Automated radioanalytical system incorporating microwave-assisted sample preparation, chemical separation, and online radiometric detection for the monitoring of total 99Tc in nuclear waste processing streams

An automated fluidic instrument is described that rapidly determines the total (99)Tc content of aged nuclear waste samples, where the matrix is chemically and radiologically complex and the existing speciation of the (99)Tc is variable. The monitor links microwave-assisted sample preparation with an automated anion exchange column separation and detection using a flow-through solid scintillator detector. The sample preparation steps acidify the sample, decompose organics, and convert all Tc species to the pertechnetate anion. The column-based anion exchange procedure separates the pertechnetate from the complex sample matrix, so that radiometric detection can provide accurate measurement of (99)Tc. We developed a preprogrammed spike addition procedure to automatically determine matrix-matched calibration. The overall measurement efficiency that is determined simultaneously provides a self-diagnostic parameter for the radiochemical separation and overall instrument function. Continuous, automated operation was demonstrated over the course of 54 h, which resulted in the analysis of 215 samples plus 54 hly spike-addition samples, with consistent overall measurement efficiency for the operation of the monitor. A sample can be processed and measured automatically in just 12.5 min with a detection limit of 23.5 Bq/mL of (99)Tc in low activity waste (0.495 mL sample volume), with better than 10% RSD precision at concentrations above the quantification limit. This rapid automated analysis method was developed to support nuclear waste processing operations planned for the Hanford nuclear site.     

Microwave-assisted sample treatment in a fully automated flow-based instrument: oxidation of reduced technetium species in the analysis of total technetium-99 in caustic aged nuclear waste samples

An automated flow-based instrument for microwave-assisted treatment of liquid samples has been developed and characterized. The instrument utilizes a flow-through reaction vessel design that facilitates the addition of multiple reagents during sample treatment and removal of the gaseous reaction products and enables quantitative removal of liquids from the reaction vessel for carryover-free operations. Matrix modification and speciation control chemistries that are required for the radiochemical determination of total (99)Tc in caustic aged nuclear waste samples have been investigated. A rapid and quantitative oxidation procedure using peroxydisulfate in acidic solution was developed to convert reduced technetium species to pertechnetate in samples with high content of reducing organics. The effectiveness of the automated sample treatment procedures has been validated in the radiochemical analysis of total (99)Tc in caustic aged nuclear waste matrixes from the Hanford site.     

Determination of (234)th in marine samples by liquid scintillation spectrometry

A liquid scintillation spectrometry method for the determination of (234)Th in seawater with (230)Th as the yield tracer has been developed and validated. (234)Th is separated from the dissolved phase by an Fe(OH)(3) precipitation and is then purified using ion exchange chromatography. The counting source is prepared by taking the sample to dryness in a vial, redissolving in acid, and mixing with a scintillation cocktail. The instrument employed has a relatively low background (11 cpm) and the ability to separate α from β activity on the basis of pulse shapes. The (234)Th + (234m)Pa counting efficiency is 50% over the counting window employed. The limit of detection, using the above parameters, a 20 L sample, and a 400 min count is found to be 0.04 dpm L(-)(1). It was also demonstrated that less advanced instruments, without α/β separation, can also be used effectively.     

Development and performance of the diffusive gradients in thin-films technique for the measurement of technetium-99 in seawater

A novel technique for obtaining time-integrated 99Tc concentrations in seawater has been developed, using diffusive gradients in thin films (DGT). The performance of TEVA resin as a binding agent for 99Tc was investigated via laboratory experiments. The accumulated 99Tc activity per unit area of resin-gel was proportional to both the bulk solution activity and the exposure time for deployments of up to 2 weeks. The response of DGT was found to be independent of solution chemistries over the pH range 3-8 and ionic strength range 0.01-1.3 M. Seawater has pH 8 and ionic strength of approximately 0.7 M; therefore, the potential of the technique for field deployment in seawater was demonstrated. Detection limits of 0.05 and 0.025 Bq L(-1), for 2- and 4-week DGT deployments, respectively, were calculated for 99Tc measurement by liquid scintillation spectrometry. Using quadrupole ICPMS to measure bound 99Tc could reduce these detection limits to 0.125 mBq L(-1) for a 4-week deployment. These detection limits are sufficiently low for monitoring contaminated environments, including the Irish Sea. This method is simpler and faster than other 99Tc analysis methods and represents the only means of obtaining time-integrated data.     

