An Improved Method for the Fluorimetric Determination of 5‐Hydroxytryptamine in Tissues

Abstract

ABSTRACT In the method described where the fluorescence of 5‐hydroxytryptamine (5‐HT) is read in 3 N HCl, tissue blanks are produced by means of UV‐irradiation in the presence of potassium ferricyanide. This treatment destroys only the 5‐HT but no other substance fluorescing at 295/545 m μ . With this new type of blank and by reduction of the volumes of the eluate and the reagents the sensitivity of the method is improved so that 25 ng (1 ng = 10 ‐9 g) in an extract can be demonstrated and 50 ng determined quantitatively. The stability of 5‐HT in 0.4 N perchloric acid extract is increased by adjustment of the pH almost to neutrality and by addition of ascorbic acid and ethylenediamine tetraacetate. The recovery and reproducibility are satisfactory.