A Simple Method for Improving the Specificity of the Fluorimetric Determination of Adrenal Corticosteroids in Human Plasma

SUMMARY Extracts of human plasma in ethanolic sulphuric acid contain two groups of fluorogens. The fluorescence of one of these increases linearly with time, while the other gives a constant fluorescence between 8 and 20 min. after extraction into the acid mixture. Measurement of the rate of increase in fluorescence of the plasma extracts permits the proportion of the total fluorescence due to the stable component to be calculated. The component with constant fluorescence probably consists entirely of cortisol and corticosterone. This finding has been used to improve the specificity of a simple method for the determination of adrenal corticosteroids in human plasma. This improved method is described and assessed, and a range of normal values is reported.