Search Results (17)

Tritium (³H) is a low-energy β emitter commonly found in environmental water samples, and its routine monitoring requires highly sensitive techniques capable of achieving low detection limits. Liquid scintillation counting (LSC) is the standard method for low-level ³H analysis; however, quenching significantly affects detection efficiency and minimum detectable activity (MDA), and systematic evaluations across different quench levels and measurement approaches remain limited. This study evaluates quench-related uncertainties in low-level ³H measurement using two ultra-low background liquid scintillation counters, Quantulus 1220 and GCT 6220. High- and low-quench conditions were created by varying sample-to-cocktail ratios, and performance was assessed through detection efficiency, minimum detectable activity (MDA), and stability. Under the relative measurement method with limited quench variation, GCT 6220 achieved higher efficiency, lower background, and lower detection limits. Under the internal standard method with broader quench spans, Quantulus 1220 produced smoother efficiency–quench curves and more stable results. Thus, GCT 6220 is advantageous for sensitivity-demanding scenarios, while Quantulus 1220 is better suited for quench-correction applications. Full article

Background/Objectives: Riboswitches are functional nucleic acids that regulate biological processes by interacting with small molecules, such as metabolites, influencing gene expression. Artificial functional nucleic acids, including deoxyribozymes, have been developed through in vitro selection for various catalytic functions. In a previous study, an l-histidine-dependent deoxyribozyme was identified, exhibiting RNA cleavage activity in the presence of l-histidine resembling ribonuclease catalytic mechanisms. This study aims to clarify the role of l-histidine in the activity and structural formation of the l-histidine-dependent deoxyribozyme (HD), focusing on the binding properties and conformational changes of its derivative HD3. Methods: Conformational changes in HD3 were analyzed using circular dichroism (CD) under varying concentrations of l-histidine. Direct binding analysis was conducted using carbon-14 (¹⁴C)-labeled l-histidine and a liquid scintillation counter. The catalytic activity of HD3 in the presence of different l-histidine concentrations was measured. Results: The binding constant for l-histidine-induced conformational changes (K_a(CD)) was found to be 2.0 × 10³ (M⁻¹), whereas for catalytic activity (K_a(Rxn)) and scintillation counting (K_a(RI)), it was approximately 1.0 × 10³ (M⁻¹). Conclusions: l-Histidine plays an essential role in both the catalytic activity and structural formation of the HD3 deoxyribozyme. The consistent binding constants across different experimental methods highlight the significant contribution of l-histidine to the active folding of deoxyribozymes. Full article

Ciguatera, a global issue, lacks adequate capacity for ciguatoxin analysis in most affected countries. The Caribbean region, known for its endemic ciguatera and being home to a majority of the global small island developing states, particularly needs established methods for ciguatoxin detection in seafood and the environment. The radioligand receptor binding assay (r-RBA) is among the in vitro bioassays currently used for ciguatoxin analysis; however, similarly to the other chemical-based or bioassays that have been developed, it faces challenges due to limited standards and interlaboratory comparisons. This work presents a single laboratory validation of an r-RBA developed in a Cuban laboratory while characterizing the performance of the liquid scintillation counter instrument as a key external parameter. The results obtained show the assay is precise, accurate and robust, confirming its potential as a routine screening method for the detection and quantification of ciguatoxins. The new method will aid in identifying high-risk ciguatoxic fish in Cuba and the Caribbean region, supporting monitoring and scientific management of ciguatera and the development of early warning systems to enhance food safety and food security, and promote fair trade fisheries. Full article

Tritium levels in the groundwater of arid regions are very low; in most cases, these low tritium levels cannot be detected using a conventional liquid scintillation counter (LSC). To measure the tritium activity concentration, low-level tritium in groundwater needs to be enriched by a known factor so that the scintillation counter can detect it. An electrolysis process with electrolytic cells was designed and fabricated in our laboratory following the International Atomic Energy Agency (IAEA) instructions. Nine spiked samples with a known quantity of tritium were enriched, and the tritium activity concentration was measured using the scintillation counter. The enriched water exhibits a comparable level of spiked samples, albeit with some degree of uncertainty. A correlation was drawn among the tritium activity, enrichment factor, and the required time for the electrolysis procedure. This study confirmed that an enrichment process of approximately ten- to fortyfold of the initial concentration of the tritium could be achieved using the electrolysis process with the fabricated electrolytic cells. The simple design and fabrication of the electrolysis process by controlling various parameters make it affordable to measure low-level tritium using a conventional LSC. Various statistical analyses confirmed the accuracy and precision of the data obtained by the electrolysis process. This enrichment technique would prove valuable in regions where tritium levels in groundwater are extremely low, making them challenging to detect using conventional liquid scintillation counter. Full article

