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Fig. 3 Typical l inearly spectrum of U nat measurement.
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Fig. 3 Typical linearly spectrum of Unat measurement. Fig. 2 Linearlyalpha/beta spectrum – mineral water Čerínska. The green colour represents beta spectrum (originates from 228Ra with maximal energy of beta particles 1.3 MeV) and blue colour represents alpha spectrum (226Ra emit alpha particles with energies 4.78 MeVand 4.60 MeV). LiquiScint 2004LSC in Radiochemistry and Environmental Sciences 17 - 18 May 2004, Prague, Czech Republic DETERMINATION OF 226Ra AND Unat IN MINERAL WATERS USING LIQUID SCINTILLATION SPECTROMETRYM. Vršková1, J. Merešová1, Z. Kassai21Water Research Institute in Bratislava1Nábr. arm. gen. L. Svobodu 5, 812 49 Bratislava, SlovakiaEmail: j.meresova@pobox.sk2Cyclotron Centre of Slovak Republic Bratislava, Slovakia Nowadays we observe the increased trend of consumption of the natural mineral waters, which in many cases start to substitute the function of the normal drinking water. Mineral waters according to increased contents of minerals (mineralization ranged from 1000 to 4000 mg.dm-3) can simultaneously contain increased concentrations of natural radionuclides. For that reason it is necessary to pay attention to monitor radioactivity of the mineral and thermal springs. In the region of Slovakia there are hundreds of springs, which are used for drinking. The most frequently attendant nuclides in water are from the uranium decay chain: the mixture of 238U and 234U, marked as Unat, 226Ra and gaseous 222Rn. We have studied radionuclides 226Ra and Unat. They were determined in mineral waters by two different methods, which are consecutively compared. Tab. 1 Derived intervention level of the isotopes of radium and uranium in drinking waters Unat is determined by spectrophotometer and LSC. Uranium is concentrated and isolated from simultaneous elements via sorption on high porosity silica gel. After elution with acetic acid is uranium determined by a) reaction with reagent arzenazo III into the coloured complex on spectrophotometer JENWAY 6300 b) solution is transposed to vial with scintillation cocktail and measured on TRICARB 2900TR The proportional detector and LSC determine concentration of 226Ra. The radium is concentrated and separated by coprecipitation with barium/lead as sulphate. Sulphate precipitation is a) added to scintillator ZnS and measured on scintillation detector NA 6201 II b) transposed to vial with scintillation cocktail andmeasured onTRICARB 2900TR Tab. 2 The comparison of concentrations of 226Ra in bottled mineral waters measured by scintillation detector and LSC. Tab. 3 The comparison of concentrations of Unat in bottled mineral waters measured by spectrophotometry and LSC. The activity concentration of 226Ra and the mass concentration of Unat were measured for 9 bottled mineral waters freely available in trade net. In the tables 2 and 3 are compared the results of measurements. The concentration of any sample exceeds the derived intervention level (tab. 1).