A specialized single channel inlet system has been developed for urea breath tests and scientific studies using Isotope Ratio Mass Spectrometer Helicomass. The system consists of sampling needle, manifold with its purification system, the possibility to introduce sample and standard, high vacuum Mamyrin leak valve to inlet the sample to electron ionization ion source, and the purification procedure including series of sequential pumpings out and blowdowns with compressed nitrogen. The system inlets sample up to 4•10–6 Torr in the mass-spectrometer analytical chamber. The measuring precision was 0.1% for 21 measurements, which meets the test requirements. The measuring time was 15 min per sample including the standard measurement, system purification, the sample measurement, and the second purification. The combination of system and Helicomass mass-spectrometer fits requirements for procedure used to identify infections by Helicobacter pylori.