Determination of Tritiated Dexamethasone in Rat Liver and Muscle: Comparison of Two Sample Preparation Techniques, Combustion and Solubilization, Prior to Liquid Scintillation Counting

Abstract

Rats were injected intramuscularly with 20 μCi/kg [3H]dexamethasone, which is a synthetic therapeutic glucocorticoid. After 2 h, the rats were sacrificed, and liver and muscle tissues were taken for assay. 3H radioactivity measurements were performed in a liquid scintillation counter. The objective of this study was to compare two sample preparation techniques, namely, alkaline solubilization versus dry combustion, to release the incorporated radioactivity quantitatively from rat liver and muscle; sample combustion has a recovery of 99 ± 1.0%. In addition, the effect of bleaching the samples with hydrogen peroxide was evaluated and quench correction curves were established. The current data demonstrated that the efficiencies of both methods were similar in the measurement of [3H]dexamethasone incorporated in rat liver and muscle tissues. For muscle, differences in disintegrations per minute (dpm) reached only 0.18%; for liver, the score was 0.78%. In conclusion, knowledge of the total radioactivity presen...