Natural tritium is widely dispersed in the environment, leading to human exposure to tritium through water ingestion, inhalation of tritium gas, and absorption through the skin. High levels of tritium in the environment can pose significant health risks due to the potential carcinogenic effects of tritium. Therefore, this study aims to estimate the tritium concentration in spiked water, rainwater, and groundwater by a liquid scintillation counter (LSC). Due to the lower detection levels of the LSC, an enrichment process of tritium ten- to thirtyfold was carried out using the electrolysis process. The enriched water was then analyzed to estimate the tritium concentration. Five reference samples were prepared by diluting a standard with known concentrations (spiked sample) to verify the precision of the measurement technique. The estimated tritium levels of the rainwater and the groundwater were within the 0.3 to 3.5 tritium units (TU) range. A comparatively higher tritium concentration was estimated for the shallow wells in the lower valley of the monitored areas. However, relatively lower concentrations were detected for wells located in the hillside areas. These findings will assist regulatory authorities in formulating strategies to ensure public safety by mitigating human exposure to tritium. Full article

In arid regions, the tritium concentration in groundwater is typically very low and often falls below the minimum detectable activity (MDA) of the conventional liquid scintillation counter (LSC). Therefore, to measure the tritium activity concentration, it is necessary to lower the detection limit so that the scintillation counter can detect it. In the present study, several methods are discussed which are effective at lowering the detectable activity of tritium. One of these methods is to enrich the tritium activity concentration by ten- to fortyfold of the initial concentration of the tritium. Twelve spiked samples with known amounts of tritium, five with high concentrations and seven with low concentrations, were enriched by the electrolysis process. The results indicated that enriching the tritium levels in groundwater lowers the MDA value. Other methods are minimizing background radiation using low-background materials for sample containers, increasing the measurement efficiency of the scintillation counter and counting time, and shielding the sample from environmental radiation using the shutter option in LSC. Moreover, reducing the number of interfering contaminants in the sample can lower the uncertainty in measuring the tritium concentration in the water sample, which is beneficial for detecting low-level tritium in water to ensure public health and safety. Full article

The IsoDAR neutrino source comprises a novel compact cyclotron capable of delivering 10 mA of 60 MeV protons in cw mode and a high-power neutrino production target. It has obtained preliminary approval to run at the new underground facility Yemilab in South Korea. IsoDAR will produce a very pure, isotropic ${\overline{\nu }}_e$ source, with a peak neutrino energy of around 6 MeV and an endpoint around 15 MeV. Paired with a kton-scale detector like the planned Liquid Scintillator Counter (LSC) at Yemilab, IsoDAR can measure ${\overline{\nu }}_e$ disappearance through the inverse beta decay (IBD) channel. We expect about $1.67·{10}^6$ IBD events and 7000 ${\overline{\nu }}_e$ – e${}^{-}$ elastic scatter events in the LSC in five years of running, letting us distinguish many different models for noble (aka sterile) neutrinos and significantly improving existing limits for Non-Standard Interactions (NSIs). Finally, IsoDAR@Yemilab is sensitive to new particles produced in the target (such as light X bosons that decay to ${\overline{\nu }}_e$${\nu }_e$). We describe the accelerator developments for IsoDAR that enable us to produce about a mole of neutrinos in five years of running. These include direct injection through a radiofrequency quadrupole, exploiting complex beam dynamics, and applying machine learning in accelerator design and optimization. Full article

