METHOD OF PRODUCING CALIBRATION GAS MIXTURE WITH GIVEN RATIO OF STABLE ISOTOPES OF CARBON AND OXYGEN Russian patent published in 2025 - IPC G01N1/28 

FIELD: chemistry.

SUBSTANCE: invention relates to metrological assurance of uniformity of measurements of ratios of stable isotopes. Disclosed is a method of producing a calibration gas mixture with a given ratio of stable carbon isotopes and oxygen, which consists in the fact that from the available N^th number of gas sources of carbon dioxide, two sources are selected, which differ as much as possible in isotopic composition ¹²C¹⁶O₂, ¹³C¹⁶O₂ and ¹²C¹⁸O¹⁶O, then, based on the preset ratio of stable isotopes of oxygen and carbon, the mixing ratio of the content from the two selected carbon dioxide sources is calculated, after which at temperature of 20 ± 2 °C in volume of 10 l for 4 hours, mixing four components - carbon dioxide of purity of not less than 99.95% from two selected sources in the found proportion and in a given amount, as well as oxygen and nitrogen of purity of not less than 99.999% in an amount specified in advance by calculation, wherein the volume is pre-evacuated to a residual pressure of 2 Pa, and during the entire mixing process, an external mechanical effect is exerted on it with frequency of 30 revolutions per minute, wherein forced mutual circulation of mixed components takes place.

EFFECT: invention enables to create a calibration gas mixture with a certified characteristic of delta values of the ratio of stable isotopes of carbon and oxygen, as well as a characteristic of the volume fraction of CO₂.

1 cl, 1 ex