title: Design and performance of a mass spectrometric facility for measuring helium isotopes in natural waters and for low-level tritium determination by the 3He ingrowth method.
abstract: The design and performance of a mass spectrometric system for the measurement of helium isotopes and very low tritium concentrations in natural waters are described and discussed in the light of analytical precision and accuracy. The system consists of a VG 3000 mass spectrometer with a fully automated inlet system for preparation and purification of the samples. Along with this mass spectrometric system, different custom-fabricated units are described, especially designed for taking samples, extracting helium or degassing tritium samples prior to the mass spectrometric analysis. The 3He detection limit of the system is close to 10(-16) cm3 STP corresponding to a tritium level of 0.003 TU for a 500 g water sample stored six months for 3He regrowth. A vertical oceanic tritium profile from the south hemisphere is presented as an illustration of the system's capability to detect very low tritium concentrations in the environment.
authors.affiliation: C.E.A., DSM, Laboratoire de Géochimie Isotopique, Centre d'Etudes de Saclay, Gif sur Yvette, France.
authors.forename: P
authors.initials: P
authors.lastname: Jean-Baptiste
authors.forename: F
authors.initials: F
authors.lastname: Mantisi
authors.forename: A
authors.initials: A
authors.lastname: Dapoigny
authors.forename: M
authors.initials: M
authors.lastname: Stievenard
mesh_terms: D004867:Equipment Design; D006371:Helium / Q000032:analysis; D007554:Isotopes; D013058:Mass Spectrometry / Q000295:instrumentation*; D014316:Tritium / Q000032:analysis*; D014878:Water Pollution, Radioactive / Q000032:analysis*
chemical_list: D007554:Isotopes; D014316:Tritium; D006371:Helium