With the current state of water scarcity in Mafikeng, South Africa, due to low water levels and an increasing population, it is therefore crucial to ensure the sustainability and availability of the existing water resources. In this study, the levels of tritium and radiocarbon in groundwater (boreholes) at selected villages in Mafikeng were determined using the Perkin Elmer Ultra Low Liquid Scintillation Counter 2000. The mean activity concentrations of tritium are 3.61304 ± 0.00612 Bq/L and 3.86014 ± 0.00739 Bq/L for samples from Dibate and Lokaleng villages, respectively, whereas 1.83392 ± 0.02265 Bq/L is for Moletsamongwe, Lekung, Airport View and Seweding. Moreover, the mean activity concentrations of radiocarbon from Dibate and Lokaleng are 0.59296 ± 0.00886 Bq/L and 0.8333 ± 0.0126 Bq/L, respectively, whereas for, Moletsamongwe, Lekung, Airport View and Seweding, they are 1.3752713 ± 0.01968 Bq/L. Two (2) out of the forty (40) samples analysed for radiocarbon are below the minimum detectable activity of 0.33627 Bq/L. The average annual effective dose (AED) of tritium for analysed samples from Dibate and Lokaleng villages are 0.04754 μSv/y and 0.05079 μSv/y, respectively, whereas it is 0.02413 μSv/y for Moletsamongwe, Lekung, Airport View and Seweding. The average AED for radiocarbon is 0.251404 μSv/y and 0.36604 μSv/y for samples from Dibate and Lokaleng, respectively, whereas it is 0.58309 μSv/y for Moletsamongwe, Lekung, Airport View and Seweding village. The evaluated lifetime cancer risk for mortality and morbidity in adults is lower than the radiological cancer risk limit of 1.63 × 10⁻³ set by regulatory agencies; hence, the consumption of the studied groundwater from the selected villages will not pose any health risks in terms of tritium and radiocarbon levels. Full article

Radon is one of the most natural forms of radiation for human exposure. However, high-accuracy measurement of natural radon in water samples is very challenging due to the background correction, data acquisition, and sampling time. Liquid scintillation counter (LSC) and semiconductor alpha spectroscopy detectors are the most commonly used methods of determining radon concentration in water. The present study utilizes both methods to estimate radon in groundwater collected from various locations in the northeast region of Saudi Arabia. The estimated radon concentrations using Hidex 300SL are compared with a Durridge RAD7 detector to evaluate each apparatus’s abilities, advantages, and disadvantages. Both methods show radon concentrations between 0.1 and 3.20 Bq/L with an average of 0.96 Bq/L, with a standard deviation of 0.82 Bq/L. The estimated values are found to be in the safe limit recommended by the USEPA and EAEC and are far below the safe level recommended by UNSCEAR and the WHO. Comparing the estimated radon concentration using the two methods shows that although the two devices have many advantages and disadvantages based on the two different techniques, the experimental results are almost the same with experimental error. Full article

In this article, the authors report experimental results obtained for the assessment of the ²²⁶Ra content in 80 drinking water samples from the Calabria region, Southern Italy. The activity concentration, measured with the Perkin Elmer Tricarb 4910 TR Liquid Scintillation Counter (LSC) setup, was compared with the reference values reported in the Italian Legislative Decree 28/2016 in order to evaluate any possible radiological health hazards for the population in terms of ²²⁶Ra content due to the ingestion of the investigated drinking water. The obtained results put in evidence that the average ²²⁶Ra specific activity is lower than the LSC minimum detectable activity (MDA) in all cases, thus, excluding any radiological risk. They also represent the main reference for the investigated area and can be used as a baseline to extend this investigation to the whole region. Full article

²²²Rn and ²²⁶Ra concentrations of less than a few to several thousands of Bq L⁻¹ have been observed in several underground bodies of water around the world. Although regulations for these concentrations in water have been implemented internationally, there are currently no regulations in place in Japan. However, concentrations that exceed these internationally recognized regulatory values have also been observed in Japan. In this study, concentrations in spring water in the northern part of Japan were measured and the effective dose from intake of the water was evaluated. ²²²Rn concentrations were measured using a liquid scintillation counter, and ²²⁶Ra concentrations were measured using a high purity germanium detector after chemical preparation. The measured ²²²Rn concentrations (=12.7 ± 6.1 Bq L⁻¹) and ²²⁶Ra concentrations (<0.019–0.022 Bq L⁻¹) did not exceed the reference values set by international and European/American organizations. A conservative estimate of the annual effective ingestion dose of 8 μSv for ²²²Rn and ²²⁶Ra obtained in this study is much smaller than the estimated overall annual effective dose of 2.2 mSv from natural radiation to the Japanese population. However, this dosage accounts for 8% of the WHO individual dosing criteria of 0.1 mSv/year for drinking water. Full article

