Liquid Scintillation Analysis Research Articles

Measurement of β-nuclides in various solutions using plastic scintillation microspheres

BackgroundScintillation cocktails cannot directly measure samples with extreme acidity or alkalinity in β-nuclide liquid scintillation analysis. Plastic scintillation microspheres (PSm), as a novel scintillation material, offer the potential to overcome these limitations by allowing direct mixing with a variety of solutions for measurement, particularly in challenging chemical environments. ResultsThis study evaluated the performance of PSm in various chemical environments, including four acids (nitric, hydrochloric, sulfuric, and phosphoric acids), an alkaline solution (NaOH), a high-salinity solution, and methanol. PSm formed stable mixtures with most solutions and exhibited excellent chemical stability in high-concentration NaOH, with minimal chemiluminescence interference. However, concentrated nitric and sulfuric acids caused chemical reactions with PSm, leading to discoloration and potential color quenching. Efficiency calibration was performed using ultrapure water, allowing for accurate measurement of 14C activity across different solutions with simple efficiency corrections. SignificanceThe findings of this study highlight the advantages of PSm for β-nuclide measurement in a variety of complex chemical environments. PSm's stability in highly acidic, alkaline, and saline conditions makes it a promising tool for applications such as radioactive waste monitoring and pharmacokinetic research, providing a reliable and efficient alternative to conventional scintillation cocktails.

Radiological characterization for the disposal of a decommissioned LHC external beam dump at CERN

During the last Long Shutdown, a scheduled maintenance period between physics runs, the two Large Hadron Collider (LHC) beam dumps were replaced with upgraded spares modules. It was then decided to conduct an in-house autopsy and a post-irradiation examination of the removed dumps to extract information essential for the 3rd LHC physics run and to aid the design of new generations of beam dumps able to cope with future upgrades of the LHC. The need for a postmortem analysis of the dump cores opened the opportunity to combine the autopsy with processes required for the disposal of the dumps as radioactive waste at a dedicated disposal facility in France. This had a direct impact in terms of overall optimization of the interventions (postmortem analysis and prepackaging) to be performed on the dump as well as in terms of minimizing of the radiological risk (ALARA), by reducing the exposure of the personnel by combining two interventions in one. The characterization of the dump as radioactive waste was performed by means of state-of-the-art Monte Carlo and analytical techniques verified experimentally via a series of dedicated radiochemical (using liquid scintillation) analyses, conducted in-house and in external specialized laboratories. Based on these results, the dumps will be disposed of as intermediate–medium-level (FMA-VC) waste at the ANDRA CSA repository in France.

Liquid scintillation counting at the limit of detection in biogeosciences.

Liquid scintillation is widely used to quantify the activity of radioisotopes. We present an overview of the technique and its application to biogeosciences, particularly for turnover rate measurements. Microbial communities and their metabolism are notoriously difficult to analyze in low energy environments as biomass is exceedingly sparse and turnover rates low. Highly sensitive methods, such as liquid scintillation counting, are required to investigate low metabolic rates and conclusively differentiate them from the background noise of the respective analyzer. We conducted a series of experiments to explore the effects of luminescence, measurement time and temperature on scintillation measurements. Luminescence, the spontaneous emission of photons, disproportionally affects samples within the first few hours after sample preparation and can be minimized by following simple guidelines. Short measurement times will negatively affect liquid scintillation analysis or if background noise makes up a significant proportion of the detected events. Measurement temperature affected liquid scintillation analysis only when the temperature during the measurement reached approximately 30°C or higher, i.e. the liquid scintillation analyzer was placed in an environment without temperature control, but not in cases where chemicals were stored at elevated temperatures prior to measurement. Basic understanding on the functionality of a liquid scintillation analyzer and simple precautions prior to the measurement can significantly lower the minimum detection limit and therefore allow for determination of low turnover rates previously lost in the background noise.

