Patent ID: 7670846

Claim:
A method for automatically determining whether a sample liquid to be tested in an optical measuring instrument is a test sample or a control sample; comprising: (a) providing an optical measuring instrument effective for measuring sample liquids for an analyte of interest, wherein each of said sample liquids may be a test sample or a control sample; (b) providing one or more control samples containing a known concentration of said analyte of interest, wherein each of said control samples has been provided with a special optical property that is not present in any of said test samples; (c) using said optical measuring instrument to measure one of said sample liquids for the analyte of interest, wherein the optical measurement additionally evaluates said special optical property; and (d) automatically determining whether the measured sample liquid is a control sample or a test sample by causing the optical measuring instrument to identify the results of the evaluation of said special optical property as being consistent with either a control sample or a test sample; wherein said using said optical measuring instrument comprises using a photometer to measure absorption or remission in the IR range; wherein said special optical property is provided by providing a dye in the control sample; and wherein the dye is an IR dye which does not have a substantial absorption in the wavelength range in which the measurement signal for the analyte of interest is detected.