Abstract
The effects of packing materials on H infiltration into sample capsules during piston-cylinder experiments has been examined using samples of oxalic acid dihydrate, silver oxalate, and pure carbon dioxide. Mass scans revealed that as much as several mole percent carbon monoxide, accompanied by H2O, can result from a reaction between H and carbon dioxide in experiments using all three reactants. A measurable O isotopic shift was detected in carbon dioxide samples where carbon monoxide was detected. Traditional means for measuring C-O-H volatile composition at the end of piston-cylinder experiments will not identify this chemical change in the volatile composition and may result in erroneous determination of fluid composition. Glass and witherite packing materials effectively maintained a low fH2 around the samples.