Radionuclide sensors based on chemically selective scintillating microspheres: renewable column sensor for analysis of (99)tc in water

A method for chemically selective radiometric sensing of non-γ-emitting radionuclides in solution is described. Using scintillating microspheres with selective radionuclide uptake properties, radiochemical separation and radiometric detection steps are integrated within a sensor device. These microspheres are loaded into a renewable minicolumn that serves to capture, preconcentrate, and separate radionuclides. The preconcentrating minicolumn also localizes and retains radionuclides within a detector of well-defined geometry and emits a photometric signal. The sensor material in the column can either be regenerated with eluent chemistries or be renewed by fluidic replacement of the beads. The latter method allows the use of materials that bind analytes irreversibly or are unstable under regeneration conditions. Radionuclide-selective scintillating microspheres were prepared by coimmobilization of scintillating fluors and selective organic extractants within the pores of an inert polymeric support. Preparation and characterization of microspheres, and their use for selective quantitative sensing of (99)Tc(VII), is described in detail. A sensor-based procedure for (99)Tc(VII) analysis was developed and successfully applied toward the determination of (99)Tc(VII) in groundwater samples from the Hanford site, using standard addition techniques for quantification. Using a 50-mL sample volume and signal accumulation time of 30 min, the detection limit for (99)Tc(VII) was 0.37 dpm/mL (9.8 pg/mL).     

Direct On-Line Coupling of Capillary HPLC with (1)H NMR Spectroscopy for the Structural Determination of Retinyl Acetate Dimers: 2D NMR Spectroscopy in the Nanoliter Scale

This paper presents the application of directly coupled capillary high-performance liquid chromatography (capillary HPLC) and proton high-field nuclear magnetic resonance spectroscopy (NMR) for structural elucidation of a so-far unknown kitol isomer. One- and two-dimensional continuous- and stopped-flow NMR spectra were recorded in a 180 μm i.d. capillary, corresponding to a detection volume of only 200 nL. Unequivocal structural assignment on the basis of 1D and 2D stopped-flow capillary HPLC-NMR experiments was performed. The kitol isomer mixture was present in a sample of thermally isomerized retinyl acetate and separated on a capillary column.     

Stability of technetium and decontamination from ruthenium and molybdenum in determination of 99Tc in environmental solid samples by ICPMS

A rapid and efficient method for the determination of (99)Tc in environmental solid samples was developed using chromatographic separation combined with inductively coupled plasma mass spectrometry (ICPMS) measurement. The volatility of technetium during sample ashing and solution evaporation was investigated to establish a reliable sample pretreatment procedure. A novel approach was developed to improve the removal of molybdenum and ruthenium in chromatographic separation using 30% H(2)O(2) pretreatment of the loading solution and extraction chromatographic separation using two serial small TEVA columns. The decontamination factors of more than 4 × 10(4) and 1 × 10(5) are achieved for molybdenum and ruthenium, respectively. Chemical yields of technetium in entire procedure range from 60% to 95% depending on the type and amount of samples, and the detection limit of 0.15 mBq/g for (99)Tc was obtained. The method has been successfully applied for the determination of (99)Tc in environmental solid samples.     

High-resolution determination of 147Pm in urine using dynamic ion-exchange chromatography.

A procedure has been developed for measuring 147Pm in bioassay samples, based on the separation and preconcentration of 147Pm from the urine matrix by adsorption onto a conventional cation-exchange column with final separation and purification by HPLC using dynamic ion-exchange chromatography. The concentration of 147Pm is determined by collecting the appropriate HPLC fraction and measuring the 147Pm by liquid scintillation counting. The limit of detection is 0.1 Bq (3 fg) 147Pm based on a 500-mL sample of urine and a counting time of 30 min with a background of 100 cpm. Ten samples can be processed in 1.5-2 days.     

Prospects for development of a process for recovering technetium from spent fuel of nuclear power plants

Comperative analysis is made of the Tc behavior in different stages of spent fuel reprocessing, to make a decision on the process allowing separation of Tc as an individual product. The electrochemical and sorption processes for separating Tc from nitric acid solutions are tested. The electrochemical process presents significant difficulties, and it appears more favorable to recover Tc as an individual product in the first extraction cycle. Based on the fractionation principle, a scheme can be suggested in which Tc is separated along with Np in the first cycle and then recovered using ion exchange or extraction.     

Determination of 36Cl in nuclear waste from reactor decommissioning

An analytical method for the determination of 36Cl in nuclear waste such as graphite, heavy concrete, steel, aluminum, and lead was developed. Several methods were investigated for decomposing the samples. AgCl precipitation was used to separate 36Cl from the matrix elements, followed by ion-exchange chromatography to remove interfering radionuclides. The purified 36Cl was then measured by liquid scintillation counting. The chemical yield of chlorine, as measured by ICPMS, is above 70% and the decontamination factors for all interfering radionuclides are greater than 10(6). The detection limit of this analytical method for 36Cl is 14 mBq. The method has been used to determine 36Cl in heavy concrete, aluminum, and graphite from the Danish DR-2 research reactor.     

