Simultaneous determination of 226Ra and 228Ra in food samples using liquid scintillation counting

The 228Ra and 226Ra isotopes of radium are significant contaminants in food, raising public concern because of their radiotoxicity. Several methods are available for determining 228Ra and 226Ra. However, the application of these procedures is not focused on food but only on water and environmental matrices. In this study, a cost-effective method for the simultaneous determination of 226Ra and 228Ra radioactivity in food samples using liquid scintillation counting was developed. The overall efficiencies of 226Ra and 228Ra in the food samples are 69.4-78.4% and 30.1-35.8%, respectively. The minimum detectable activities of 226Ra and 228Ra are 11.3 mBq/g and 33.4 mBq/g, respectively, in our food sample, obtained using a 1.0 g ash sample and 60 min of counting time. The method was validated using IAEA-certified reference materials and compared with data obtained using gamma spectrometry in tea, kelp, and oyster samples.

The dynamics of the detection of 226Ra in water by scintillation counting in nonequilibrium conditions

The conventional methods for the ²²⁶Ra determination by liquid scintillation counting require to attain secular equilibrium between ²²⁶Ra and ²²²Rn prior to the counting. This study describes a method that allows the immediate counting of a sample after the dissolution of Ba(Ra)SO₄ in EDTA. This results from a detailed modelling of the activity of the parent ²²⁶Ra and its daughters in both the aqueous and organic scintillator phases. This methodology was tested on standard solutions of ²²⁶Ra showing promising results.

Environmental evaluation of radioactivity levels and associated radiation hazards in groundwater around the WIPP site

Groundwater may contain radioactive substances which can be dangerous to human health. Concentrations of natural radionuclides polonium (Po), thorium (Th), uranium (U), and radium (Ra) isotopes were measured in groundwater samples collected from different locations in the vicinity of the Waste Isolation Pilot Plant (WIPP) site in Carlsbad, New Mexico. The average values of gross activity concentrations of ²¹⁰Po, ²²⁸Th, ²³⁸U, ²³⁴U, ²²⁶Ra and ²²⁸ Ra isotopes were determined to be 1.62 Bq L^-1 in shallow groundwater and 5.88 Bq L^-1 in deep groundwater, respectively. The total radioactivity in deep groundwater was higher than that in shallow groundwater, and most of the radioactivity in the water is from ²²⁶Ra. Furthermore, the effective doses for ingestion of natural radionuclides were about 0.333 mSv y^-1 for shallow groundwater and about 1.338 mSv y^-1 for deep groundwater samples, which are higher than the World Health Organization (WHO, 2017) guideline level (0.1 mSv y^-1) for drinking water. Ra dominated the total ingestion dose, contributing 93.06 % and 75.40 % of the total effective doses to the deep and shallow groundwater, respectively. The ingrowth and decay of natural radionuclides suggested that ²²⁸Ra/²²⁶Ra ratio can be a useful indicator of the source of radioactive contamination. The radioactivity data obtained from the investigated groundwater samples can be used to establish a baseline for radioactivity levels in groundwater around the WIPP site.

226Ra and 137Cs determination by inductively coupled plasma mass spectrometry: state of the art and perspectives including sample pretreatment and separation steps

Achieving precise and accurate quantification of radium (²²⁶Ra) and cesium (¹³⁷Cs) by inductively coupled plasma mass spectrometry (ICP-MS) is of particular interest in the field of radiological monitoring and more widely in environmental and biological sciences. However, the accuracy and sensitivity of the quantification depend on the analytical strategy implemented. Eliminating interferences during the sample handling step and/or during the analysis step is critical since presence of matrix elements can lead to spectral and non-spectral interferences in ICP-MS. Consequently, before the ICP-MS analysis, multiple sample preparation approaches have been applied to purify and/or pre-concentrate environmental and biological samples containing radium and cesium through years, such as (co)-precipitation, solid phase extraction (SPE) or dispersive SPE (dSPE). Separation steps using liquid chromatography and capillary electrophoresis can also be useful in complement with the abovementioned sample preparation techniques. The most attractive sample handling technique remains SPE but efficiency of the extraction procedures is currently limited by sorbent specificity. Indeed, with the recent advances in ICP-MS instrumentation, it becomes indispensable to eliminate residual interferences and improve sensitivity. It is in this direction that it will be possible to meet analytical challenges, e.g. analyzing radium and cesium at concentrations below the pg L^-1 range in complex matrices of small volumes, as they are found for instance in pore waters or in biological samples. Development of new innovative sorbents based for example on hybrid and nanostructured materials has been reported with the aim of enhancing sorbent specificity and/or capacity. In the present review, the performances of the different analytical approaches are discussed, followed by an overview of applications.

