In order to determine organically bound tritium (OBT) concentrations, environmental samples are generally first freeze-dried. This first step is to remove tritiated water. Then, the dry residue is burnt in a special furnace with oxygen. Finally, the tritiated water fraction obtained is measured using a liquid scintillation counter. Our laboratory has developed a "pyroxydiser" tubular furnace for a computer controlled combustion. This paper presents the different improvements of the equipment. For three years, the analysis of each sample has been replicated. The experience acquired on the environmental matrices analysed using this setup is shown.