Development of a rapid method for extraction of uranium from uranium bearing materials using ionic liquid as extracting agent from basic media

The paper presents the development of a rapid method for the direct determination of uranium using liquid scintillation analysis in uranium bearing materials with different uranium concentrations and with different impurity levels (U-ore, Uranium ore concentrate (UOC) and U-metal). Uranium extraction was carried out using hydrophobic ionic liquid Aliquat-336 thiosalicylate, ([A-336][TS]) from diluted samples in basic medium followed by liquid scintillation counting (LSC). Extraction efficiencies for uranium from aqueous medium was studied with very small volumes of ionic liquid under varying volume, pH and uranium concentration of the aqueous medium. Maximum extraction efficiency was achieved near pH 8–11. Uranium was successfully re-extracted from organic medium with nitric acid and electroplated onto stainless steel planchette for alpha spectrometry determination. Maximum re-extraction efficiency with 1 M HNO3 combined with electroplating efficiency observed was 80%. The methodology was applied for real samples. The uranium extraction efficiency using ionic liquid was about 85% for U-metal and UOC samples with comparatively low impurity level; whereas extraction efficiency for U-ore samples was found to be less than 40%. The technique can be applied for nuclear forensic applications as well as nuclear emergency scenarios for a quick initial assessment and isotopic analysis of uranium in the samples.

A liquid scintillation analysis method for low-level radioactive wastewater

There is currently general concern over low-level radioactive wastewater from the development of nuclear industry. In this paper, a method based on an ultralow-level liquid scintillation spectrometer for measuring uranium radioactivity in low-level radioactive wastewater is proposed. This method can easily and quickly measure the radioactivity level of uranium in samples and can even distinguish the main isotopes of uranium. The liquid scintillation method directly provides results in units of radioactivity activity concentration, which are more convenient for comparison with relevant national standards to determine whether the emission standards are met. The lowest limit of detection of this method is 0.014 Bq l−1 within 600 min.

A rapid method to determine 226Ra concentrations in Marcellus Shale produced waters using liquid scintillation counting

Concentrations of naturally occurring radioactive material (NORM) in Marcellus Shale produced water presents a challenge for effective management and treatment, because of the vast fluid volumes generated. With an increased emphasis on beneficial reuse and resource recovery from the produced waters, a rapid, yet reliable, method for quantifying radium in these produced waters is needed. The high total dissolved solids (TDS) concentration introduces difficulties when measuring 226Ra by recommended EPA methods that were specifically developed several decades ago for drinking water. While other techniques for measuring radium in these high-TDS fluids have since been developed, these newer techniques often require extensive and complicated pre-concentration steps; and they thus require extensive analytical chemistry skills, utilize hazardous chemicals like hydrofluoric acid, demand long holding times or measurement times, and require high sample volumes. We present a rapid method for 226Ra measurements in high-TDS produced waters by liquid scintillation counting, which has been corroborated herein by concurrent gamma spectrometry analyses. Samples were prepared for analysis by evaporating the fluid and re-suspending the evaporate with acidified distilled deionized water prior to liquid scintillation counting for 1 h. This protocol yielded radium recoveries ≥93%. Per this protocol, the alpha and beta spectra of 226Ra and its daughters were computationally separated by alpha-beta discrimination and spectrum deconvolution. The minimum detectable activities of 226Ra was 0.33 Bq/L (9.0 pCi/L) when the counting time was 60 min and the sample volume was 4 mL. Nine produced waters of varying TDS and radium concentrations from the Marcellus Shale Formation were analyzed by this method and compared with gamma spectroscopy; and these yielded comparable results with an R2 of 0.92. The reduced sample preparation steps, low cost, and rapid analysis position this as a well-suited protocol for field-appraisal and screening, when compared to comprehensive radiochemical analysis. We offer that for a given produced water region, routine and local liquid scintillation analyses can be compared and calibrated with infrequent gamma spec analyses, so as to yield a near-real time protocol for monitoring 226Ra levels during hydrofracturing operations. We present this as a pragmatic and efficient protocol for monitoring 226Ra when produced water samples host low levels of 228Ra—since the progeny of 228Ra can significantly confound the LSC analyses.

