Detection of ultratrace levels of uranium in aqueous samples by laser-induced fluorescence spectrometry

A new method of analysis for ultratrace quantities of ururanium in aqueous samples has been developed with a detection limit of 4 x 10/sup -14/M(10/sup -5/ ppb, 0.01 pg/mL). This detection level is considerably less than the average concentration of 0.1 ppb uranium found in natural groundwaters. The procedure consists of an initial coprecipitation of the solution uranium with calcium fluoride, calcination at 800/sup 0/C, and monitoring the uranium content by laser-induced fluorescence excitation (LIFE). Analytical data using this technique are presented for previously analyzed groundwater samples containing 10/sup -6/-10/sup -7/M uranium. The fluorescence yield dependence on calcination time and temperature and on cation and anion interferences is discussed.