Patent ID: 7480032

Claim:
A method for determining the concentration of an analyte in a biological fluid, the method comprising: emitting infrared electromagnetic radiation along an optical path; passing the electromagnetic radiation through a filter, wherein the electromagnetic radiation passing through the filter has at least one of the following wavelengths; about 5.25 μm, about 6.12 μm, about 7.4 m, about 8.0 μm, about 8.45 μm, about 9.25 μm, about 10.4 μm, about 12.2 μm; drawing a biological fluid into an analyzer with a sample extractor; separating out a portion from the biological fluid to create a biological fluid sample, wherein separating comprises separating components of the biological fluid that interfere with optical measurement; passing the biological fluid sample from the sample extractor through a sample supply passage of a sample element into a reagentless sample cell of the sample element; holding the biological fluid sample in the sample cell such that the sample cell is located in the optical path; passing the infrared electromagnetic radiation through the sample cell and the biological fluid sample to a detector; and calculating the concentration of the analyte based on the infrared electromagnetic radiation detected by the detector; wherein the infrared electromagnetic radiation comprises an analyte beam of radiation comprising a spectral band having a center wavelength.