Measuring multiple analytes over a broad range of concentrations using optical diffraction

A method of detecting analytes in a sample in parallel, wherein the concentration of a first analyte is at least 100 times greater than the concentration of a second analyte, said method comprising:

• a). contacting said sample with a device having a first immobilized binding agent to which said first analyte specifically binds and a second immobilized binding agent to which said second analyte specifically binds, wherein each of said binding agents is disposed in a pattern capable of optical diffraction when said first or second analyte binds thereto;
• and
• b). measuring in parallel the binding of the first and second analytes to the first and second immobilized binding agents by the optical diffraction from each of said patterns to detect the presence or absence of the first and second analytes, wherein the binding of the first analyte is measured directly and the binding of the second analyte is indirectly measured using an additional moiety to amplify the optical diffraction.