A simple method for counting antibody bound labelled steroids.

A simple method is described for the counting of tritiated antibody-bound steroid after acidification and extraction into a toluene based scintillant. The resulting count rate is stable and quenching is minimal. The method give improved count rates when compared with methods employing scintillants containing methanol, dioxane, or Triton and compares favourably with methods involving pre-heating of antibody-bound steroid or extraction of free steroids after the addition of ammonium sulphate. A specific antibody for estradiol has been used to illustrate the application of the technique to antibody titration curves and standard curves.