Effects of beta-endorphin and dynorphin A on in vitro apoptosis in human peripheral blood lymphocytes

Along with functioning in the nerve system, the endogenous opioid peptides as the ligands of mu-, delta-, and kappa-opioid receptors exert multiple effects on immune cells. Moreover, experimental evidence showed that morphine as an exogenous agonist of mu-opioid receptors affects immune cell viability. Such effects were discovered in experiments with cultured cells and laboratory animals. Hence, we studied effects of endogenous opioid peptides dynorphin A and beta-endorphin on viability of human peripheral blood mononuclear cells in vitro. For this, we used samples of peripheral blood cells collected from the fourteen healthy volunteers, who provided with signed informed consent and might request any information regarding the research. Mononuclear cells were collected from the heparinized blood samples according to standard protocol and cultivated in the humid atmosphere for 72 hours. Two μCi 3H-Methyl-thymidine was added into each test tube at 18 hours before the end of the cultivation period. Scintillation counting was performed by using Guardian liquid scintillation analyzer (Wallac, Finland) expressing the data as count per minute. To assess apoptosis, the cells were cultured for 24 hours in similar conditions except for adding radioactive probe. Next, the cells were stained with Annexin V-FITC/7-AAD kit (Beckman Coulter, USA) according to the manufacturer’s instructions for further recording apoptotic cells in flow cytometers BD FACSCalibur (Becton Dickinson, USA) or CytoFLEX S (Beckman Coulter, USA). The lymphocyte gate set by light scatter parameters was shown in typical Annexin V-FITC vs 7-AAD plot followed by counting Annexin V+/7-AADcells. All data were expressed as means ± S.E. Statistical significance was assessed by using Student’s t-test. It was found that physiologic concentrations of mu- and kappa-opioid receptor agonists beta-endorphin and dynorphin A exerted multidirectional effects on proliferation of human peripheral blood lymphocytes. In particular, dynorphin A increased basal proliferation and proliferation in response to suboptimal mitogen stimulation. Moreover, beta-endorphin enhanced effects of mitogen stimulation at suboptimal concentration but profoundly suppressed proliferation in maximally activated cells. The modulating effects of beta-endorphin and dynorphin A on in vitro proliferation are not associated with augmented cell apoptosis.

Radon Measurements in Bottled Waters in Greece

Underground waters pass through various types of rocks, which may contain radium and uranium isotopes in such concentrations and chemical forms that could be diluted in the water body. Thus it is possible to contain significant quantities of these radioisotopes such as radium (226Ra), which decays producing a series of alpha and beta emitters that remain in the water. Among them, radon (222Rn) and isotopes of polonium (214Po and 218Po) contribute to significant doses. In this work, we measured radium/radon concentration levels in bottled waters commercially available in Greece. Samples were concentrated by a factor of 20-100, in order to obtain more accurate results, because in the majority of the samples the concentrations measured initially were very low. To measure the radioactivity concentrations, 10 mL of concentrated sample were added to 10 mL of scintillation cocktail in a 20 mL plastic vial and then were counted with a liquid scintillation analyzer. The results show that radium/radon concentrations of the bottled waters range from 7-70 mBq/L.

Estimation of 14C in irradiated graphite using CO2 gasification method

Present paper reports development of a simple procedure for estimation of 14C in irradiated graphite samples. The process utilizes decomposition of the graphite samples by heating followed by absorption of the generated carbon dioxide in ethanolamine and analysis using liquid scintillation analyzer. The interference due to tritium was removed by acid scrubbing. The optimized method has successfully been used for analysis of a large number of actual graphite samples irradiated in research reactor. The method can specifically be used for estimation of low active specimen and even in presence of fission products and activation products.

Sequential analysis methodology for 210Po and uranium analysis by extractive liquid scintillation spectrometry

A methodology for separation and purification of 210Po from uranium, thorium and daughters has been studied. Solvent extraction coupled with liquid scintillation analysis using HDEHP (di-(2-ethylhexyl) phosphoric acid) and TOPO (trioctylphosphine oxide) in toluene as extractive scintillator was optimized. About 95% of 210Po was extracted in the organic phase of TOPO as an extracting agent from an aqueous solution in 1 M HCl, compared to 1.6% extraction by HDEHP. The methodology was validated with uranium ore tailing sample, IAEA-385 sediment and IAEA-447 Moss-soil reference materials for application to environmental samples. A minimum detectable activity of 118 mBq kg−1 was achieved.

