Microplate-Radioluminography, a Substitute for Liquid Scintillation Counting

Abstract

A method alternative to liquid scintillation counting (LSC) for detecting β emitters was developed. The new method involves putting an aqueous ¹⁴C sample onto the flatt-bottomed wells of a polystyrene microplate, drying the sample and determining the radioactivity using radioluminography (RLG). It provides a simple, inexpensive and reliable technique for determining the radioactivity of a few hundred samples simultaneously. ³H can be determined by using a microplate having wells interconnected with shallow vent channels and exposing in helium atmosphere. ³²P can be determined by placing the sample planchettes in shielding adapter made of brass, which prevents each sample from cross-talking. This method was also applied to an off-line counting of ¹⁴C in HPLC eluate. A succession of aliquots of the eluate were collected directly in the wells of microplates and evaporated to dryness. The detection limit was 0.35 Bq per injection. The RLG off-line counting method was utilized to determine [¹⁴C] EPA metabolites formed by rat hepatic microsomes.
Radioluminography, microplate, liquid scintillation counting, β emitters, cross-talk, off-line counting of HPLC eluate, EPA
A substitute for liquid scintillation counting, a simple, inexpensive, sensitive and reliable technique for determining β emitters, applicable to off-line counting of HPLC eluate.