Evaluation of an extractive scintillation medium for the detection of uranium in water

Roane, J. E.; DeVol, Timothy A.

doi:10.1007/s10967-005-0011-7

Cited by 15 publications

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“…The combination of a separation chemistry and scintillation in polymeric beads was first demonstrated several years ago using ion-exchange beads; however, collection and counting were done in separate manual steps . The concept has now been exploited in a number of reports for radionuclide sensors and analyzers. ,− …”

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confidence: 99%

Equilibration-Based Preconcentrating Minicolumn Sensors for Trace Level Monitoring of Radionuclides and Metal Ions in Water without Consumable Reagents

2006

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A sensor technique is described that captures analyte species on a preconcentrating minicolumn containing a selective solid-phase sorbent. In this approach, the sample is pumped through the column until the sorbent phase is fully equilibrated with the sample concentration, and the exit concentration equals the inlet concentration. On-column detection of the captured analytes using radiometric and spectroscopic methods is demonstrated. In trace level detection applications, this sensor provides a steady-state signal that is proportional to sample analyte concentration and is reversible. The method is demonstrated for the detection of Tc-99 using anion-exchange beads mixed with scintillating beads and light detection, Sr-90 using SuperLig 620 beads mixed with scintillating beads and light detection; and hexavalent chromium detection using anion-exchange beads with spectroscopic detection. Theory has been developed to describe the signal at equilibration and to describe analyte uptake as a function of volume and concentration, using parameters and concepts from frontal chromatography. It is shown that experimental sensor behavior closely matches theoretical predictions and that effective sensors can be prepared using low plate number columns. This sensor modality has many desirable characteristics for in situ sensors for trace level contaminant long-term monitoring where the use of consumable reagents for sensor regeneration would be undesirable. Initial experiments in groundwater matrixes demonstrated the detection of Tc-99 at drinking water level standards (activity of 0.033 Bq/mL) and detection of hexavalent chromium to levels below drinking water standards of 50 ppb.

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confidence: 99%

Equilibration-Based Preconcentrating Minicolumn Sensors for Trace Level Monitoring of Radionuclides and Metal Ions in Water without Consumable Reagents

2006

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“…These resins were used to separate 14 C, 131 I, 239 Pu, and mixed fission products from various matrixes (water, urine, milk) . Recent research efforts have focused on finding new materials combining separation and scintillation detection for the use in on-line, real-time flow cells. − Successful materials realized for the detection of 99 Tc in near neutral aqueous solutions use either the Aliquat-336 extractant or anion-exchange resin as sorbents combined with different scintillating materials. The combination of scintillator and sorbent has been realized in the form of a mixed-bed resin, , or the extractant was coated onto a polystyrene or acrylic porous resin, which had been impregnated with different fluors such as 2,5-diphenyloxazole (PPO) and 1,4-bis(4-methyl-5-phenyloxazol-2-yl-)benzene (DM-POPOP), − PPO and 1,4-bis(2-methylstyryl)benzene (bis-MSB) 18 or 2-(1-naphthyl)-5-phenyloxazole (αNPO) .…”

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confidence: 99%

“…Flow cells used with extractive scintillating resins have so far consisted of small columns or pieces of plastic tubing, which contained the resin and which were placed in front of one or two photomultiplier tubes. − The sensitivity of the PMT is not uniform over the face; the region in the center has the highest sensitivity. When using a small-volume flow cell this can lead to fluctuations in detector response, which interferes with quantification.…”

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Evaluation of Flow Cell Detector Configurations Combining Simultaneous Preconcentration and Scintillation Detection for Monitoring of Pertechnetate in Aqueous Media

Hughes

DeVol

2006

Anal. Chem.

