The Istituto di Geoscienze e Georisorse (IGG), on behalf and with the support of the International Atomic Energy Agency (IAEA), prepared eight geological materials (three natural waters and five rocks and minerals), intended for a blind interlaboratory comparison of measurements of boron isotopic composition and concentration. The materials were distributed to twenty seven laboratories ‐ virtually all those performing geochemical boron isotope analyses in the world ‐which agreed to participate in the intercomparison exercise. Only fifteen laboratories, however, ultimately submitted the isotopic and/or concentration results they obtained on the intercomparison materials. The results demonstrate that interlaboratory reproducibility is not well reflected by the precision values reported by the individual laboratories and this observation holds true for both boron concentration and isotopic composition. The reasons for the discrepancies include fractionations due to the chemical matrix of materials, relative shift of the zero position on the δ11B scale and a lack of well characterized materials for calibrating absolute boron content measurements. The intercomparison materials are now available at the IAEA (solid materials) and IGG (waters) for future distribution.

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Thorium and iodine memory effects have been characterized experimentally for inductively-coupled plasma mass spectrometry by adding ammonia gas directly to the spray chamber and nebulizing aqueous ammonia sample solutions to assess analyte memory retention sites. Thorium memory effect originates from the tendency of an unidentified thorium compound to volatilize from the spray-chamber walls, and not from Th compound adsorption to nebulizer tubing. The mass spectrometer skimmer and sampler cones, ion optics, quadrupole, and other components are not responsible for the memory effect. Unlike that of thorium the iodine memory effect originates from adsorption of iodine compounds on nebulizer tubing surfaces and from volatilization of HI and I2 from the spray-chamber walls. Addition of ammonia sample solutions or ammonia gas directly to the spray chamber eliminated the Th and I memory effects in practical analyses, and blank levels were achieved after 2 min wash-outs. Quantitative recoveries were obtained for Th and I in reference materials.