Quantification Of Uranium Research Articles

Adsorptive stripping voltammetry as a sample pretreatment method for trace uranium determinations by inductively coupled plasma mass spectrometry

Adsorptive stripping voltammetry was investigated as a route for improving trace level quantification of uranium via on-line matrix elimination and analyte preconcentration. On the basis of prior literature reports, propyl gallate was selected as a chelating agent for adsorptive accumulation of uranium (VI) at a mercury thin-film electrode (MTFE). Off-line electrochemical studies indicated that the uranium-propyl gallate (U-PG) complex accumulated (−0.15 V) at a MTFE when the uranium containing sample was mixed (1:1 v/v) with 5 × 10 −5 M PG in 0.05 M sodium acetate buffer (pH 4.5), and could be stripped into 0.05 M sodium acetate or 0.1 M ammonium nitrate, an inductively coupled plasma mass spectrometry (ICP-MS) compatable matrix, by a potential scan to −1.4 V. A thin-layer, flow-by electrochemical cell was placed on-line with ICP-MS and the same basic stripping procedure performed, but 238U was not detected when the stripping potential was applied. Combining a potential step to −1.2 V with injection of 1% HNO 3 did, however, effectively release the uranium to the ICP-MS. Matrix elimination was successful, and 24-fold signal enhancement was achieved with a 10 min accumulation, consuming just 0.8 mL of a 0.5 μg/L uranium solution. Quantitative performance was tested on NASS-4 Open Ocean Seawater (2.68 ± 0.12 μg/L uranium) by using calibration plot and standard addition methods. Nonlinearities, as functions of both analyte concentration and deposition time, were observed and are consistent with saturation of the MTFE, suggesting that the technique is most applicable to ultratrace uranium analysis or appropriately diluted samples.

Alpha-beta discrimination liquid scintillation counting for uranium and its daughters

Advances in liquid scintillation counting (LSC) technologies, such as imporved scintillation cocktail formulations and alpha-beta radiation discrimination, make LSC suitable for applications in uranium process chemistry. Ease of use, low cost, and the huge dynamic range of LSC are distinct advantages for analytical support of actinide processing. All uranium isotopes decay primarily with alpha radiation emission. The immediate short-lived daughters of238U are234Th and234Pa. These nuclides are beta emitters having energy bands that overlap the uranium bands in a liquid scintillation spectrum. The resolution of these overlapping bands by alpha-beta radiation discrimination is useful for uranium quantification and purity verification. Protactinium-234 is a high-energy beta emitter that can be further identified and quantified from it's Cherenkov radiation. Energy spectra were collected on the Packard 2500AB liquid scintillator analyzer for uranyl solutions in diisopropylnaphthalene and pseudocumene based scintillator cocktails. Calibration curves were prepared for nitric, hydrochloric, and sulfuric acid media. Base titrations demonstrated the effect of acid quenching on those system. Ion exchange and water soluble polymer extraction studies are readily followed using liquid scintillation methods.

Adsorption voltammetric techniques for the determination of uranium(VI) with 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone as complex forming reagent

Uranium (VI) can be determined by adsorptive voltammetric techniques, as its chloranilic acid complex, over a wide concentration range. Differential pulse polarography is useful for quantification of uranium between 0.1 and 1.5 mg/l; for the range from 10 to 500 μg/l differential pulse voltammetry and for ultra-trace analysis between 0.024 and 40 μg/l adsorptive stripping voltammetry are preferred. The standard deviation for the 3σ-detection limit of 24 ng/l uranium was found to be 8%. In the trace analysis of metals in aquatic environmental systems by adsorptive stripping voltammetry it is normally necessary to decompose polluted water samples by UV irradiation or microwave digestion. The advantage of the developed method is the fact that no sample pretreatment is necessary.