Rapid microdetermination of oxygen in 15μl of arterial or venous blood by oxygen electrode in 2-3 min was deviced by using oxygen depleted water (5μg/ml) and ferrous ethylenediamine sulfate as the standard of oxygen. By this technique, saturated oxygen amount and % saturation of oxygen in arterial or venous blood are easily calculated at the same time.
A direct method for the radioimmunoassay of male serum testosterone is described which does not require extraction by organic solvents. Interference from sex hormone binding proteins is removed by adding a gross excess of estradiol to each sample. Separation of bound and free 3H-testosterone is by means of serum dextran coated charcoal. Data indicating the accuracy and reproducibility of this method are presented and the possibility of one-step radioimmunoassay of serum testosterone is discussed.