Counting Non-Aqueous Samples in the TopCount® Microplate Scintillation and Luminescence

The microplate format has become a standard for many biological assays such as high throughput screening for drug discovery and radioimmunoassays. Productivity with these high volume procedures has been limited by the amount of sample handling required and low sample counting throughput. Now, however, microplate assays can be efficiently counted in microplates with the Packard TopCount Microplate Scintillation and Luminescence Counter. This paper summarizes TopCount’s performance for counting samples in organic solvents or bound to the wells of microplates (in-plate assays) using MicroScint-O scintillation cocktail, a special formulation for samples in organic solvents. Results from an enzyme inhibition assay and a microplate immunoassay obtained with TopCount are comparable to those obtained by conventional liquid scintillation and gamma counting.