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Flow cell detectors were developed for simultaneous concentration and scintillation detection of technetium-99 in water. Evaluated flow cell geometries consisted of a coil and a fountain flow cell design; the latter is based on radial solution flow through a resin bed interfaced with a photomultiplier tube through a polycarbonate window. The sorptive scintillating media investigated were (1) an extractive scintillator combining a porous polystyrene resin with the extractant Aliquat-336 and fluor 2-(1-naphthyl)-5-phenyloxazole, (2) a mixed bed of organic scintillator (BC-400) and Tc-selective resin (TEVA), and (3) a mixed bed of inorganic scintillator particles (CaF2-Eu) with either TEVA resin or strong base anion-exchange resin (Dowex 1 x 8-400(Cl)). Depending on flow cell geometry and medium, the detection efficiencies for 99Tc ranged from 7.26 (BC-400/TEVA in coil geometry) to 50.20% (CaF2(Eu)/Dowex 1 x 8-400(Cl) in fountain flow cell geometry). The configuration with the highest sensitivity, CaF2(Eu)/Dowex 1 x 8-400(Cl) in coil geometry, can detect 99Tc as low as 3.78 Bq L(-1) for a 100-s count interval and a 200-mL sample, which is below the current regulatory level of 33 Bq L(-1). The issue of sensor reusability was addressed in this research, and its potential application at near neutral pH was demonstrated. The optimal sensor design was evaluated with a 99Tc-spiked synthetic groundwater matrix.

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“…For these experiments, 500 Bq L –1 uranium-233 in pH 6 simulated groundwater (SGW) was filtered through the UVMs. SGW was prepared according to the recipe of Smith et al with the following composition: 10.4 ppm of Ca 2+ , 217.5 ppm of Cl – , 7.8 ppm of NO 3 – , 10 ppm of K + , 744.2 ppm of HCO 3 – , 17.5 ppm of Mg 2+ , 354.7 ppm of SO 4 2– , 570.2 ppm of Na + , 20.1 ppm of F – , and 10 ppm of Si 4 + . Measurements were performed in triplicate.…”

Section: Experimental Sectionmentioning

confidence: 97%

“…For these experiments, 500 Bq L −1 uranium-233 in pH 6 simulated groundwater (SGW) was filtered through the UVMs. SGW was prepared according to the recipe of Smith et al 17 Isotope Discrimination in SGW. To analyze the ability of the alpha spectrometer to discriminate uranium isotopes mounted on the ultrafiltration membrane substrates, SGW spiked with 5.4 ppm depleted uranium was adjusted to pH 6 and filtered through 100 kDa UVMs.…”

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confidence: 99%

Rapid Sample Preparation for Alpha Spectroscopy with Ultrafiltration Membranes

et al. 2018

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This contribution describes a rapid, fieldable alpha spectroscopy sample preparation technique that minimizes consumables and decreases the nuclear forensics timeline. Functional ultrafiltration membranes are presented that selectively concentrate uranium directly from pH 6 groundwater and serve as the alpha spectroscopy substrate. Membranes were prepared by ultraviolet grafting of uranium-selective polymer chains from the membrane surface. Membranes were characterized by Fourier-transform infrared spectroscopy before and after modification to support functionalization. Membrane performance was evaluated using uranium-233 or depleted uranium in both deionized and simulated groundwater at pH 6. Functionalized membranes achieved peak energy resolutions of 31 ± 2 keV and recoveries of 81 ± 4% when prepared directly from pH 6 simulated groundwater. For simulated groundwater spiked with depleted uranium, baseline energy resolution was achieved for both isotopes (uranium-238 and uranium-234). The porous, uranium-selective substrate designs can process liters per hour of uranium-contaminated groundwater using low-pressure (<150 kPa) filtration and a 45 mm diameter membrane filter, leading to a high-throughput, one-step concentration, purification, and sample mounting process.

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Evaluation of an extractive scintillation medium for the detection of uranium in water

Cited by 15 publications

References 0 publications

Equilibration-Based Preconcentrating Minicolumn Sensors for Trace Level Monitoring of Radionuclides and Metal Ions in Water without Consumable Reagents

Equilibration-Based Preconcentrating Minicolumn Sensors for Trace Level Monitoring of Radionuclides and Metal Ions in Water without Consumable Reagents

Evaluation of Flow Cell Detector Configurations Combining Simultaneous Preconcentration and Scintillation Detection for Monitoring of Pertechnetate in Aqueous Media

Rapid Sample Preparation for Alpha Spectroscopy with Ultrafiltration Membranes

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