Advances in the use of fluorimetry in inorganic analysis

The applications are discussed of lasers in time-differentiated fluorimetry, and the exceptional selectivity and sensitivity are shown of the method (of the order of fg/ml). The method can be used in determining uranium in a 10% solution of H3PO4 or HF within 0.1 mg/ml and 10 pg/ml with an accuracy of ±(1-8)%, this thanks to the long life of UO22+ luminescence. A new method is described of measuring luminescence of crystalline luminous materials, SEPIL (Selective Excitation of Probe Ion Luminescence), based on splitting the electron level of incomplete f orbitals into a series of levels by the action of the crystal field. SEPIL allows determining 10 fg/ml of uranium in drinking water. The detection limit for lanthanides is 0.4 pg/ml. (J.C.)