Measurement of radium and radon in water using a combination technique of radon-emanation and pair-measurements methods

Since ²²²Rn is continuously generated by the decay of ²²⁶Ra, it is difficult to analyze ²²²Rn in water containing ²²⁶Ra. To analyze ²²⁶Ra, a large amount of water is passed through a manganese fiber column to adsorb radium, and then radium delayed coincidence counting or gamma-ray spectroscopy is performed approximately four weeks later. A combination technique of radon-emanation and pair-measurement was tested to analyze ²²⁶Ra and ²²²Rn in water. ²²⁶Ra and ²²²Rn were accurately analyzed within approximately 8 d.

Optimal methods for preparation, separation, and determination of radium isotopes in environmental and biological samples

In recent years, radium has attracted considerable attention primarily because of the rapid increase in unconventional (fracking) drilling technology in the United States and around the world. One of the major radionuclides of interest in unconventional drilling wastes is radium isotopes (²²⁴Ra, ²²⁶Ra, ²²⁸Ra). To access long-term risks associated with radium isotopes entering into the environment, accurate measurements of radium isotopes in environmental and biological samples are crucial. This article reviews many aspects of radium chemistry, which includes recent developments in radiochemical separations methods, advancements in analytical techniques followed by a more detailed discussion on the recent trends in radium determination.

Some physicochemical parameters and 226Ra concentration in groundwater samples of North Guilan, Iran

The ²²⁶Ra concentration and some physicochemical parameters have been measured in thermal spring waters used for medical therapy and drinking purposes in the Astara basin of North Guilan, Iran. The radon emanation method was performed using the AB-5 photomultiplier tube to measure the ²²⁶Ra concentration in water samples. Also, the physicochemical parameters of the water were measured in situ using a portable multimeter-VWR multi. The average concentrations of ²²⁶Ra were ranged between 3.4 ± 0.06 to 38.2 ± 0.08 mBq l^-1. For all samples, the ²²⁶Ra concentration values range is lower than the maximum admissible value recommended by the WHO report. The relation between the physicochemical parameters and ²²⁶Ra activity concentration of groundwater was assessed. The results indicate a significant correlation coefficient between ²²⁶Ra concentration and T, as well as acidity pH. Anomalously high ²²⁶Ra concentrations in groundwater are preferentially found in high temperate and electric conductivity along with the acidic environment.

Simple and sensitive determination of radium-226 in river water by single column-chromatographic separation coupled to SF-ICP-MS analysis in medium resolution mode

This article describes a novel and simple method to measure ultra-trace ²²⁶Ra in river water samples at fg L^-1 (mBq L^-1) levels as a means for surveying ²²⁶Ra in an unintended contamination in river water. To simplify the procedure, a single column was used for separation and purification; 10 mL of AG 50W-X8 resin was packed into a 10 mL Eppendorf pipette tip, which was used as a separation column. A 500 mL sample solution was loaded, and interfering elements were removed with 80 mL 4 M HCl in 20% ethanol. Subsequently, Ra together with Ba was eluted by 20 mL 5 M HNO₃ prior to SF-ICP-MS analysis; this allows the naturally existing Ba in water samples to be employed as a yield tracer for ²²⁶Ra analysis. Using the medium mode of SF-ICP-MS, the instrumental detection limit of 380 fg L^-1 (10 mBq L^-1) was obtained. An extremely low method detection limit of 0.46 fg L^-1 (0.02 mBq L^-1) was achieved with 500-fold pre-concentration. Finally, the developed technique was applied to analyze natural water samples collected from Japanese rivers, in which the ²²⁶Ra concentrations varied in the range of 0.7-49.6 fg L^-1 (0.03-1.82 mBq L^-1).