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The paper describes a new developed method of sample gasification using yeast oxidation of monosaccharides in plant tissue for 13C/12C isotope ratio mass spectrometric analysis. Variations in the carbon isotopic composition of the leaf surface have been shown; the δ13C value for chlorophytum varies from -37 ‰ to -32 ‰ from the tip of the leaf to its base. It has been shown first that the spectral composition of radiation affects the ratio of carbon isotopes in plant leaves: the predominance of blue component in the spectrum results in accumulation of heavy 13C isotope up to δ13C = -25 ‰.

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.

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