A universal method of sample preparation for liquid, solid, and gaseous samples based on a conversion solid-electrolyte reactor for measuring the isotope composition of light elements

Abstract

A universal conversion solid-electrolyte reactor (SER) based on zirconium dioxide stabilized by yttrium oxide is developed. It ensures the complete oxidation of organic compounds of complex molecular structure in different physical states or the complete reduction of water and organic oxygen-containing substances in a flow of helium carrier gas. The optimum oxidation operation mode of the solid-electrolyte reactor is the mode ensuring the complete oxidation of organic compounds at the boundary line of the oxidation of organic compounds and, at the same time, prevents the inflow of oxygen from the environment to the carrier gas. The potential of the working electrode selected for carrying out experiments was equal to–175 mV (oxidation operation mode). The temperature of the reactor was 940–950oC. The standard deviations δ13СVPDB for organic substances oxidized by SER varied from 0.11 to 0.57‰ and were smaller than standard deviations in the oxidation of corresponding compounds in a commercial reactor. In using the SER–IRMS method (isotope ratio mass spectrometry combined with the solid-electrolyte reactor), a minimum amount of water (60–100 ng) was required. Standard deviations δDVSMOW attained using SER and using a commercial pyrolytic reactor were close to each other. Because of the simplicity and reliability of the design, the developed SER can successfully replace commercial oxidation and reduction reactors in isotope ratio mass spectrometry. In addition, the solid-electrolyte reactor can serve as a chromatographic detector, requiring no calibration in contrast to other detectors.