Cerenkov Counting Performance on the TopCount Microplate Scintillation and Luminescence Counter

The TopCount Microplate Scintillation and Luminescence Counter has been widely used in biopharmaceutical assays involving both radionuclide and luminescence measurement. A new feature allows the use of TopCount for measuring a high energy beta emitter such as P by Cerenkov counting, a well-known measurement technique that has the main advantage of not requiring the addition of scintillation cocktail. Since cocktail is not required for measurement, there is little or no sample preparation, no chemical quenching, and the cost and time requirement to add cocktail is avoided. These advantages make Cerenkov counting an attractive alternative to liquid scintillation counting of P in microplate based assays. Cerenkov counting performance in the TopCount is documented for a variety of sample matrices and assays. Typical TopCount efficiency, background, and crosstalk data are presented for both liquid and filter based assays. Quench correction for colored samples is also demonstrated.