Isotopic determination of silver in picomole quantities by surface ionization mass spectrometry

A microanalytical procedure is described for the quantitative of Ag from natural samples by anion exchange and by surface ionization mass spectrometry using silica as an emitter. The isotopic composition of 50 pmol of Ag be measured on a Faraday detector with a precision of 0.1%. Isotopic measurements have been made on as little 0.15 pmol with a precision of 1% using an electron multiplier . The total procedural blank for the anion exchange is 0.15 pmol. Using stable isotope dilution 0.5 pmol Ag, which Is 3 X 10^(11) atoms, can be measured with a of better than 1% with only a 30% blank correction. allows the accurate determination of Ag in natural samples to concentration levels of 1 pmol per gram. The ionization for Ag is about 1-2% and the detection limit 1 fmol. This procedure has been applied to several meteorites, and a standard terrestrial rock.