Determination of low uranium concentrations by laser fluorescence using complexing agents

Time resolved laser fluorescence spectroscopy (TRLFS) was used to determine low uranyl concentrations. An Nd:YAG laser in combination with an optical parametric oscillator was used, excitation wavelength 418 nm. Uranium concentrations were calculated from the emission spectrum pulse numbers within 434- 605 nm in various matrices– NaNO₃, NaCl, KNO₃, Ca(NO₃)₂, CaCl₂ and in Portlandite water (saturated Ca(OH)₂ solution). All solutions were made acidic with HNO₃ and adjusted with a complexant to pH 1. The presence of K⁺ and Ca²⁺ in the nitrate matrix was fond to increase signal intensity whereas the chloride anion reduces both the number of pulses and the afterglow time of the uranyl complex luminescence regardless of the presence of cations of elements from Group IA or IIA. (P.A.)