Methods and reagents are disclosed for preparing a liquid solution of a receptor. The methods comprise combining in a liquid medium the receptor, a chelating agent and a C2-C6 polyol. An amount of the chelating agent and the C2-C6 polyol is sufficient to achieve a stable and active receptor in the liquid solution, which is maintained at a temperature of about 2° C. to about 40° C. The compositions may be employed in assays for the determination of analytes that include receptor-binding analytes.