Micro-determinations of C, N, S, H, He, metallic Fe, δ¹³C, δ¹⁵N and δ³⁴S in geologic samples

抄録

Pyrolysis-combustion, direct combustion and hydrolysis procedures have been developed for study of returned lunar samples. These procedures are also applicable to the analysis of numerous elements on relatively small geological specimens. During pyrolysis-combustion, the sample is degassed at 150°C, heated in vacuum to 1, 225°C and the various gaseous products are measured and collected. Then, the pyrolysis residue is combusted in a partial atmosphere of oxygen and additional gaseous products are collected. The above method allows the following measurements: C (as CO₂, CH₄ and CO); total H, total He, total N, combusted C, δ¹³C_PDB and δ¹⁵N_air. By direct combustion in oxygen, the abundances of C, S, N and He, as well as δ¹³C_PDB, δ¹⁵N_air and δ³⁴S_CD are determined. Hydrolysis involves reacting the sample in 6N H₂SO₄ overnight at 105°C. The gaseous products collected and measured are: S (as H₂S), δ³⁴S_CD, acid hydrolyzable CH₄, He and % metallic Fe (from H₂ released). Standards were analyzed to demonstrate the capabilities and reliabilities of the different experiments. A suite of lunar samples was studied using these new techniques. Replicate and duplicate analyses of these samples and a comparison with literature values obtained by different methods show a high degree of confidence which can be placed in the techniques described.