Abstract
A method to measure plasma cortisol has been developed using the technique of competitive protein binding or radiostereoassay. Thin layer chromatography developed with methylene chloride/ethanol proved to be the best method for the separation of the different corticosteroids. Separation of the bound steroids was made by adsorption with fuller's earth.
The standard deviation for the zero reference point of the standard curve was 1.93%. No interference was found with the method at the hormone levels measured. The precision of the method was high, and the mean SD at different levels was 14.2%. The coefficient of correlation in water deter minations was r : 0.997. Values in normal plasma were found to be 9.87+3.15 (SD) μ.g of cortisol per 100 ml of plasma.