Comparison of scintillation cocktails and vials for determination of 3H activity concentration

Krajcar Bronić, Ines; Barešić, Jadranka (2019) Comparison of scintillation cocktails and vials for determination of 3H activity concentration. In: Popić, Jelena; Coha, Ivana; Krajcar Bronić, Ines; Knežević Medija, Željka, (eds.) Zbornik radova Dvanaestog simpozija Hrvatskog društva za zaštitu od zračenja. Zagreb, Hrvatsko društvo za zaštitu od zračenja, pp. 370-375 .

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Abstract

For determination of tritium (3H) activity concentration by liquid scintillation spectrometry method, various scintillation cocktails are mixed with water samples to enable counting tritium decays in liquid scintillation counter. Some scintillation cocktails contain dangerous chemicals, such as NPE (nonylphenolethoxylates) that is harmful for biota in aqueous systems. Use of NPE will be soon forbidden and scintillation cocktails should be biodegradable. At the same time, it is required that the new biodegradable scintillation cocktails retain at least the same counting properties as the best cocktails today. We performed several tests with different scintillation cocktails: Ultima Gold LLT, (UGLLT, by PerkinElmer, “Safer” coctails that contains DIPN - Diisopropyl naphthalene isomers that may be harmful for aquatic biota, suitable for measurement of 3H activity concentration in various types of water, having low background and efficiency of 30 %), Gold Star LT2 (GS, by Meridian Biotechnologies, contains NPE and is considered as a Substances of Very High Concern, harmful for biota in water systems), and ProSafe LT+ (PS, by Meridian Biotechnologies, biodegradable) from two different containers (aluminium and glass). For each test we prepared several samples having 3H activity concentration from 0 Bq/L (tritium-free water, i.e., background) to 600 Bq/L. The ratio sample:cocktail was always 8 mL:12 mL, measurements were performed by LSC Quantulus 1220 for 300 minutes (6 cycles of 50 minutes), and for evaluation of measured spectra the optimized tritium window, channelin the range 25 – 253, was used. The following parameters were compared: background count rate B, calibration factor CF, Standard Quench Parameter SQP(E), detection limit DL, figure of merit FOM and measurement efficiency E. Scintillation cocktail UltimaGold LLT showed in all test best characteristics. Scintillation cocktail GoldStar LT2 (Meridian Technologies) from the first batch showed similarly good performances, while the second batch (GS/2) showed worse performances, most probably due to some changes in the chemical composition. ProSafe LT+ (Meridian Technologies) is also a good scintillation cocktail, although having slightly higher detection limit and lower efficiency. However, this cocktail should be packed in glass bottles. An attempt to use aluminium container was not successful and PS from the aluminium container showed the worst performances among the tested scintillation cocktails. Three types of high density polyethylene vials were also tested (PerkinElmer, Zinsser Analytic and Meridian Technologies) and all showed the same performances if the same scintillation cocktail was used. Therefore, the choice of vials for routine application would depend also on their cost.

Item Type:	Conference or workshop item published in conference proceedings (UNSPECIFIED)
Uncontrolled Keywords:	3H; LSC; scintillation cocktails; vials
Subjects:	NATURAL SCIENCES > Interdisciplinary Natural Sciences NATURAL SCIENCES > Interdisciplinary Natural Sciences > Radiation Science
Divisions:	Division of Experimental Physics
Depositing User:	Ines Krajcar Bronić
Date Deposited:	23 Apr 2019 10:50
URI:	http://fulir.irb.hr/id/eprint/4499

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