A new cocktail for liquid scintillation counting of aqueous radioimmunoassay-samples

The aim of this investigation was to find a scintillation mixture for counting up to 1 ml of plasma. We succeeded in obtaining a mixture of xylene/Triton X-100/mono- and di-butylphosphate, and called it Plasmasol. The properties were ideal for radioimmunoassays of steroids. Good dissolving properties, high counting efficiency, absence of chemiluminescence and a good stability and reproducibility with respect to the disintegrations per minute were achieved. The cost was only 25% of the commercially available ready-to-use liquid scintillation mixtures, with which a comparison was made.