Persistence of malathion used in dengue control on household surfaces

ABSTRACT: Dengue is a viral infection transmitted by the mosquito Aedes aegypti. In Brazil, one of the insecticides used to control the mosquito is malathion, which can be diluted in vegetable oil (1:2 v/v). The purpose of this study was to understand the persistence of malathion on different surfaces and soil. Surfaces were contaminated by malathion and then washed with water and soap. The water used to clean the surfaces was extracted and analyzed by gas chromatography with an FID detector. Soil samples received malathion 14C-TG diluted in vegetable oil (1:2 v/v) and were analyzed zero, 3, 7, 18, 32, 60, 120, 240, and 360 days after the application in a liquid scintillation analyzer. Results showed a high persistence of malathion on porous surfaces. Moreover, it did not degrade in the soil for the first 120 days.

Manipulation of mass transport rates using bead-in-a-tube method

In ultralow Pu analyses, the gold standard is thermal ionization mass spectrometry (TIMS), which requires pure sources to achieve its performance. This purity is achieved through step-wise purifications. In this work single, anion-exchange beads were trapped in the tubing to allow for dynamic solution cycling over the surface of the beads to improve the rates of metal complex uptake. Rates of Pu sorption on single ∼900 μm SIR-1200 and ∼620 μm Reillex-HPQ beads were determined for single beads trapped in a tube with syringe pump driven dynamic solution cycling over the bead, improving sorption and desorption rates. A static control was used as a comparison. Using 238Pu to enable facile activity-based measurements, rates were determined by measuring the residual Pu after contact with beads using liquid scintillation analysis (LSA) for fixed periods of time. Syringe pump driven dynamic solution cycling results in ∼5 and ∼15-fold improvements in the sorption rates for SIR-1200 and Reillex-HPQ. Impacts on desorption were also examined.

Nuclear and analytical methods for investigation of high quality wines

Nuclear and analytical methods can help to determine the year of production – vintage and the geographical provenance of high quality wines. A complex analytical investigation of Melnik fine wines from “Artarkata” vineyards, Vinogradi village near Melnik in Southwest Bulgaria using different methods and equipment were performed. Nuclear methods, based on measured gamma-ray activity of 137Cs and specific activity of 3H can be used to determine the year of wine production. The specific activity of 137Cs was measured in wines from different vintages using Low-Background High-Resolution Gamma-Spectrometry. Tritium measurements in wine samples were carried out by using a low level liquid scintillation counting in a Packard Tri-Carb 2770 TR/SL liquid scintillation analyzer. The identification of the origin of wines using their chemical fingerprints is of great interest for wine consumers and producers. Determination of 16 chemical elements in samples from soil, wine stems, wine leaves and fine wine from the type Shiroka Melnishka, which are grown in typical Melnik vineyard was made, using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES).

A new method for D2O to H2O leak detection and identification of leaky heat exchanger in PHWR by Cerenkov photon counting technique

In pressurized heavy water reactors, leaks from D2O primary coolant and moderator to H2O secondary coolant and other light-water systems in heat exchangers cannot be completely ruled out. High cost of D2O demands that its loss should be prevented to maximum extent possible. Traditionally D2O leak detection and identification of leaky heat exchanger is carried out by measurement of tritium activity in H2O. Since tritium emits low energy beta radiation, its concentration in H2O is measured by mixing it with liquid scintillation solution in a definite proportion in counting vial and counted in a Liquid Scintillation Analyzer. It is very sensitive method for leak detection, but identification of leaky heat exchanger is time consuming and may require low power operation or reactor shut down. In the new method, high energy beta emitting fission products, which emit Cherenkov photons in H2O, were used as the tracer. H2O was poured in 20 mL plastic vials without scintillator and counted on Liquid Scintillation Analyzer. D2O leak was identified by comparing the Cherenkov photon count rate with that of the blank. A discrimination ratio significantly higher than average Cherenkov photon count rate for all heat exchangers was used to identify the leaky one. The technique has advantageous over existing method of D2O leak detection, such as, (1) scintillation chemicals are not required (2) low power operation or reactor shut down is not required for identifying the leaky heat exchanger (3) no generation of radioactive chemical waste (4) on-power leak identification reduces generation of radioactive liquid waste.

Magnetic iron oxide nanoparticles for the collection and direct measurement of adsorbed alpha-emitting radionuclides from environmental waters by liquid scintillation analysis.

