Determination of uranium by flow injection inductively coupled plasma mass spectrometry

Hyphenation of capillary electrophoresis with MC-ICP-MS - A novel tool for uranium age dating

Capillary electrophoresis (CE) was hyphenated to multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) to determine the model age of a highly enriched uranium (HEU) sample using the ²³⁴U/²³⁰Th radiochronometer. The use of hydroxymethylbutyric acid (HMBA) as the CE electrolyte was investigated, and a complexation stacking method was developed to increase the thorium signal obtained. The age of the material was determined by measuring the ²³⁰Th content of the HEU sample using isotope dilution in conjunction with the CE-MC-ICP-MS protocol. The CE-MC-ICP-MS protocol and a standard offline protocol using gravitational chromatography both gave results in accordance within uncertainties with the production date of the HEU sample (March 1965). Liquid waste production was only of a few microliters with the use of CE. The hyphenation of CE with MC-ICP-MS render the measurement of the age of the HEU material in less than one day possible. Obtaining results in a timely fashion is of particular importance for nuclear forensics studies.

An automated system for preconcentration on imprinted polymer and laser diode spectrometric determination of uranium in mineral water samples

A study, where uranium was online enriched and laser diode spectrometry was determined, was performed with some bottled mineral water samples. A uranium-imprinted polymer (PMDU) was synthesized and characterized for preparation of a specific adsorbent of UO₂²⁺ cations. The homemade system preconcentrated uranium in PMDU resin and determined using an Arsenazo III complex at 650 nm in a combined laser diode spectrometer. All analytical parameters of the system were optimized at 5.5 of the retention pH, 6.0 N HClO₄ of eluent concentration, 0.05% of Arsenazo III complex, and a 40 mm coil length. The effect of interferent ions was also investigated and LOD and LOQ values were found to be 0.54 and 1.80 ng mL^-1 respectively. Sample throughput was 12 h^-1, the preconcentration factor was 50, and RSD% value was 1.1. Certified reference materials of TMDA 52.3 and TMDA 62.2 were quantitatively analyzed and the proposed method was successfully applied to the bottled mineral water samples.

Laboratory automation based on flow techniques

Flow techniques have undoubtedly aroused special interest in relation to many other automatic methodologies of analysis. Ever since segmented flow analysis (SFA) was developed by Skeggs in 1957, flow techniques have been in continuous evolution toward new develop-ments. There is no solid argument in favor of using any particular flow technique separately; rather, substantial advantages can be derived from their combination. Since flow-based methods are nonseparative tools, the advantages of combining flow techniques with separation techniques are noteworthy. High selectivity can be achieved by coupling them with liquid chromatography (LC), gas chromatography (GC), solid-phase extraction (SPE), or capillary electrophoresis (CE). Thus, a detailed description of flow techniques, their evolution, their hyphenation advantages, and a critical comparison between current developed methods exploiting flow techniques aimed at solving present analytical needs are reviewed in this article.

Indirect Determination of Uranium by the On-line Reduction and Fluorimetric Detection of Cerium(III)

A novel flow injection method has been developed for the indirect determination of uranium by the on-line reduction and subsequent fluorimetric detection of cerium(III). A sample solution containing uranium(VI), prepared as a sulfuric acid solution, was injected into a sulfuric acid carrier solution and passed through a column packed with metal bismuth to reduce uranium(VI) to uranium(IV). The sample solution was merged with a cerium(IV) solution to oxidize uranium(IV) to uranium(VI) and the cerium(III) generated was then monitored fluorimetricaly. The present method is free from interference from zirconium, lanthanides, and thorium, and has been successfully applied to the determination of uranium in monazite coupled with an anion-exchange separation in a sulfuric acid medium to eliminate iron(III). The sample throughput was 25 per hour and the lowest detectable concentration was 0.0042 mg l(-1).

Isotopic measurements of uranium using inductively coupled plasma cavity ringdown spectroscopy

Inductively coupled plasma cavity ringdown spectroscopy (ICP-CRDS) is applied to isotopic measurements of uranium. We have successfully obtained the isotopic-resolved spectra of uranium at three different atomic/ionic transition lines, 286.57, 358.49, and 409.01 nm. Of the three lines, the largest isotope shift of approximately 9 pm was measured at the 286.57 ionic line. Isotopic-resolved spectra were recorded in ratio of 1:1 (235U/238U, 2.5 micrograms/mL) and at the natural abundance ratio of 0.714% (235U/238U, 1.25 micrograms/mL 235U). The smallest measurable isotope shift of approximately 3 pm was determined for the 409.01 nm ion spectral line. Detection limits (DL) were obtained under optimized ICP operating conditions to be in the range of 70-150 ng/mL, except for the 238U component of the 286.57 nm line (300 ng/mL). This latter result was determined to be due to a strong, previously unreported, absorption interference from the argon plasma. The 235U isotope component (DL 70 ng/mL) was found to be unaffected. This work demonstrates the applicability of ICP-CRDS for uranium isotopic measurements. The potential of development of a field-deployable, on-line uranium isotope monitor using plasma-CRDS is discussed.

Solid-phase extraction-spectrophotometric determination of uranium(VI) in natural waters

A method for the extraction and determination of uranyl ion in natural waters using octadecyl bonded silica membrane disks modified with piroxicam and spectrophotometry with arsenazo(III) is proposed. The perconcentration step was studied with regard to experimental parameters such as amount of extractant, type and amount of eluent, pH, flow rates and tolerance limit of diverse ions on the recovery of uranyl ion. The limit of detection of the proposed method is 0.4 micro g L(-1) of uranyl. The method was applied to the recovery of uranyl from different water samples.