Reagentless analysis of biological samples by applying mathematical algorithms to smoothed spectra
First Claim
1. A method for determination of concentration of at least one analyte of interest in a biological sample by means of spectroscopic analysis, said method comprising the steps of:
- (a) providing the biological sample in the form of a liquid, said liquid comprising water and at least one analyte dissolved in the water, wherein the water has a spectrum and the at least one analyte has a spectrum different from that of water;
(b) identifying a mathematical function that is substantially similar to a region of a non-smoothed spectrum of said sample over a selected range of the non-smoothed spectrum;
(c) determining a portion of said region of said non-smoothed spectrum having noise that is substantially random;
(d) determining coefficients of said mathematical function that result in a close fit of the function to said selected portion of said non-smoothed spectrum;
(e) calculating at least one of a parameter value of said non-smoothed spectrum at at least one wavelength of said non-smoothed spectrum by means of said coefficients of step (d), wherein said at least one wavelength includes the center of said region of said non-smoothed spectrum;
(f) assigning said at least one calculated value of said non-smoothed spectrum to a wavelength including the center of said selected portion of said region of said non-smoothed spectrum to form at least one point of a smoothed spectrum;
(g) shifting a selected distance in said non-smoothed spectrum and repeating steps (d), (e) and (f) until said smoothed spectrum is formed;
(h) forming a residual spectrum by subtracting each point of said smoothed spectrum at a given wavelength from each point of said non-smoothed spectrum at said given wavelength;
(i) inspecting said residual spectrum to determine if it is random, and if said residual spectrum is not random, repeating steps (c), (d), (e), (f), (g), and (h) to achieve a desired smoothed spectrum; and
(j) after achieving the desired smoothed spectrum, determining the analyte concentration from the desired smoothed spectrum.
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Abstract
Apparatus and method for determining at least one parameter, e. g., concentration, of at least one analyte, e. g., urea, of a biological sample, e. g., urine. A biological sample particularly suitable for the apparatus and method of this invention is urine. In general, spectroscopic measurements can be used to quantify the concentrations of one or more analytes in a biological sample. In order to obtain concentration values of certain analytes, such as hemoglobin and bilirubin, visible light absorption spectroscopy can be used. In order to obtain concentration values of other analytes, such as urea, creatinine, glucose, ketones, and protein, infrared light absorption spectroscopy can be used. The apparatus and method of this invention utilize one or more mathematical techniques to improve the accuracy of measurement of parameters of analytes in a biological sample. The invention also provides an apparatus and method for measuring the refractive index of a sample of biological fluid while making spectroscopic measurements substantially simultaneously.
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Citations
19 Claims
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1. A method for determination of concentration of at least one analyte of interest in a biological sample by means of spectroscopic analysis, said method comprising the steps of:
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(a) providing the biological sample in the form of a liquid, said liquid comprising water and at least one analyte dissolved in the water, wherein the water has a spectrum and the at least one analyte has a spectrum different from that of water; (b) identifying a mathematical function that is substantially similar to a region of a non-smoothed spectrum of said sample over a selected range of the non-smoothed spectrum; (c) determining a portion of said region of said non-smoothed spectrum having noise that is substantially random; (d) determining coefficients of said mathematical function that result in a close fit of the function to said selected portion of said non-smoothed spectrum; (e) calculating at least one of a parameter value of said non-smoothed spectrum at at least one wavelength of said non-smoothed spectrum by means of said coefficients of step (d), wherein said at least one wavelength includes the center of said region of said non-smoothed spectrum; (f) assigning said at least one calculated value of said non-smoothed spectrum to a wavelength including the center of said selected portion of said region of said non-smoothed spectrum to form at least one point of a smoothed spectrum; (g) shifting a selected distance in said non-smoothed spectrum and repeating steps (d), (e) and (f) until said smoothed spectrum is formed; (h) forming a residual spectrum by subtracting each point of said smoothed spectrum at a given wavelength from each point of said non-smoothed spectrum at said given wavelength; (i) inspecting said residual spectrum to determine if it is random, and if said residual spectrum is not random, repeating steps (c), (d), (e), (f), (g), and (h) to achieve a desired smoothed spectrum; and (j) after achieving the desired smoothed spectrum, determining the analyte concentration from the desired smoothed spectrum. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification