Dear Sir. Concerning your issue about the protocol to analyse Tritium/OBT with a LSC. This is based partly on empirical findings that tritium discharged mostly as HTO can become transformed into organic forms in environmental samples. An international workshop was convened in France in 2012 to gather the scientific community interested in organically bound tritium to share their experience and to establish a current state of knowledge. This paper summarises the outcome of the workshop, which aimed to improve skills concerning OBT (Organically Bound Tritium) determination, transfer and behaviour in the environment. In order to improve OBT measurement credibility, it was decided to conduct and promote OBT analysis through inter-laboratory exercises. There are many different methods for analysing the various forms of tritium in environmental samples; however, there are no published standard methods for measuring OBT. Furthermore, there are no certified reference materials of OBT for environmental samples. As a general feature, the measurement of the various tritium fractions requires several stages, potentially leading to the use of different analytical procedures and apparatuses to treat samples. Moreover, the distinction between exchangeable OBT (atoms bound to oxygen and nitrogen; E-OBT) and non-exchangeable OBT (atoms bound to carbon; NE-OBT) is difficult to observe due to the difference in solubility of the organic molecules forming the environmental samples. As a result, different behaviours are observed during the labile exchange stage where, in addition to the isotopic exchange between the sample and non-tritiated water, some organic molecules are solubilised. Moreover, for OBT there is no consensus on the unit to report the activity values. Indeed, results are given either in Bq.L–1 of combustion water, Bq.kg–1 of dry sample or Bq.kg–1 of fresh sample without any other information. This can make any comparison of the results somewhat problematic. When tritium fractions have to be analysed, the sampling and storage are key points, and caution is necessary to avoid any uncontrolled variation. I think the following below links may help you in your analysis:

 http://ehs.columbia.edu/TritiumAssayInLiquidsUsingLSC.pdf

http://www.radioprotection.org/articles/radiopro/pdf/2013/01/radiopro120067.pdf

http://hps.ne.uiuc.edu/rets-remp/PastWorkshops/2010/1%20Taskaev%20Liq%20Scint%20C14%20.pdf

https://www.nrc.gov/docs/ML1216/ML12167A343.pdf

Thanks

Thanks, but i was more looking to the sample preperation of OBT for LSC.

The LSC 2017 conference will be hold in 1-5 May, 2017 in Copenhagen, there is a session of tritium studies, this might be interest to your research related to tritium. please see the detailed information in the conference website: http://lsc2017.nutech.dtu.dk/

For determination of OBT in vegetation and other solid sample, the free tritium (HTO) is first removed by heating at low temperature or freez dry, the combustion can be used for separation of OBT. This is quite often used and straight forward method.

Dear Sir,

Our laboratory participated to inter-comparison exercises organized by OBT Group starting with 2013. The exercises measured Total OBT in different samples: potatoes, sediments, wheat, and now is ongoing, grass. Each exercise had dedicated meeting and during those meetings I saw communications about different techniques. If you have a Pyrolyser, you can catch combustion water in HNO3 solution of 0.1 M (RADDEC procedure). Be careful for level of OBT, because this procedure can be applied to high level of OBT. If you want to measure sample from uncontaminated environment (tritium concentration of combustion water below 10 Bq/L) you need to use a combustion bomb (we use Parr bomb), followed by neutralization and lyophilization of combustion water. LSC (Quantulus 1220) + Parr bomb + purification of combustion water can measure sample with OBT around 1 Bq/L in its combustion water. We use this procedure in our laboratory.

Thank you Carmen Varlam!

yes Pyrolyser is the answer. In India, at Environmental Survey Laboraotory Kalpakkam used pyrolyser (supplied by Noki Technology) and measured using LSS.