Trace Analysis of Elements in a Palladium Matrix

Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is a technique for trace elemental analysis and isotopic distribution determination at trace levels, but ICPMS cannot handle directly high concentrations of ions. Dimethylglyoxime will selectively precipitate palladium from acid solutions leaving most of the impurities in solution and allowing their quantitation by ICP-MS without dilution. By avoiding dilution, the sensitivity and precision of the analysis can be increased to sub-PPM levels. A convenient method for controlled etching of palladium is also described. Introduction The exact requirement(s) for the Fleischmann-Pons Effect (FPE) 1 is not clear, but it may be dominated by surface effects. Trace contaminants on the surface influence the uptake and recombination of deuterium (or hydrogen) by blocking or enhancing certain catalytic centers or causing certain crystalline phases to form during processing that may influence the FPE. A classic example in organic synthesis is Lindlar’s catalyst. Normally, palladium in the presence of hydrogen will completely hydrogenate triple and double bonds to the saturated alkanes. However, in the case of Lindar’s catalyst the palladium is poisoned with lead and further deactivated with either quinoline (an amine) or a thiol. This deactivated catalyst has a sufficiently slow hydrogenation rate to allow stopping the hydrogenation at the double-bond stage. Lindar’s catalyst allows the preparation of many cis-alkenes from acetylenes. For example, several steps in the multi-step preparation of Vitamin E are accomplished on an industrial scale with this catalyst. To fully understand the FPE requires analysis of the palladium before and after various processes to determine if either: (1) An impurity is present that inhibits or enhances some chemical or other process. The impurity may come from the surface, bulk of the palladium, or from the reagents or equipment used in the reaction; or, (2) Transmutation had occurred where a new element or isotope was formed that was not initially present in either the bulk starting palladium, solutions, or equipment used for the reaction. 1 Although the mechanisms may be completely different, I use the term Fleischmann-Pons Effect in this a paper to refer to a palladium matrix exposed to deuterium and production of excess heat, elements, or isotopes. The method of introduction of deuterium need not be only through electrolysis, as in the original Fleischmann-Pons experiments.