of glucose in the fluid sample.
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Abstract
A method uses spectroscopy to determine an analyte concentration in a sample. The method includes producing an absorbance spectrum of the sample. The method further includes shifting the absorbance spectrum to zero in a wavelength region. The method further includes subtracting a water or other substance contribution from the absorbance spectrum.
130 Citations
45 Claims
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1. A method of measuring concentration of glucose in a fluid sample comprising, in no particular order:
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providing a cuvette; providing a source of electromagnetic radiation that emits radiation through the cuvette; providing a detector that detects radiation emitted from the source, the detection occurring after the radiation has traveled a pathlength, traveling a pathlength comprising passing at least through the cuvette; inserting saline reference fluid into the cuvette; using the saline reference fluid to determine the pathlength; using the pathlength to determine the correct reference spectrum for sample water absorbance, and calculating the correct reference spectrum for sample water absorbance or selecting the correct reference spectrum for sample water absorbance from among a plurality of stored reference spectra; using the pathlength to determine the correct reference spectrum for sample protein absorbance, and calculating the correct reference spectrum for sample protein absorbance or selecting the correct reference spectrum for sample protein absorbance from among a plurality of stored reference spectra; inserting a fluid sample into the cuvette; emitting a range of wavelengths from the source through the cuvette and the fluid sample; obtaining total sample absorbance data by measuring, through the range of wavelengths, the amount of radiation that reaches the detector; subtracting the correct reference water and protein absorbance spectra from the total sample absorbance data; and using the remaining absorbance spectrum, after the correct reference water and protein absorbance spectra have been subtracted, to determine concentration of glucose in the fluid sample. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of measuring concentration of an analyte in a fluid sample comprising, in no particular order:
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providing a sample container; providing a source of electromagnetic radiation that emits radiation through the sample container; providing a detector of electromagnetic radiation that detects radiation emitted from the source after the radiation has traveled a pathlength, traveling a path length comprising passing at least through the sample container; inserting a reference fluid into the sample container; determining the pathlength; using the pathlength to determine the correct reference spectrum for sample water absorbance; inserting a fluid sample into the sample container; emitting at least one wavelength from the source through the sample container and the fluid sample; obtaining composite sample data by measuring the amount of radiation of the at least one wavelength that reaches the detector; subtracting the correct water absorbance reference spectrum from the composite sample data; and using the remaining absorbance spectrum, after the correct water absorbance reference spectrum has been subtracted, to determine concentration of the analyte in the fluid sample. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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41. A method of measuring concentration of an analyte in a fluid sample comprising, in no particular order:
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providing a sample container; providing a source of electromagnetic radiation that emits radiation through the sample container; providing a detector of electromagnetic radiation that detects radiation emitted from the source after the radiation has traveled a pathlength, traveling a pathlength comprising passing at least through the sample container; inserting a reference fluid into the sample container; determining the pathlength; using the pathlength to determine the correct reference spectrum for sample water absorbance, the reference spectrum for sample water absorbance comprising at least one absorbance value at or near a reference water wavelength; inserting a fluid sample into the sample container; emitting at least one wavelength from the source through the sample container and the fluid sample; obtaining composite sample data by measuring the amount of the at least one wavelength of radiation that reaches the detector; and subtracting the correct water absorbance reference spectrum from the composite sample data; and using the remaining absorbance spectrum, after the correct water absorbance reference spectrum has been subtracted, to determine concentration of the analyte in the fluid sample. - View Dependent Claims (42, 43, 44, 45)
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Specification