Decontamination of uranium-contaminated waste oil using supercritical fluid and nitric acid

The waste oil used in nuclear fuel processing is contaminated with uranium because of its contact with materials or environments containing uranium. Under current law, waste oil that has been contaminated with uranium is very difficult to dispose of at a radioactive waste disposal site. To dispose of the uranium-contaminated waste oil, the uranium was separated from the contaminated waste oil. Supercritical R-22 is an excellent solvent for extracting clean oil from uranium-contaminated waste oil. The critical temperature of R-22 is 96.15 °C and the critical pressure is 49.9 bar. In this study, a process to remove uranium from the uranium-contaminated waste oil using supercritical R-22 was developed. The waste oil has a small amount of additives containing N, S or P, such as amines, dithiocarbamates and dialkyldithiophosphates. It seems that these organic additives form uranium-combined compounds. For this reason, dissolution of uranium from the uranium-combined compounds using nitric acid was needed. The efficiency of the removal of uranium from the uranium-contaminated waste oil using supercritical R-22 extraction and nitric acid treatment was determined.     

Determination of selenium in human blood by high-performance liquid chromatography with fluorescence detection

Selenium was determined in human whole blood or red cells by high-performance liquid chromatography (HPLC) using a new internal standard. The method provides a 0.15-ng detection limit, a between-day standard deviation of 1% at the 20-ng level, and a 3% within-day standard deviation at the 1-ng level. Samples were wet-ashed, and a selenium-diaminonaphthalene derivative was formed, followed by addition of tetraphenylnaphthacene internal standard, reverse-phase HPLC separation (10 min/run), and fluorescence detection. The detection limit was reduced by discrimination of fluorescence excitation of the selenium complex from the background using long-wavelength excitation (480 nm), removal of stray light in the excitation beam, and other optimizations described. Representative aliquots of frozen and thawed whole blood samples were obtained by using a nitric acid predigestion at ambient temperature. Procedures to validate the method included standard addition and neutron activation analysis.     

Comparison and improvement of the determinations of actinide low activities using several alpha liquid scintillation spectrometers

We applied three procedures using two a liquid scintillation spectrometers (PERALS and TRI-CARB) and two scintillation cocktails (Alphaex and Ultima Gold LLT) for the determination of alpha-emitter low activities. For each procedure, the limit of detection, the resolution, the separation factor, and the Fischer coefficient were determined in order to perform 232U-234U-238U isotopic measurements. The deconvolution usually performed is clean when the PERALS spectrometer is used. This is not possible for the TRI-CARB spectrometer using the Ultima Gold LLT scintillation cocktail. This problem was solved by combining the advantages of both techniques using the Alphaex scintillation cocktail in the TRI-CARB spectrometer. Under these conditions, the limit of detection was improved, the resolution decreased from 500-800 to 420-590 keV, and the separation factor increased from 0.9 to 1.1-1.2. This third procedure was applied with success for 232U-234U-238U isotopic experiments.     

Quantitative detection of trichloroacetic acid in human urine using isotope dilution high-performance liquid chromatography-electrospray ionization tandem mass spectrometry

The chemical disinfection of drinking water to control microbial contaminants results in the formation of disinfection byproducts (DBPs). The volatile trihalomethanes and the nonvolatile haloacetic acids (HAAs) are the most prevalent DBPs. It is important to monitor human exposure to HAAs because of their potential adversehealth effects, such as cancer. Among the HAAs, urinary trichloroacetic acid (TCAA) is a potential valid biomarker for assessing chronic ingestion exposure to HAAs from drinking water. We have developed a rugged, high-throughput, sensitive, accurate, and precise assay for the measurement of trace levels of TCAA in human urine using a simple solid-phase extraction (SPE) cleanup followed by isotope dilution high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). TCAA is extracted from the urine using SPE, separated from other extract components by reversed-phase HPLC, and analyzed by negative ion electrospray ionization-isotope dilution-MS/MS using a multiple reaction monitoring experiment. The method is simple and fast and is not labor intensive (sample preparation and analysis can be performed in approximately 15 min) with a limit of detection of 0.5 ng/mL in 1 mL of urine.     

