Determination of nanogram quantities of uranium by pulsed-laser fluorometry

Direct Uranium(VI) and Nitrate Determinations in Nuclear Reprocessing by Time-Resolved Laser-Induced Fluorescence

“…Hence, TRLIF is a very sensitive, selective, and fast method for fluorescent actinides and lanthanides analysis that has been extensively used in various fields of the nuclear fuel cycle (geology, reprocessing, waste storage, medical, environment), mainly for uranium ultratrace analysis − and, more recently, for complexation − and speciation studies − using spectral and temporal features of TRLIF. Moreover, in addition to the previously quoted advantages, determination can be performed remotely with the use of fiber optics and optodes. − Usually, uranium determination is carried out with classical complexing reagents (depending on the matrix) to enhance fluorescence, such as Fluran, phosphoric acid, or sulfuric acid, − using the standard addition method. In these media, the limit of detection is in the subnanogram per liter range (4 × 10 -13 M), and the analysis time is around 10−15 min.…”

Quantitative Analysis of Uranium in Aqueous Solutions Using a Semiconductor Laser-Based Spectroscopic Method

“…Two solutions were prepared as luminescence enhancing reagents using H 3 PO 4 (reagent grade, Sigma-Aldrich) and Na 4 P 2 O 7 ·10H 2 O (reagent grade, Sigma-Aldrich). One was a solution of 0.76 M H 3 PO 4 7 and the other a solution of 0.05 M Na 4 P 2 O 7 in 0.4 M H 3 PO 4 . A volume of 1 mL of the U(VI) sample was mixed with 1 mL of a luminescence enhancing reagent.…”

“…The selective and sensitive detection of uranium (U) is required in various research fields of the nuclear fuel cycle including the preparation of fuel, waste management, and environmental monitoring. − Particular interest has been focused on a quantitative analysis of trace amounts of U in an aqueous medium for the safety assessment of nuclear waste disposal. Spectroscopic methods adopting time-resolved laser-induced fluorescence and laser-induced kinetic phosphorescence measurements have been widely used for the quantitative analysis of hexavalent uranium ions (U(VI)). − These methods are based on the excitation of the U(VI) species by an appropriate laser pulse and the measurement of luminescence intensity with temporal resolution. In particular, a commercially available instrument called a kinetic phosphorescence analyzer (KPA) yields a limit of detection (LOD) of approximately 0.01 parts per billion (ppb) for U(VI) with the aid of a luminescent enhancing reagent such as Uraplex (phosphate-based complex).…”

“…One was a solution of 0.76 M H 3 PO 4 7 and the other a solution of 0.05 M Na 4 P 2 O 7 in 0.4 M H 3 PO 4 . 9 A volume of 1 mL of the U(VI) sample was mixed with 1 mL of a luminescence enhancing reagent. Because the pyrophosphate ions may decompose into phosphate ions, all measurements were performed within 1 day after the sample preparation to avoid the hydrolysis effect of pyrophosphate ions.…”

Uranium determination in groundwater using laser spectroscopy

“…The quenching effect can be minimized by simple dilution of samples with appropriate chemicals such as nitric acid or the addition of strong luminescence-enhancing reagents. Phosphoric acid and polyphosphates are representative reagents that enhance the luminescence intensity of uranium by forming stable complexes with uranium (Kenney-Wallace et al 1981, Zook et al 1981, Geipel 2006, Kumar et al 2008, ASTM 2013b In addition, the luminescence of natural organic matter (NOM) in groundwater also interrupts the precise determination of uranium due to the spectral overlap in the luminescence between NOM and uranium (Zook et al 1981, ASTM 2013b. Figure 1 shows the representative data of time-resolved laser-induced luminescence spectra for the raw groundwater samples listed in Table 1.…”