[en] Individual particles with diameters of the order of 5 μm have been analyzed with the PIXE as well as the electron microprobe technique and with a special kind of XRF technique. The sample in the form of a small calcium fluoride crystal was mounted on a carbon foil and excited with protons or electrons, or in the XRF mode with X-rays generated in a primary target by the electron beam of the electron microprobe. In the last case the X-rays generated in the primary target were prevented from reaching the detector by means of a small metal shield mounted on the carbon foil and leaving the calcium fluoride particle unshielded. The three techniques have been compared with respect to the detection limit for small amounts of uranium in CaF₂ particles. (orig.)