The physical–chemical properties of water are closely linked to the geological nature of the site where they are located. This aspect becomes even more interesting when analyzing the natural radionuclides in the drinking water of a volcanic territory such as Campania in southern Italy. This study concerned the measurement of activity concentration of gross alpha and beta, radon, and tritium to evaluate their biological impact. The measurements were carried out using alpha spectrometry for alpha emitters, proportional counter for beta emitters, the electret system for radon in water, and finally liquid scintillation for the measurement of tritium concentration. The biological impact was assessed considering the indicative dose, if applicable, and the effective annual dose of radon. Although the results show that the values are below international and national references, the radiological characterization of drinking water is of fundamental importance to optimize the radiation protection of the population. Full article

Reliable determination of ²²⁶Ra content in drinking water, surface water and groundwater is required for radiological health-risk assessment of populations and radiation-dose calculations after ingestion and inhalation. This study aimed to determine ²²⁶Ra presence in the untreated water samples on a liquid scintillation counter via Cherenkov radiation detection. Cherenkov counting is a faster, simpler, less expensive technique than other commonly used methods for ²²⁶Ra determination. Step-by-step optimization of this technique on the Quantulus detector is presented in this paper. Improvement of detection limit/efficiency in the presence of sodium salicylate was investigated in this study. The main parameters of the method obtained were detection efficiency 15.87 (24)% and detection limit 0.415 Bq/L achieved for 1000 min of counting in 20 mL of sample volume. When 1 g of sodium salicylate was added, efficiency increased to 38.1 (5)%, with a reduction in the detection limit to 0.248 Bq/L for 500 min of counting. A satisfactory precision level of Cherenkov counting was obtained, the results deviating between 5% and 20% from reference values. The precision and accuracy of the Cherenkov counting technique were compared to liquid scintillation counting (EPA Method 913.0 for radon determination) and gamma spectrometry (the direct method for the untreated water samples on HPGe spectrometer). An overview of the advantages/disadvantages of each technique is elaborated in this paper. Full article

In this paper, experiences of the last 20 years with the PERALS-technique are described. PERALS stands for photo electron-rejecting alpha liquid scintillation. This liquid scintillation technique was developed by Jack McDowell in the 1970s and is a powerful technique for the analyses of many natural alpha nuclides and also the beta nuclide ⁹⁰Sr. The principle is based on a selective extraction of the radionuclide from the water phase by means of a complexing or ion pair reagent. The extractant contains also a cocktail suitable for scintillation counting. Therefore, the extract can be analyzed directly after the extraction step. After removing quenchers, such as oxygen, and the proper setting of a pulse shape discriminator, alpha pulses can be counted with a photomultiplier. This paper describes the development of robust analysis schemes for the determination of traces of polonium, thorium, uranium and other actinides in water samples (groundwater, rain water, river water, drinking water, mineral water, sea water). For radon and radium, the enrichment in the extract is poor. Therefore, PERALS methods are not suitable for trace analyses of these analytes. In addition, the extraction of the beta-emitter ⁹⁰Sr with a PERALS cocktail is discussed, even though its beta spectrum is not analyzed with a PERALS counter. Results from the survey of drinking water and mineral water in Switzerland are presented for every radio element. Full article

In this study, to get a better understanding in characterizing groundwater and ensure its effective management, the radon concentrations in water samples were measured through Ryukyu limestone in southern Okinawa Island, Japan. Water samples were collected from a limestone cave (Gyokusendo cave, dropping water) and two springs (Ukinju and Komesu, spring water), and the radon concentrations were measured by liquid scintillation counters. The radon concentrations in the samples from the Gyokusendo cave, and Ukinju and Komesu springs were 10 ± 1.3 Bq L⁻¹, 3.2 ± 1.0 Bq L⁻¹, and 3.1 ± 1.1 Bq L⁻¹, respectively. The radon concentrations showed a gradually increasing trend from summer to autumn and decreased during winter. The variation of radon concentrations in the dripping water sample from the Gyokusendo cave showed a lagged response to precipitation changes by approximately 2–3 months. The estimated radon concentrations in the dripping water sample were calculated with the measured radon concentrations from the dripping water obtained during the study period. Based on our results, groundwater in the Gyokusendo cave system was estimated to percolate through the Ryukyu limestone in 7–10 days, and the residence time of groundwater in the soil above Gyokusendo cave was estimated to be approximately 50–80 days. This work makes a valuable contribution to the understanding of groundwater processes in limestone aquifers, which is essential for ensuring groundwater sustainability. Full article