We operate two dedicated mass spectrometric systems for helium isotope analysis and tritium measurement by the He-3 ingrowth method, respectively (both systems contain VG 5400 mass spectrometers as central units). The systems are fully automated and run over night. The separation of He isotope and tritium measurements on dedicated machines allows us to improve the sample turnaround time. It further ensures very low detection limits in order to carry out very low level tritium analysis. The throughput of the systems is high with appoximatelly 1500 - 2000 samples per year.
The Helium-Neon mass-spectrometer is used to analyze groundwater and ocean-water samples with typical samples sizes between 40 to 80g of water. A VG5400 mass-spectrometer performs high precision helium isotope analyzis while a quadrupole mass-spectrometer (Pfeiffer PrismaPlus) is used to analyze neon isotopes. The precision for determination of the He-3/He-4 ratio typically is ±0.2 percent. However, it can approach ±1 percent if the samples contain high He-4 concentrations or extreme He-3/He-4 ratios. Neon isotopes can be analyzed with a presicon around 0.3 to 0.5 percent.
Technically the Tritium mass-spectromter is very similar to the Helium-Neon Massspectrometer. It is used to analyse helium isotopes in order to determine the tritium content of the water sample by the He-3 ingrowth method. The mass-spectrometer is deticated to those kind of analysis only, assuring a very clean system with very low background necessary to analyze samples with very low helium concentrations. Tritium can be measured with a precision of about ±1 to 2 percent (1 sigma) and a detection limit of 0.01 TU or better. The throughput is about 60 samples per week.