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Radiocarbon laboratory Isotopic techniques have become an important source to obtain additional knowledge for water source management, climate reconstruction and others environmental indicators. Our laboratory for low level radioactivity measurement developed numerous environmental studies from underground water (using the long time experience on deuterium, oxygen-18, and hydrogen measurements by mass spectrometry) to environmental tritium level around nuclear facilities. Tritium and 14C are the main radioisotopes measured in our laboratories using liquid scintillation method. Ultra low level liquid scintillation spectrometer Quantulus 1220 by its excellent performances allows environmental tritium measurement without tritium electrolytic enrichment. Tritium activity concentration measurement is performed in a short period of time and at low cost. Good laboratory practice is confirmed by obtained results in intercomparison exercises organized by IAEA Vienna (TRIC 2000 and TRIC 2004). Carbon dating using the "direct absorption" method follows similar principles to that using the benzene synthesis method. A known amount of carbon from sample standard or background material is counted as a liquid in a liquid scintillation counter. The only difference between the two methods is the way in which carbon from the sample, standard or background is converted into liquid form before being measured in the scintillation counter. Both methods convert the raw material to CO2. The benzene synthesis method then converts the CO2 to benzene (C6H6) with several intermediate steps (production of LiC and C2H2). In the direct absorption method, the CO2 is bubbled through a liquid containing a tertiary amine forming a liquid known as a carbamate. This is usually mixed with a scintillation cocktail. With the direct absorption method, it is important to know how much carbon is present in each vial containing carbon from samples, standards and backgrounds. Different laboratories have different ways of estimating the amount of carbon present in the sample. In our laboratory it is used the bubbling CO2 line to ensure that the C/P solution is always saturated for samples, standards and background. Contact person:    Carmen Varlam                                                                                                              [Print]