Rapid determination of 89,90Sr in wide range of activity concentration by combination of yttrium, strontium separation and Cherenkov counting

Novel approach for strontium preconcentration from seawater and rapid determination of 89,90Sr in emergency situations

A novel approach for rapid ^89,90Sr determination in seawater samples is developed. For the first time in the radioanalytical application, the features of the synthetic zeolite Z4A and a highly selective material for Sr separation were synergically employed. Seawater composition significantly reduces Sr yield on highly selective solid-phase extraction materials, making the preconcentration step essentially important but laborious and time-consuming. To address this issue, the ability of zeolite 4A to concentrate the Sr from the seawater matrix was employed. With the proposed method, two important goals were achieved: (i) simple preconcentration of Sr that can be conducted directly at the sampling site, enabling a rapid procedure for ^89,90Sr determination in emergencies, and (ii) high and stable Sr recoveries (89 ± 4%) necessary for lowering detection limits. Strontium is effectively separated from 1 L of seawater in less than 1.5 h, which is especially important in emergency situations, such as the Fukushima Daiichi Nuclear Power Plant accident. Minimum detectable activities achieved for ⁸⁹Sr:⁹⁰Sr activity ratio ∼10:1 were 0.74 Bq/L for ⁸⁹Sr, and 1.47 Bq/L for ⁹⁰Sr, detected by Cherenkov counting, 36-38 h after separation, and 30 min counting time.

Synergy of flow injection system and molecular recognition technology products for rapid determination of 89,90Sr and 210Pb

A rapid, automated separation procedure was developed for radioactive strontium and lead isotope determination. This system includes a portable automated system for the preconcentration and sequential elution of targeting isotopes with an Na₂H₂EDTA solution from solid phase extraction materials, AnaLig®Sr-01 and SuperLig®620, provided by IBC Technologies. Strontium and lead were separated from the majority of matrix constituents to obtain pure fractions of Pb and Sr prior to radiometric detection. In case of barium presence, it can also be fully isolated and completely separated from Sr. The automated procedure can be successfully used for preconcentration and separation from high as well as low radioactivity samples. With only a 1 mL column filled with SuperLig®620, it is possible to isolate Sr and Pb with 100% recovery from 1 L to 2 L of sample at a flow rate of up to 10 mL min^-1 within several hours. ^89,90Sr isotopes can be further determined by Cherenkov counting, while ²¹⁰Pb isotopes can be determined by either gamma spectrometry or liquid scintillation counter. The method was tested and validated using certified standard materials and proficiency test samples. The synergy of automated separation and detection procedures enables the determination of the low level activity of ⁹⁰Sr and ²¹⁰Pb in a short time with detection limits of 20 mBq L^-1 for both isotopes. The proposed method enables lower labour costs, minimal size of apparatuses and columns, low separation time, and reduced secondary waste production. The automated procedure may be easily implemented in laboratories worldwide and can also be used at sampling sites.

Evaluation of different methods for measuring 89Sr and 90Sr: Measurement uncertainty for the different methods as a function of the activity ratio

In case of a radiological emergency situation involving e.g. fission of uranium or plutonium, analysis of radioactive strontium will be of importance. The primary radionuclides of interest are ⁹⁰Sr, its progeny ⁹⁰Y and ⁸⁹Sr. A few days following an event, ⁸⁹Sr will be the predominant radioisotope of strontium. Most methods found in the literature are valid and applicable when measuring ⁹⁰Sr, but when samples contain both ⁸⁹Sr/⁹⁰Sr interference problematics arise. How these interferences are dealt with will have an effect on the uncertainty of the ⁹⁰Sr determination. This work aims at evaluating three measurement approaches, all mentioned in the literature, with respect to the measurement uncertainty when determining ⁹⁰Sr in an emergency preparedness situation and to propose a suitable measurement strategy.

Time optimization of 90Sr determinations: sequential measurement of multiple samples during decay of 90Y

This work presents an optimized method for the determination of multiple samples containing ⁹⁰Sr when its daughter ⁹⁰Y is measured after chemical separation and in sequence, i.e. during its decay. Consequently the measurement times will increase for each subsequent sample, since there has been a longer time for decay before measurement. Compared to a previously published approach, when ⁹⁰Y is measured during its ingrowth, the gain in total analysis time (time for ingrowth+ summation of measurement times) is not that large, particularly not for low background instruments. However, results for a large part of the samples can be delivered earlier.