Performance assessment and uncertainty evaluation of a portable NaI-based detection system used for thyroid monitoring

This work aims at assessing the performance of a portable detection system, equipped with an NaI(Tl) scintillation detector for in vivo thyroid monitoring, which was properly calibrated using an anthropomorphic neck phantom. The anthropomorphic physical phantoms commonly used for the efficiency calibration of in vivo counters often present certain limitations regarding the geometry and the activity distribution. Therefore, the feasibility of these detection systems for in vivo monitoring should be assessed whenever possible. To accomplish this assessment, patients to whom (99m)Tc and (123)I marked radiopharmaceuticals have been administered in the framework of nuclear medicine diagnostic procedures were monitored. As the biokinetic models of the administered radiopharmaceuticals are known, the time-dependent activity functions in the critical organs after administration are easily quantified. The measured activities in the thyroid using the NaI(Tl) scintillation detector were compared with the estimated activities using the biokinetic models, in order to reach conclusion about the applicability of the portable scintillation counter for in vivo thyroid monitoring. The state-of-the-art Monte Carlo computer program PENELOPE and two voxel phantoms (male and female) were used to evaluate the overall uncertainties influencing the thyroid monitoring. A computational parametric study was performed to quantify the influence of several parameters in the activity quantification (neck-detector distance, thyroid shape, thyroid size and overlying tissue thickness), which allowed one to gain insight and to better understand the discrepancies between the calculated and measured activities.     

Evaluation of flow cell detector configurations combining simultaneous preconcentration and scintillation detection for monitoring of pertechnetate in aqueous media

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.     

超高效液相色谱-串联质谱法测定水产品中三聚氰胺残留量

本文建立超高效液相色谱-串联质谱(UPLC-MS/MS)快速测定水产品中三聚氰胺残留的方法。色谱条件:ACQUITY UPLC BEH HILIC柱(2.1×100 mm,1.7m),流动相:乙腈-0.5 mmol/L乙酸铵溶液(0.1%甲酸),流速:0.3mL/min。采用电喷雾质谱检测,以正离子模式5min就完成了质谱分析。实验结果表明,三聚氰胺在水产品中的检测限为0.05 mg/kg,在0.05~0.50 mg/kg添加水平时加标回收率为63%~90%之间,相对标准偏差(RSD,n=6)均小于7.2%。     

Determination of 99Tc in aqueous solutions of various cationic compositions using a varian 725-ES inductively coupled plasma optical emission spectrometer

A procedure was developed for determining the gravimetric concentration of ⁹⁹Tc in aqueous solutions from spent nuclear fuel reprocessing without their preliminary separation, using an inductively coupled plasma optical emission spectrometer (ICP-OES). The optimal conditions for minimizing spectral and matrix interferences were determined. They allowed the lower limit of Tc determination in process salt solutions to be decreased from 1 to 0.25 mg l^?1.     

Sorption preconcentration of radionuclides on Taunit carbon nanostructural material

The possibility of using Taunit carbon nanostructural material for sorption recovery of radionuclides from aqueous solutions was examined. Taunit efficiently recovers Am, Pu, Eu, U, and Tc from weakly acidic and neutral solutions. Taunit is a suitable support for preparing solid extractants based on a phosphonium ionic liquid and diphenyl(dibutylcarbamoylmethyl)phosphine oxide for recovery of actinides from nitric acid solutions.     

Rapid Determination of Technetium-99 in Large Volume Seawater Samples Using Sequential Injection Extraction Chromatographic Separation and ICP-MS Measurement

An automated method was developed for rapid determination of (99)Tc in large volume seawater samples. The analytical procedure involves preconcentration of technetium with coprecipitation, online separation using extraction chromatography (two TEVA columns) implemented in a sequential injection setup, and measurement of (99)Tc by inductively coupled plasma mass spectrometry (ICP-MS). Chromatographic behaviors of technetium, molybdenum, and ruthenium were investigated, and the mechanism of adsorption and elution of TcO(4)(-) on a TEVA column using HNO(3) was explored. The results show that not only NO(3)(-) but also acidity (or concentration of H(+)) of the loading or eluting solution affect the adsorption and desorption of TcO(4)(-) on TEVA resin. Decontamination factors of more than 1 × 10(6) for ruthenium and 5 × 10(5) for molybdenum are achieved. Chemical yields of technetium in the overall procedure range from 60% to 75% depending on the sample volumes, and a detection limit of 7.5 mBq/m(3) (or 11.5 pg/m(3)) for 200 L of seawater was obtained. Compared with the conventional analytical procedure, the developed method significantly reduces analytical time. A batch of samples (n > 4) can be analyzed within 24 h. The method has been successfully applied for rapid and automated determination of low level (99)Tc in large volume seawater samples. The analytical results of seawater samples collected in Denmark show a good agreement with the values obtained using the conventional method.