Radioactive contamination, be it from accidental or intentional release, can create an urgent need to assess water and food supplies and the environment, and monitor human health. In the event of such an emergency, rapid and efficient methods may be needed to assess contamination levels in scores of samples within a short time frame. Internalized exposure to radionuclides that decay by alpha (α) emission can be especially hazardous, given the strongly ionizing nature of the α particle. Unfortunately, the determination of α-emitting radionuclides using traditional radioanalytical methods is typically labor and resource intensive and time consuming. In an effort to devise methods that are fast, require little labor and laboratory expendables, and minimize the use of toxic or corrosive reagents, researchers at PNNL have evaluated superparamagnetic nanoparticles as extracting agents for α-emitting radionuclides from chemically unmodified and acidified (pH 2) aqueous systems. It is demonstrated that bare magnetite nanoparticles exhibit strong affinity for two representative α-emitting radionuclides (241Am and 210Po) from two representative aqueous matrices (river and ground water). Furthermore, use of the superparamagnetic properties of these nanomaterials to concentrate the analyte-bearing solids from the bulk aqueous solution has been demonstrated. The nanoparticle concentrate can be either directly dispensed into a scintillation cocktail, or first dissolved and then added to a scintillation cocktail as a solution for an α-emission assay by liquid scintillation analysis. Despite the severe quenching caused by the metal oxide suspensions in the cocktail, the authors have demonstrated that modern liquid scintillation analyzers can report accurate α activity count rates; the upper limits of nanoparticle suspension concentrations in a cocktail are reported for cases wherein normal instrument count mode and a quench correction protocol are used. Discussions are provided on the presented sample processing and analysis method, the improvement (lowering) of minimum detectable activity concentrations using the nanoparticle-based assay method, and the quenching effects of nanoparticle suspensions in a scintillation cocktail.

Aclonifen Uygulama Zamanının Tilki kuyruğu [Alopecurus myosuroides Huds. (Poaceae)] Yapraklarındaki Kritik Konsantrasyon Değerine Etkisi

The objective of this study was to determine the effect of different treatments times of aclonifen, which is used as pre- and post-emergence herbicide in the control of blackgrass [Alopecurus myosuroides Huds. (Poaceae)] on the critical concentration values resulting in 100% success. The plants of A. myosuroides were grown on pots under greenhouse conditions. In the study, to determine the herbicide contraction on the plant tissues accurately, 14C-aclonifen was added to the aclonifen suspension concentrate (SC) Challenge 600 and suggested dose (270 g e.m. da-1) was treated. The trials were initiated in march and april of 2011 and the treatments were applied the first (pre-emergence), 20th (early post-emergence) and 40th (later post-emergence) days. 10-day after each treatment, the symptoms were evaluated; and, the fresh and dry weights of the leaves were recovered. The aclonifen concentration on the fresh and dry leave samples were determined by the measuring the total radioactivity amount in dpm using liquid scintillation analyzer. The results of the trials indicated that the suggested doses of aclonifen critical concentration on the A. myosuroides leaves were: 1.58 ± 0.16 nmol/mg dry weight for pre-emergence; 3.04 ± 1.57 and 0.94 ± 0.81 nmol/mg dry weight for early and late post-emergence, respectively. It was also determined that the treatment of aclonifen with suggested dose when applied either as pre-emerge or as early post emergence until the plants reach 1-2 leaf stage before emergence or until 1-2 leaf stage result in 100% control; however, the treatments applied after 3-4 leaf stage are not successful although they result in delays of plant development.

Determination of ultratrace-levels of 99Tc in low-level radioactive waste samples using ICP-QMS

This paper proposes a rapid, accurate method of measuring 99Tc in low-level radioactive waste using microwave digestion, TEVA resin for chemical separation, and inductively coupled plasma-quadrupole mass spectrometry (ICP-QMS). The minimum detectable activity of ICP-QMS for the determination of 99Tc was 8.5 mBq g−1 (13.6 pg g−1). The proposed method achieved chemical recovery of 88 % and with sensitivity superior to that of alternative radiochemical methods (e.g., liquid scintillation analyzer or LSA) when the data acquisition time for identical, low-concentration samples was taken into account.

