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Two-phase optical assay

  • US 5,674,699 A
  • Filed: 12/22/1994
  • Issued: 10/07/1997
  • Est. Priority Date: 06/08/1993
  • Status: Expired due to Term
First Claim
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1. A method for measuring one or more analytes in a sample comprisingadding substantially transparent particles to a sample solution;

  • incubating the particles and an affinity reagent with the sample to form a mixture;

    fractionating the mixture to form a particle-rich fraction and a substantially particle-free fraction in fluid contact within a single container, the analyte being partitioned, as a result of binding to said affinity reagent, to concentrate it in one of said fractions;

    optically reading the particle-rich fraction in said container at an analyte-detecting wavelength and a control wavelength;

    optically reading the substantially particle-free fraction in said container at said analyte-detecting and said control wavelength;

    said particle rich and particle free fractions being still in fluid contact in said container at the time of said readings;

    correlating the readings through the particle-rich fraction and the substantially particle-free fraction of the sample with similar readings through a "blank" containing similar particles in a buffer solution, to obtain a quantitative determination of at least one analyte originally present in the sample, said correlating correcting the determination for the optical properties of the particle after absorption of analyte and the optical properties of unbound constituents of the sample which are present in the free volume of the particle-free fraction.

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