Nikolov Jovana, Stojković Ivana, Todorović Nataša, Tenjović Branislava, Vuković Srđan, Knežević Jovana
University of Novi Sad, Faculty of Sciences, Department of Physics, Novi Sad, Serbia.
University of Novi Sad, Faculty of Technical Science, Novi Sad, Serbia.
Appl Radiat Isot. 2018 Dec;142:56-63. doi: 10.1016/j.apradiso.2018.09.013. Epub 2018 Sep 13.
Monitoring of Rn in drinking or surface waters, as well as in groundwater has been performed regularly in connection with geological, hydrogeological and hydrological surveys and health hazard studies. Liquid scintillation counting (LSC) is often preferred analytical method for Rn measurements in waters as it allows multiple-sample automatic analysis. LSC method implies mixing of water samples with organic scintillation cocktail, which triggers radon diffusion from the aqueous into an organic phase for which it has a much greater affinity, eliminating the possibility of radon emanation in that manner. The main aim of this paper is calibration of the liquid scintillation counter Qunatulus 1220™ for measuring of radon in water and evaluation of two different methods (one-phase and two-phase) in order to obtain the most suitable LSC technique for radon in water measurement. In this study four different scintillation cocktails were tested: one miscible (Ultima Gold AB) and three immiscible (High Efficiency Mineral Oil Scintillator, Opti-Fluor O and Ultima Gold F). Evaluation of presented methods was based on obtained detection efficiency and achieved Minimal Detectable Activity (MDA) values. Comparison of presented methods, accuracy and precision, as well as different scintillation cocktail's performance, was considered from results of measurements of Ra spiked water samples with known activity and environmental samples. LSC results were compared with the results of radon in water measurement obtained by alpha spectrometer RAD7. Calibration was done as a dependence of calibration factor (CF) from Pulse Shape Analysis (PSA). According to the obtained results, with proper adjustment of calibration parameters, both methods could be used for radon in water measurements. The obtained MDA values for all four scintillation cocktails are very low, less than 0.1 Bq l for measuring time of 300 min.
在地质、水文地质和水文调查以及健康危害研究中，已定期对饮用水、地表水以及地下水中的镭进行监测。液体闪烁计数法（LSC）通常是水中镭测量的首选分析方法，因为它允许进行多样品自动分析。LSC方法意味着将水样与有机闪烁鸡尾酒混合，这会引发氡从水相扩散到有机相中，因为氡对有机相具有更大的亲和力，从而消除了以这种方式产生氡的可能性。本文的主要目的是校准用于测量水中氡的液体闪烁计数器Qunatulus 1220™，并评估两种不同方法（单相和两相），以便获得最适合水中氡测量的LSC技术。在本研究中，测试了四种不同的闪烁鸡尾酒：一种可混溶的（Ultima Gold AB）和三种不可混溶的（高效矿物油闪烁体、Opti-Fluor O和Ultima Gold F）。对所提出方法的评估基于获得的探测效率和达到的最低探测活度（MDA）值。从已知活度的镭加标水样和环境样品的测量结果中考虑所提出方法的比较、准确性和精密度，以及不同闪烁鸡尾酒的性能。将LSC结果与通过α光谱仪RAD7获得的水中氡测量结果进行比较。校准是作为校准因子（CF）与脉冲形状分析（PSA）的函数关系进行的。根据获得的结果，通过适当调整校准参数，两种方法都可用于水中氡的测量。对于所有四种闪烁鸡尾酒，在300分钟的测量时间内获得的MDA值都非常低，小于0.1 Bq l。