Excretion of [3H]triptolide and its metabolites in rats after oral administration

To investigate the routes of elimination and excretion for triptolide recovered in rats. After a single oral administration of [(3)H]triptolide (0.8 mg/kg, 100 μCi/kg) in Sprague Dawley rats, urine and fecal samples were collected for 168 h. To study biliary excretion, bile samples were collected for 24 h through bile duct cannulation. Radioactivity was measured using a liquid scintillation analyzer, and excretion pathway analysis was performed using an HPLC/on-line radioactivity detector. The total radioactivity recovered from the urine and feces of rats without bile duct ligation ranged from 86.6%-89.1%. Most of the radioactivity (68.6%-72.0%) was recovered in the feces within 72 h after oral administration, while the radioactivity recovered in the urine and bile was 17.1%-18.0% and 39.0%-39.4%, respectively. The HPLC/on-line radiochromatographic analysis revealed that most of the drug-related radioactivity was in the form of metabolites. In addition, significant gender differences in the quantity of these metabolites were found: monohydroxytriptolide sulfates were the major metabolites detected in the urine, feces, and bile of female rats, while only traces of these metabolites were found in male rats. Radiolabeled triptolide is mainly secreted in bile and eliminated in feces. The absorbed radioactivity is primarily eliminated in the form of metabolites, and significant gender differences are observed in the quantity of recovered metabolites, which are likely caused by the gender-specific expression of sulfotransferases.

Interaction of Platelets with Poly(vinylidene fluoride-co-hexafluoropropylene) Electrospun Surfaces

Platelets are the major contributors in the process of thrombosis and in the failure of biomedical implants. A number of factors influence the platelet interaction with foreign surfaces such as surface morphology, surface chemistry, and adsorbed proteins. This study examined the effect of surface topography and chemistry of pristine and fibrinogen-adsorbed solvent cast (SC) and electrospun (ES) samples of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) on platelet adhesion, activation, and aggregation. Qualitative and quantitative studies of fibrinogen adsorption were performed using time-of-flight secondary ion mass spectrometry (ToF-SIMS), while SEM, aggregometry, and liquid scintillation analyses were performed to evaluate platelet adhesion, aggregation, and serotonin release. While little or no platelet adhesion was observed on pristine ES surfaces, considerable adhesion, and measurable aggregation and serotonin release were observed on pristine SC surfaces. Notably, increased adhesion of platelets was observed following fibrinogen adsorption on SC surface with considerable aggregation and serotonin release compared with ES samples, where limited aggregation and platelet adhesion was observed. A further comparison of platelet adhesion, aggregation, and serotonin release was performed with plasma-adsorbed SC and ES surfaces. SC surfaces showed enhanced platelet adhesion, aggregation, and serotonin release compared to ES surfaces. This study shows that the morphology of samples plays a critical role on the biocompatibility of samples by altering the adsorption and adhesion of biomolecules and cells. The low level of adhesion, low aggregation, and serotonin release of platelets, even in the presence of fibrinogen and plasma-derived proteins, suggested that ES samples have the least thrombogenicity.

Identification and Quantification of Radionuclides in Contaminated Drinking Waters and Pipeline Deposits

There is broad international interest, particularly with Homeland Security and first-responder organizations, in developing a range of effective, robust, and rapid analytical tools to identify terrorist assaults. Accidental or intentional radionuclide contamination of drinking water supplies would have significant public health, social, political, and financial implications even where the real risk might be small given public perception. Rapid identification and assessment of the magnitude of any contamination is critical in managing any threat and ultimately in allaying public and regulator concerns and in steering subsequent remediation operations. Conventional screening techniques do not provide information of the radionuclide present, and subsequent identification techniques are too time-consuming and require some prior knowledge of the nuclide identity to permit accurate quantification. The development described here presents a novel, rapid, and effective radiometric approach using industry-standard liquid scintillation counting equipment that can both identify and quantify alpha and beta radionuclide contamination within 1 h of sample receipt. The liquid scintillation counting (LSC) or liquid scintillation analysis (LSA) method, though widely used by the life science and the (14)C scientific communities since the 1960s, has greater potential than is often used. The technique developed here, which uses multiple quench parameters for nuclide identification, has been tested on both contaminated drinking waters and pipeline scales with compositions typical of those that might be encountered. It is shown to be highly effective both in terms of rapidly identifying the radionuclide and providing a measure of the quantity of radionuclide present. The whole procedure is about to be developed into an integrated analytical system for use by untrained personnel. It is notable that the development could also be readily applied as a QC procedure in routine radioanalytical measurements.