Direct and Fast Determination of Uranium in Human Urine Samples by Laser-Induced Time-Resolved Spectrofluorometry

The determination of uranium as a toxic (chemically and radioactively) element in human urine is of major medical interest since metabolic models must be established in order to estimate the body burden of uranium in professionally exposed workers. Moreover, nuclear medical regulations require important controls of uranium, with levels determined, from workers' urine samples. Different methods have been and are still used to perform such measurements, namely: fluorescence on pellets, chromatography, counting techniques, neutron activation, and mass spectrometry. However, these different techniques are time consuming, and some of them require bulky equipment. Laser-Induced Time-Resolved Spectrofluorometry (LITRS) is a very sensitive technique for ultratrace determinations of uranium in solution and seemed appropriate for these analyses. This technique is based on laser excitation followed by temporal resolution of the fluorescence signal. The great advantages of this technique, aside from sensitivity, are its triple resolution (i.e., excitation, emission, and life-time) and its rapidity.