A simple method for the preparation of homogeneous and stable solid powder standards: Application to sulfide analysis by LA-ICP-MS

Highlights: • A stable and mechanically resistant target was obtained by mixing the powder sample with epoxy resin. • A potential homogeneous sulfide standard, RPSS, containing 47 different elements was developed. • Homogeneity of most elements in the RPSS met the requirements for microanalysis of bulk elemental composition. • A new method for preparation of homogeneous and stable sulfide powder standards for microanalysis was proposed. A simple method for immobilizing powder samples was proposed to prepare calibration standards for the analyses of bulk elemental compositions of solid samples by LA-ICP-MS. Upon mixing with epoxy resin, the multielement doped powder was transformed into a stable and mechanically resistant target. Using this method, a sulfide standard, RPSS (resin preserved silver sulfide), was developed that contains 47 different elements, including PGE, chalcophile elements, siderophile elements, lithophile elements, and REE. The homogeneity of most elements in the original sulfide powder pressed pellet and RPSS was better than 10% (RSD, one sigma) at a microscale of larger than 24 μm. The mass fractions of most elements in the RPSS determined by LA-ICP-MS analyses, calibrated against the pressed pellet, agreed well with that of solution ICP-MS analyses. This result indicates no significant matrix effect between the RPSS target and the original powder pellet. The proposed method is convenient for quickly preparing homogenous and stable solid powder standards for LA-ICP-MS analysis. It is particularly suitable for the development of sulfide standards because it prevents them from oxidation when exposed to air; thus, the target can be preserved for long periods of time.