Composition and Method for Analysis of Target Analytes

1 . A method of detecting analytes, comprising the steps of:

providing a mixture containing analytes to be analyzed and microparticles coated with competitive inhibitors of the analytes;

reacting first antibodies with the analytes and the competitive inhibitors under competitive binding conditions; and

measuring the first antibodies bound to the competitive inhibitors using flow cytometry.

2 . The method of claim 1 wherein said first antibodies are labeled with a fluorescent moiety.

3 . The method of claim 2 , wherein said first antibodies are labeled by binding to second antibodies comprising a fluorescent moiety.

4 . The method of claim 1 wherein said measuring step comprises using a microcapillary flow cytometer.

5 . The method of claim 1 wherein the amount of the first antibodies is sufficient to bind about 10 to 100 percent of the competitive inhibitors on the microparticles.

6 . The method of claim 1 wherein the amount of the first antibodies is sufficient to bind about 10 to 75 percent of the competitive inhibitors on the microparticles.

7 . The method of claim 1 wherein said competitive inhibitors have a structure same or substantially same as that of said analytes.

8 . The method of claim 1 wherein said analytes are cell-associated.

9 . The method of claim 1 wherein said analytes are not cell-associated.

10 . The method of claim 1 wherein said analytes comprise hormones, enzymes, chemokines, cytokines, insulin, and signal transduction molecules.

11 . The method of claim 1 wherein said analytes are insulin.

12 . The method of claim 1 wherein said first antibodies comprise monoclonal antibodies.