ABSTRACT
The most widely used method for radioactivity analysis is liquid scintillation counting. Nonbiological samples are comparatively simple and therefore their incorporation into a scintillation cocktail is much more straightforward. The components present in biological samples require either specialist cocktails or modified sample preparation techniques. Most biological sample preparations suffer from at least some degree of quench, and if purely machine counts are used, then this is likely to lead to serious errors. Since the purpose of sample preparation is to dissolve biological samples, some aggressive reagents have to be used. Most of the sample preparation problems occur with blood samples from smaller animals such as rats and mice. Alternative sample preparation methods include sample combustion and solubi-lization. Some form of destructive sample preparation is therefore necessary with tissues, in order to release or convert the radioactivity into a form that will mix with the scintillation cocktail.
