A spectrometric study of the fluorescence detection of fecal urobilinoids

Fluorescence spectra of extracts of fecal material, in the presence of zinc ion, display the well-known green fluorescence used in the Schlesinger test for the urobilinoids, together with several other fluorescences. All of these can be demonstrated in a single spectrum by the synchronous fluorescence technique, which, with new extraction conditions, enables the urobilinoid fluorescence to be detected in quantities of human fecal material down to about 50 ng in mass. This represents a reduction on the order of a thousandfold in the detection limit of the original visual technique; selectivity too is greatly increased. The effects caused by a variety of reagents on the fluorescences have been examined. It is shown that in Edelman's version of the test the presence of mercuric ion largely quenches the fluorescence. The synchronous spectra vary considerably between different samples of human feces and between different mammals according to their diet. The specificity of the recommended technique is discussed with reference to the spectra given by other body materials.