Calibrating measurements of analyte concentrations in solvents from an electromagnetic spectrum

Abstract

Weak signals scattered from analytes at multiple wavelengths can be summed to illuminate either a single detector or a multiplicity of detectors, offering the possibility of concentrating the spectral energy on a smaller total detector area. In addition, a method is disclosed whereby a calibration of the resulting signal for a given analyte can be obtained by means of measuring the quantity of water in the sample volume and by means of measuring the salinity of the fluid in the sample volume.

1 . A method of calibrating a measurement of a concentration of an analyte dissolved in a solvent within a sample, the method comprising: 
 detecting an amplitude of a signal from a spectral line scattered from the solvent within the sample;    detecting a scattering signal of the analyte dissolved within the sample; and    normalizing the scattering signal of the analyte based on the amplitude of the signal from the spectral line scattered from the solvent.    
   
   
       2 . The method of  claim 1 , further comprising: 
 determining a quantity of solvent within the sample from the amplitude of the spectral line scattered from the solvent.    
   
   
       3 . The method of  claim 2 , further comprising: 
 determining a quantity of analyte within the sample based on the normalized scattering signal of the analyte and the quantity of solvent within the sample, wherein the quantity of analyte within the sample is proportional to the quantity of solvent within the sample.    
   
   
       4 . The method of  claim 1 , wherein the step of detecting an amplitude of a spectral line scattered from the solvent and the step of detecting a scattering signal of the analyte are performed by a single detector.  
   
   
       5 . The method of  claim 1 , further comprising: 
 detecting an amplitude of a signal from a spectral line scattered from the solvent within a reference cell containing a known quantity of solvent; and    determining a quantity of solvent within the sample from the amplitude of the spectral line scattered from the solvent within the sample in comparison to the amplitude of the signal from the spectral line scattered from the solvent within the reference cell having the known quantity of solvent.    
   
   
       6 . The method of  claim 1 , wherein the normalized scattering signal of the analyte is insensitive to changes in sample volume.  
   
   
       7 . The method of  claim 1 , wherein the solvent is water.  
   
   
       8 . The method of  claim 1 , wherein the sample comprises biological material.  
   
   
       9 . The method of  claim 8 , wherein the biological material is human tissue.  
   
   
       10 . The method of  claim 9 , wherein the human tissue comprises blood.  
   
   
       11 . The method of  claim 9 , wherein the human tissue comprises interstitial fluid.  
   
   
       12 . The method of  claim 1 , wherein the analyte is glucose.  
   
   
       13 . An apparatus for calibrating a measurement of a concentration of an analyte dissolved in a solvent within a sample, the apparatus comprising: 
 one or more sources of optical radiation;    a passive optical system that transmits the optical radiation from at least one of the sources to the sample, and collects at least one spectral line from a scattering signal of the analyte dissolved within the sample and collects at least one spectral line from a scattering signal of the solvent within the sample;    at least one detector that detects the scattering signal from the analyte dissolved within the sample and detects the scattering signal from the solvent within the sample; and    a processing device that normalizes the scattering signal of the analyte based on an amplitude of the scattering signal of the solvent within the sample.    
   
   
       14 . The apparatus of  claim 13 , further comprising: 
 a reference cell containing a known quantity of solvent, wherein the passive optical system transmits the optical radiation from at least one of the sources to the reference cell and collects at least one spectral line from a scattering signal of the solvent within the reference cell, wherein at least one detector detects the scattering signal from the solvent within the reference cell, and wherein the processing device determines a quantity of solvent within the sample from the amplitude of the scattering signal from the solvent within the sample in comparison to an amplitude of the scattering signal from the solvent within the reference cell.    
   
   
       15 . The apparatus of  claim 13 , wherein the normalized scattering signal of the analyte is insensitive to changes in sample volume.  
   
   
       16 . The apparatus of  claim 13 , wherein the solvent is water.  
   
   
       17 . The apparatus of  claim 13 , wherein the sample comprises biological material.  
   
   
       18 . The apparatus of  claim 17 , wherein the biological material is human tissue.  
   
   
       19 . The apparatus of  claim 18 , wherein the human tissue comprises blood.  
   
   
       20 . The apparatus of  claim 18 , wherein the human tissue comprises interstitial fluid.  
   
   
       21 . The apparatus of  claim 13 , wherein the analyte is glucose.